diff options
Diffstat (limited to 'archive/2025/summer/bsc_karidas/external/concurrentqueue/concurrentqueue.h')
| -rw-r--r-- | archive/2025/summer/bsc_karidas/external/concurrentqueue/concurrentqueue.h | 3747 |
1 files changed, 3747 insertions, 0 deletions
diff --git a/archive/2025/summer/bsc_karidas/external/concurrentqueue/concurrentqueue.h b/archive/2025/summer/bsc_karidas/external/concurrentqueue/concurrentqueue.h new file mode 100644 index 000000000..2fc775400 --- /dev/null +++ b/archive/2025/summer/bsc_karidas/external/concurrentqueue/concurrentqueue.h @@ -0,0 +1,3747 @@ +// Provides a C++11 implementation of a multi-producer, multi-consumer lock-free queue. +// An overview, including benchmark results, is provided here: +// http://moodycamel.com/blog/2014/a-fast-general-purpose-lock-free-queue-for-c++ +// The full design is also described in excruciating detail at: +// http://moodycamel.com/blog/2014/detailed-design-of-a-lock-free-queue + +// Simplified BSD license: +// Copyright (c) 2013-2020, Cameron Desrochers. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without modification, +// are permitted provided that the following conditions are met: +// +// - Redistributions of source code must retain the above copyright notice, this list of +// conditions and the following disclaimer. +// - Redistributions in binary form must reproduce the above copyright notice, this list of +// conditions and the following disclaimer in the documentation and/or other materials +// provided with the distribution. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY +// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL +// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT +// OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR +// TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, +// EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// Also dual-licensed under the Boost Software License (see LICENSE.md) + +#pragma once + +#if defined(__GNUC__) && !defined(__INTEL_COMPILER) +// Disable -Wconversion warnings (spuriously triggered when Traits::size_t and +// Traits::index_t are set to < 32 bits, causing integer promotion, causing warnings +// upon assigning any computed values) +#pragma GCC diagnostic push +#pragma GCC diagnostic ignored "-Wconversion" + +#ifdef MCDBGQ_USE_RELACY +#pragma GCC diagnostic ignored "-Wint-to-pointer-cast" +#endif +#endif + +#if defined(_MSC_VER) && (!defined(_HAS_CXX17) || !_HAS_CXX17) +// VS2019 with /W4 warns about constant conditional expressions but unless /std=c++17 or higher +// does not support `if constexpr`, so we have no choice but to simply disable the warning +#pragma warning(push) +#pragma warning(disable: 4127) // conditional expression is constant +#endif + +#if defined(__APPLE__) +#include "TargetConditionals.h" +#endif + +#ifdef MCDBGQ_USE_RELACY +#include "relacy/relacy_std.hpp" +#include "relacy_shims.h" +// We only use malloc/free anyway, and the delete macro messes up `= delete` method declarations. +// We'll override the default trait malloc ourselves without a macro. +#undef new +#undef delete +#undef malloc +#undef free +#else +#include <atomic> // Requires C++11. Sorry VS2010. +#include <cassert> +#endif +#include <cstddef> // for max_align_t +#include <cstdint> +#include <cstdlib> +#include <type_traits> +#include <algorithm> +#include <utility> +#include <limits> +#include <climits> // for CHAR_BIT +#include <array> +#include <thread> // partly for __WINPTHREADS_VERSION if on MinGW-w64 w/ POSIX threading +#include <mutex> // used for thread exit synchronization + +// Platform-specific definitions of a numeric thread ID type and an invalid value +namespace moodycamel { namespace details { + template<typename thread_id_t> struct thread_id_converter { + typedef thread_id_t thread_id_numeric_size_t; + typedef thread_id_t thread_id_hash_t; + static thread_id_hash_t prehash(thread_id_t const& x) { return x; } + }; +} } +#if defined(MCDBGQ_USE_RELACY) +namespace moodycamel { namespace details { + typedef std::uint32_t thread_id_t; + static const thread_id_t invalid_thread_id = 0xFFFFFFFFU; + static const thread_id_t invalid_thread_id2 = 0xFFFFFFFEU; + static inline thread_id_t thread_id() { return rl::thread_index(); } +} } +#elif defined(_WIN32) || defined(__WINDOWS__) || defined(__WIN32__) +// No sense pulling in windows.h in a header, we'll manually declare the function +// we use and rely on backwards-compatibility for this not to break +extern "C" __declspec(dllimport) unsigned long __stdcall GetCurrentThreadId(void); +namespace moodycamel { namespace details { + static_assert(sizeof(unsigned long) == sizeof(std::uint32_t), "Expected size of unsigned long to be 32 bits on Windows"); + typedef std::uint32_t thread_id_t; + static const thread_id_t invalid_thread_id = 0; // See http://blogs.msdn.com/b/oldnewthing/archive/2004/02/23/78395.aspx + static const thread_id_t invalid_thread_id2 = 0xFFFFFFFFU; // Not technically guaranteed to be invalid, but is never used in practice. Note that all Win32 thread IDs are presently multiples of 4. + static inline thread_id_t thread_id() { return static_cast<thread_id_t>(::GetCurrentThreadId()); } +} } +#elif defined(__arm__) || defined(_M_ARM) || defined(__aarch64__) || (defined(__APPLE__) && TARGET_OS_IPHONE) || defined(__MVS__) || defined(MOODYCAMEL_NO_THREAD_LOCAL) +namespace moodycamel { namespace details { + static_assert(sizeof(std::thread::id) == 4 || sizeof(std::thread::id) == 8, "std::thread::id is expected to be either 4 or 8 bytes"); + + typedef std::thread::id thread_id_t; + static const thread_id_t invalid_thread_id; // Default ctor creates invalid ID + + // Note we don't define a invalid_thread_id2 since std::thread::id doesn't have one; it's + // only used if MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED is defined anyway, which it won't + // be. + static inline thread_id_t thread_id() { return std::this_thread::get_id(); } + + template<std::size_t> struct thread_id_size { }; + template<> struct thread_id_size<4> { typedef std::uint32_t numeric_t; }; + template<> struct thread_id_size<8> { typedef std::uint64_t numeric_t; }; + + template<> struct thread_id_converter<thread_id_t> { + typedef thread_id_size<sizeof(thread_id_t)>::numeric_t thread_id_numeric_size_t; +#ifndef __APPLE__ + typedef std::size_t thread_id_hash_t; +#else + typedef thread_id_numeric_size_t thread_id_hash_t; +#endif + + static thread_id_hash_t prehash(thread_id_t const& x) + { +#ifndef __APPLE__ + return std::hash<std::thread::id>()(x); +#else + return *reinterpret_cast<thread_id_hash_t const*>(&x); +#endif + } + }; +} } +#else +// Use a nice trick from this answer: http://stackoverflow.com/a/8438730/21475 +// In order to get a numeric thread ID in a platform-independent way, we use a thread-local +// static variable's address as a thread identifier :-) +#if defined(__GNUC__) || defined(__INTEL_COMPILER) +#define MOODYCAMEL_THREADLOCAL __thread +#elif defined(_MSC_VER) +#define MOODYCAMEL_THREADLOCAL __declspec(thread) +#else +// Assume C++11 compliant compiler +#define MOODYCAMEL_THREADLOCAL thread_local +#endif +namespace moodycamel { namespace details { + typedef std::uintptr_t thread_id_t; + static const thread_id_t invalid_thread_id = 0; // Address can't be nullptr + static const thread_id_t invalid_thread_id2 = 1; // Member accesses off a null pointer are also generally invalid. Plus it's not aligned. + inline thread_id_t thread_id() { static MOODYCAMEL_THREADLOCAL int x; return reinterpret_cast<thread_id_t>(&x); } +} } +#endif + +// Constexpr if +#ifndef MOODYCAMEL_CONSTEXPR_IF +#if (defined(_MSC_VER) && defined(_HAS_CXX17) && _HAS_CXX17) || __cplusplus > 201402L +#define MOODYCAMEL_CONSTEXPR_IF if constexpr +#define MOODYCAMEL_MAYBE_UNUSED [[maybe_unused]] +#else +#define MOODYCAMEL_CONSTEXPR_IF if +#define MOODYCAMEL_MAYBE_UNUSED +#endif +#endif + +// Exceptions +#ifndef MOODYCAMEL_EXCEPTIONS_ENABLED +#if (defined(_MSC_VER) && defined(_CPPUNWIND)) || (defined(__GNUC__) && defined(__EXCEPTIONS)) || (!defined(_MSC_VER) && !defined(__GNUC__)) +#define MOODYCAMEL_EXCEPTIONS_ENABLED +#endif +#endif +#ifdef MOODYCAMEL_EXCEPTIONS_ENABLED +#define MOODYCAMEL_TRY try +#define MOODYCAMEL_CATCH(...) catch(__VA_ARGS__) +#define MOODYCAMEL_RETHROW throw +#define MOODYCAMEL_THROW(expr) throw (expr) +#else +#define MOODYCAMEL_TRY MOODYCAMEL_CONSTEXPR_IF (true) +#define MOODYCAMEL_CATCH(...) else MOODYCAMEL_CONSTEXPR_IF (false) +#define MOODYCAMEL_RETHROW +#define MOODYCAMEL_THROW(expr) +#endif + +#ifndef MOODYCAMEL_NOEXCEPT +#if !defined(MOODYCAMEL_EXCEPTIONS_ENABLED) +#define MOODYCAMEL_NOEXCEPT +#define MOODYCAMEL_NOEXCEPT_CTOR(type, valueType, expr) true +#define MOODYCAMEL_NOEXCEPT_ASSIGN(type, valueType, expr) true +#elif defined(_MSC_VER) && defined(_NOEXCEPT) && _MSC_VER < 1800 +// VS2012's std::is_nothrow_[move_]constructible is broken and returns true when it shouldn't :-( +// We have to assume *all* non-trivial constructors may throw on VS2012! +#define MOODYCAMEL_NOEXCEPT _NOEXCEPT +#define MOODYCAMEL_NOEXCEPT_CTOR(type, valueType, expr) (std::is_rvalue_reference<valueType>::value && std::is_move_constructible<type>::value ? std::is_trivially_move_constructible<type>::value : std::is_trivially_copy_constructible<type>::value) +#define MOODYCAMEL_NOEXCEPT_ASSIGN(type, valueType, expr) ((std::is_rvalue_reference<valueType>::value && std::is_move_assignable<type>::value ? std::is_trivially_move_assignable<type>::value || std::is_nothrow_move_assignable<type>::value : std::is_trivially_copy_assignable<type>::value || std::is_nothrow_copy_assignable<type>::value) && MOODYCAMEL_NOEXCEPT_CTOR(type, valueType, expr)) +#elif defined(_MSC_VER) && defined(_NOEXCEPT) && _MSC_VER < 1900 +#define MOODYCAMEL_NOEXCEPT _NOEXCEPT +#define MOODYCAMEL_NOEXCEPT_CTOR(type, valueType, expr) (std::is_rvalue_reference<valueType>::value && std::is_move_constructible<type>::value ? std::is_trivially_move_constructible<type>::value || std::is_nothrow_move_constructible<type>::value : std::is_trivially_copy_constructible<type>::value || std::is_nothrow_copy_constructible<type>::value) +#define MOODYCAMEL_NOEXCEPT_ASSIGN(type, valueType, expr) ((std::is_rvalue_reference<valueType>::value && std::is_move_assignable<type>::value ? std::is_trivially_move_assignable<type>::value || std::is_nothrow_move_assignable<type>::value : std::is_trivially_copy_assignable<type>::value || std::is_nothrow_copy_assignable<type>::value) && MOODYCAMEL_NOEXCEPT_CTOR(type, valueType, expr)) +#else +#define MOODYCAMEL_NOEXCEPT noexcept +#define MOODYCAMEL_NOEXCEPT_CTOR(type, valueType, expr) noexcept(expr) +#define MOODYCAMEL_NOEXCEPT_ASSIGN(type, valueType, expr) noexcept(expr) +#endif +#endif + +#ifndef MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED +#ifdef MCDBGQ_USE_RELACY +#define MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED +#else +// VS2013 doesn't support `thread_local`, and MinGW-w64 w/ POSIX threading has a crippling bug: http://sourceforge.net/p/mingw-w64/bugs/445 +// g++ <=4.7 doesn't support thread_local either. +// Finally, iOS/ARM doesn't have support for it either, and g++/ARM allows it to compile but it's unconfirmed to actually work +#if (!defined(_MSC_VER) || _MSC_VER >= 1900) && (!defined(__MINGW32__) && !defined(__MINGW64__) || !defined(__WINPTHREADS_VERSION)) && (!defined(__GNUC__) || __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)) && (!defined(__APPLE__) || !TARGET_OS_IPHONE) && !defined(__arm__) && !defined(_M_ARM) && !defined(__aarch64__) && !defined(__MVS__) +// Assume `thread_local` is fully supported in all other C++11 compilers/platforms +#define MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED // tentatively enabled for now; years ago several users report having problems with it on +#endif +#endif +#endif + +// VS2012 doesn't support deleted functions. +// In this case, we declare the function normally but don't define it. A link error will be generated if the function is called. +#ifndef MOODYCAMEL_DELETE_FUNCTION +#if defined(_MSC_VER) && _MSC_VER < 1800 +#define MOODYCAMEL_DELETE_FUNCTION +#else +#define MOODYCAMEL_DELETE_FUNCTION = delete +#endif +#endif + +namespace moodycamel { namespace details { +#ifndef MOODYCAMEL_ALIGNAS +// VS2013 doesn't support alignas or alignof, and align() requires a constant literal +#if defined(_MSC_VER) && _MSC_VER <= 1800 +#define MOODYCAMEL_ALIGNAS(alignment) __declspec(align(alignment)) +#define MOODYCAMEL_ALIGNOF(obj) __alignof(obj) +#define MOODYCAMEL_ALIGNED_TYPE_LIKE(T, obj) typename details::Vs2013Aligned<std::alignment_of<obj>::value, T>::type + template<int Align, typename T> struct Vs2013Aligned { }; // default, unsupported alignment + template<typename T> struct Vs2013Aligned<1, T> { typedef __declspec(align(1)) T type; }; + template<typename T> struct Vs2013Aligned<2, T> { typedef __declspec(align(2)) T type; }; + template<typename T> struct Vs2013Aligned<4, T> { typedef __declspec(align(4)) T type; }; + template<typename T> struct Vs2013Aligned<8, T> { typedef __declspec(align(8)) T type; }; + template<typename T> struct Vs2013Aligned<16, T> { typedef __declspec(align(16)) T type; }; + template<typename T> struct Vs2013Aligned<32, T> { typedef __declspec(align(32)) T type; }; + template<typename T> struct Vs2013Aligned<64, T> { typedef __declspec(align(64)) T type; }; + template<typename T> struct Vs2013Aligned<128, T> { typedef __declspec(align(128)) T type; }; + template<typename T> struct Vs2013Aligned<256, T> { typedef __declspec(align(256)) T type; }; +#else + template<typename T> struct identity { typedef T type; }; +#define MOODYCAMEL_ALIGNAS(alignment) alignas(alignment) +#define MOODYCAMEL_ALIGNOF(obj) alignof(obj) +#define MOODYCAMEL_ALIGNED_TYPE_LIKE(T, obj) alignas(alignof(obj)) typename details::identity<T>::type +#endif +#endif +} } + + +// TSAN can false report races in lock-free code. To enable TSAN to be used from projects that use this one, +// we can apply per-function compile-time suppression. +// See https://clang.llvm.org/docs/ThreadSanitizer.html#has-feature-thread-sanitizer +#define MOODYCAMEL_NO_TSAN +#if defined(__has_feature) + #if __has_feature(thread_sanitizer) + #undef MOODYCAMEL_NO_TSAN + #define MOODYCAMEL_NO_TSAN __attribute__((no_sanitize("thread"))) + #endif // TSAN +#endif // TSAN + +// Compiler-specific likely/unlikely hints +namespace moodycamel { namespace details { +#if defined(__GNUC__) + static inline bool (likely)(bool x) { return __builtin_expect((x), true); } + static inline bool (unlikely)(bool x) { return __builtin_expect((x), false); } +#else + static inline bool (likely)(bool x) { return x; } + static inline bool (unlikely)(bool x) { return x; } +#endif +} } + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG +#include "internal/concurrentqueue_internal_debug.h" +#endif + +namespace moodycamel { +namespace details { + template<typename T> + struct const_numeric_max { + static_assert(std::is_integral<T>::value, "const_numeric_max can only be used with integers"); + static const T value = std::numeric_limits<T>::is_signed + ? (static_cast<T>(1) << (sizeof(T) * CHAR_BIT - 1)) - static_cast<T>(1) + : static_cast<T>(-1); + }; + +#if defined(__GLIBCXX__) + typedef ::max_align_t std_max_align_t; // libstdc++ forgot to add it to std:: for a while +#else + typedef std::max_align_t std_max_align_t; // Others (e.g. MSVC) insist it can *only* be accessed via std:: +#endif + + // Some platforms have incorrectly set max_align_t to a type with <8 bytes alignment even while supporting + // 8-byte aligned scalar values (*cough* 32-bit iOS). Work around this with our own union. See issue #64. + typedef union { + std_max_align_t x; + long long y; + void* z; + } max_align_t; +} + +// Default traits for the ConcurrentQueue. To change some of the +// traits without re-implementing all of them, inherit from this +// struct and shadow the declarations you wish to be different; +// since the traits are used as a template type parameter, the +// shadowed declarations will be used where defined, and the defaults +// otherwise. +struct ConcurrentQueueDefaultTraits +{ + // General-purpose size type. std::size_t is strongly recommended. + typedef std::size_t size_t; + + // The type used for the enqueue and dequeue indices. Must be at least as + // large as size_t. Should be significantly larger than the number of elements + // you expect to hold at once, especially if you have a high turnover rate; + // for example, on 32-bit x86, if you expect to have over a hundred million + // elements or pump several million elements through your queue in a very + // short space of time, using a 32-bit type *may* trigger a race condition. + // A 64-bit int type is recommended in that case, and in practice will + // prevent a race condition no matter the usage of the queue. Note that + // whether the queue is lock-free with a 64-int type depends on the whether + // std::atomic<std::uint64_t> is lock-free, which is platform-specific. + typedef std::size_t index_t; + + // Internally, all elements are enqueued and dequeued from multi-element + // blocks; this is the smallest controllable unit. If you expect few elements + // but many producers, a smaller block size should be favoured. For few producers + // and/or many elements, a larger block size is preferred. A sane default + // is provided. Must be a power of 2. + static const size_t BLOCK_SIZE = 32; + + // For explicit producers (i.e. when using a producer token), the block is + // checked for being empty by iterating through a list of flags, one per element. + // For large block sizes, this is too inefficient, and switching to an atomic + // counter-based approach is faster. The switch is made for block sizes strictly + // larger than this threshold. + static const size_t EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD = 32; + + // How many full blocks can be expected for a single explicit producer? This should + // reflect that number's maximum for optimal performance. Must be a power of 2. + static const size_t EXPLICIT_INITIAL_INDEX_SIZE = 32; + + // How many full blocks can be expected for a single implicit producer? This should + // reflect that number's maximum for optimal performance. Must be a power of 2. + static const size_t IMPLICIT_INITIAL_INDEX_SIZE = 32; + + // The initial size of the hash table mapping thread IDs to implicit producers. + // Note that the hash is resized every time it becomes half full. + // Must be a power of two, and either 0 or at least 1. If 0, implicit production + // (using the enqueue methods without an explicit producer token) is disabled. + static const size_t INITIAL_IMPLICIT_PRODUCER_HASH_SIZE = 32; + + // Controls the number of items that an explicit consumer (i.e. one with a token) + // must consume before it causes all consumers to rotate and move on to the next + // internal queue. + static const std::uint32_t EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE = 256; + + // The maximum number of elements (inclusive) that can be enqueued to a sub-queue. + // Enqueue operations that would cause this limit to be surpassed will fail. Note + // that this limit is enforced at the block level (for performance reasons), i.e. + // it's rounded up to the nearest block size. + static const size_t MAX_SUBQUEUE_SIZE = details::const_numeric_max<size_t>::value; + + // The number of times to spin before sleeping when waiting on a semaphore. + // Recommended values are on the order of 1000-10000 unless the number of + // consumer threads exceeds the number of idle cores (in which case try 0-100). + // Only affects instances of the BlockingConcurrentQueue. + static const int MAX_SEMA_SPINS = 10000; + + // Whether to recycle dynamically-allocated blocks into an internal free list or + // not. If false, only pre-allocated blocks (controlled by the constructor + // arguments) will be recycled, and all others will be `free`d back to the heap. + // Note that blocks consumed by explicit producers are only freed on destruction + // of the queue (not following destruction of the token) regardless of this trait. + static const bool RECYCLE_ALLOCATED_BLOCKS = false; + + +#ifndef MCDBGQ_USE_RELACY + // Memory allocation can be customized if needed. + // malloc should return nullptr on failure, and handle alignment like std::malloc. +#if defined(malloc) || defined(free) + // Gah, this is 2015, stop defining macros that break standard code already! + // Work around malloc/free being special macros: + static inline void* WORKAROUND_malloc(size_t size) { return malloc(size); } + static inline void WORKAROUND_free(void* ptr) { return free(ptr); } + static inline void* (malloc)(size_t size) { return WORKAROUND_malloc(size); } + static inline void (free)(void* ptr) { return WORKAROUND_free(ptr); } +#else + static inline void* malloc(size_t size) { return std::malloc(size); } + static inline void free(void* ptr) { return std::free(ptr); } +#endif +#else + // Debug versions when running under the Relacy race detector (ignore + // these in user code) + static inline void* malloc(size_t size) { return rl::rl_malloc(size, $); } + static inline void free(void* ptr) { return rl::rl_free(ptr, $); } +#endif +}; + + +// When producing or consuming many elements, the most efficient way is to: +// 1) Use one of the bulk-operation methods of the queue with a token +// 2) Failing that, use the bulk-operation methods without a token +// 3) Failing that, create a token and use that with the single-item methods +// 4) Failing that, use the single-parameter methods of the queue +// Having said that, don't create tokens willy-nilly -- ideally there should be +// a maximum of one token per thread (of each kind). +struct ProducerToken; +struct ConsumerToken; + +template<typename T, typename Traits> class ConcurrentQueue; +template<typename T, typename Traits> class BlockingConcurrentQueue; +class ConcurrentQueueTests; + + +namespace details +{ + struct ConcurrentQueueProducerTypelessBase + { + ConcurrentQueueProducerTypelessBase* next; + std::atomic<bool> inactive; + ProducerToken* token; + + ConcurrentQueueProducerTypelessBase() + : next(nullptr), inactive(false), token(nullptr) + { + } + }; + + template<bool use32> struct _hash_32_or_64 { + static inline std::uint32_t hash(std::uint32_t h) + { + // MurmurHash3 finalizer -- see https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp + // Since the thread ID is already unique, all we really want to do is propagate that + // uniqueness evenly across all the bits, so that we can use a subset of the bits while + // reducing collisions significantly + h ^= h >> 16; + h *= 0x85ebca6b; + h ^= h >> 13; + h *= 0xc2b2ae35; + return h ^ (h >> 16); + } + }; + template<> struct _hash_32_or_64<1> { + static inline std::uint64_t hash(std::uint64_t h) + { + h ^= h >> 33; + h *= 0xff51afd7ed558ccd; + h ^= h >> 33; + h *= 0xc4ceb9fe1a85ec53; + return h ^ (h >> 33); + } + }; + template<std::size_t size> struct hash_32_or_64 : public _hash_32_or_64<(size > 4)> { }; + + static inline size_t hash_thread_id(thread_id_t id) + { + static_assert(sizeof(thread_id_t) <= 8, "Expected a platform where thread IDs are at most 64-bit values"); + return static_cast<size_t>(hash_32_or_64<sizeof(thread_id_converter<thread_id_t>::thread_id_hash_t)>::hash( + thread_id_converter<thread_id_t>::prehash(id))); + } + + template<typename T> + static inline bool circular_less_than(T a, T b) + { + static_assert(std::is_integral<T>::value && !std::numeric_limits<T>::is_signed, "circular_less_than is intended to be used only with unsigned integer types"); + return static_cast<T>(a - b) > static_cast<T>(static_cast<T>(1) << (static_cast<T>(sizeof(T) * CHAR_BIT - 1))); + // Note: extra parens around rhs of operator<< is MSVC bug: https://developercommunity2.visualstudio.com/t/C4554-triggers-when-both-lhs-and-rhs-is/10034931 + // silencing the bug requires #pragma warning(disable: 4554) around the calling code and has no effect when done here. + } + + template<typename U> + static inline char* align_for(char* ptr) + { + const std::size_t alignment = std::alignment_of<U>::value; + return ptr + (alignment - (reinterpret_cast<std::uintptr_t>(ptr) % alignment)) % alignment; + } + + template<typename T> + static inline T ceil_to_pow_2(T x) + { + static_assert(std::is_integral<T>::value && !std::numeric_limits<T>::is_signed, "ceil_to_pow_2 is intended to be used only with unsigned integer types"); + + // Adapted from http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2 + --x; + x |= x >> 1; + x |= x >> 2; + x |= x >> 4; + for (std::size_t i = 1; i < sizeof(T); i <<= 1) { + x |= x >> (i << 3); + } + ++x; + return x; + } + + template<typename T> + static inline void swap_relaxed(std::atomic<T>& left, std::atomic<T>& right) + { + T temp = left.load(std::memory_order_relaxed); + left.store(right.load(std::memory_order_relaxed), std::memory_order_relaxed); + right.store(temp, std::memory_order_relaxed); + } + + template<typename T> + static inline T const& nomove(T const& x) + { + return x; + } + + template<bool Enable> + struct nomove_if + { + template<typename T> + static inline T const& eval(T const& x) + { + return x; + } + }; + + template<> + struct nomove_if<false> + { + template<typename U> + static inline auto eval(U&& x) + -> decltype(std::forward<U>(x)) + { + return std::forward<U>(x); + } + }; + + template<typename It> + static inline auto deref_noexcept(It& it) MOODYCAMEL_NOEXCEPT -> decltype(*it) + { + return *it; + } + +#if defined(__clang__) || !defined(__GNUC__) || __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8) + template<typename T> struct is_trivially_destructible : std::is_trivially_destructible<T> { }; +#else + template<typename T> struct is_trivially_destructible : std::has_trivial_destructor<T> { }; +#endif + +#ifdef MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED +#ifdef MCDBGQ_USE_RELACY + typedef RelacyThreadExitListener ThreadExitListener; + typedef RelacyThreadExitNotifier ThreadExitNotifier; +#else + class ThreadExitNotifier; + + struct ThreadExitListener + { + typedef void (*callback_t)(void*); + callback_t callback; + void* userData; + + ThreadExitListener* next; // reserved for use by the ThreadExitNotifier + ThreadExitNotifier* chain; // reserved for use by the ThreadExitNotifier + }; + + class ThreadExitNotifier + { + public: + static void subscribe(ThreadExitListener* listener) + { + auto& tlsInst = instance(); + std::lock_guard<std::mutex> guard(mutex()); + listener->next = tlsInst.tail; + listener->chain = &tlsInst; + tlsInst.tail = listener; + } + + static void unsubscribe(ThreadExitListener* listener) + { + std::lock_guard<std::mutex> guard(mutex()); + if (!listener->chain) { + return; // race with ~ThreadExitNotifier + } + auto& tlsInst = *listener->chain; + listener->chain = nullptr; + ThreadExitListener** prev = &tlsInst.tail; + for (auto ptr = tlsInst.tail; ptr != nullptr; ptr = ptr->next) { + if (ptr == listener) { + *prev = ptr->next; + break; + } + prev = &ptr->next; + } + } + + private: + ThreadExitNotifier() : tail(nullptr) { } + ThreadExitNotifier(ThreadExitNotifier const&) MOODYCAMEL_DELETE_FUNCTION; + ThreadExitNotifier& operator=(ThreadExitNotifier const&) MOODYCAMEL_DELETE_FUNCTION; + + ~ThreadExitNotifier() + { + // This thread is about to exit, let everyone know! + assert(this == &instance() && "If this assert fails, you likely have a buggy compiler! Change the preprocessor conditions such that MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED is no longer defined."); + std::lock_guard<std::mutex> guard(mutex()); + for (auto ptr = tail; ptr != nullptr; ptr = ptr->next) { + ptr->chain = nullptr; + ptr->callback(ptr->userData); + } + } + + // Thread-local + static inline ThreadExitNotifier& instance() + { + static thread_local ThreadExitNotifier notifier; + return notifier; + } + + static inline std::mutex& mutex() + { + // Must be static because the ThreadExitNotifier could be destroyed while unsubscribe is called + static std::mutex mutex; + return mutex; + } + + private: + ThreadExitListener* tail; + }; +#endif +#endif + + template<typename T> struct static_is_lock_free_num { enum { value = 0 }; }; + template<> struct static_is_lock_free_num<signed char> { enum { value = ATOMIC_CHAR_LOCK_FREE }; }; + template<> struct static_is_lock_free_num<short> { enum { value = ATOMIC_SHORT_LOCK_FREE }; }; + template<> struct static_is_lock_free_num<int> { enum { value = ATOMIC_INT_LOCK_FREE }; }; + template<> struct static_is_lock_free_num<long> { enum { value = ATOMIC_LONG_LOCK_FREE }; }; + template<> struct static_is_lock_free_num<long long> { enum { value = ATOMIC_LLONG_LOCK_FREE }; }; + template<typename T> struct static_is_lock_free : static_is_lock_free_num<typename std::make_signed<T>::type> { }; + template<> struct static_is_lock_free<bool> { enum { value = ATOMIC_BOOL_LOCK_FREE }; }; + template<typename U> struct static_is_lock_free<U*> { enum { value = ATOMIC_POINTER_LOCK_FREE }; }; +} + + +struct ProducerToken +{ + template<typename T, typename Traits> + explicit ProducerToken(ConcurrentQueue<T, Traits>& queue); + + template<typename T, typename Traits> + explicit ProducerToken(BlockingConcurrentQueue<T, Traits>& queue); + + ProducerToken(ProducerToken&& other) MOODYCAMEL_NOEXCEPT + : producer(other.producer) + { + other.producer = nullptr; + if (producer != nullptr) { + producer->token = this; + } + } + + inline ProducerToken& operator=(ProducerToken&& other) MOODYCAMEL_NOEXCEPT + { + swap(other); + return *this; + } + + void swap(ProducerToken& other) MOODYCAMEL_NOEXCEPT + { + std::swap(producer, other.producer); + if (producer != nullptr) { + producer->token = this; + } + if (other.producer != nullptr) { + other.producer->token = &other; + } + } + + // A token is always valid unless: + // 1) Memory allocation failed during construction + // 2) It was moved via the move constructor + // (Note: assignment does a swap, leaving both potentially valid) + // 3) The associated queue was destroyed + // Note that if valid() returns true, that only indicates + // that the token is valid for use with a specific queue, + // but not which one; that's up to the user to track. + inline bool valid() const { return producer != nullptr; } + + ~ProducerToken() + { + if (producer != nullptr) { + producer->token = nullptr; + producer->inactive.store(true, std::memory_order_release); + } + } + + // Disable copying and assignment + ProducerToken(ProducerToken const&) MOODYCAMEL_DELETE_FUNCTION; + ProducerToken& operator=(ProducerToken const&) MOODYCAMEL_DELETE_FUNCTION; + +private: + template<typename T, typename Traits> friend class ConcurrentQueue; + friend class ConcurrentQueueTests; + +protected: + details::ConcurrentQueueProducerTypelessBase* producer; +}; + + +struct ConsumerToken +{ + template<typename T, typename Traits> + explicit ConsumerToken(ConcurrentQueue<T, Traits>& q); + + template<typename T, typename Traits> + explicit ConsumerToken(BlockingConcurrentQueue<T, Traits>& q); + + ConsumerToken(ConsumerToken&& other) MOODYCAMEL_NOEXCEPT + : initialOffset(other.initialOffset), lastKnownGlobalOffset(other.lastKnownGlobalOffset), itemsConsumedFromCurrent(other.itemsConsumedFromCurrent), currentProducer(other.currentProducer), desiredProducer(other.desiredProducer) + { + } + + inline ConsumerToken& operator=(ConsumerToken&& other) MOODYCAMEL_NOEXCEPT + { + swap(other); + return *this; + } + + void swap(ConsumerToken& other) MOODYCAMEL_NOEXCEPT + { + std::swap(initialOffset, other.initialOffset); + std::swap(lastKnownGlobalOffset, other.lastKnownGlobalOffset); + std::swap(itemsConsumedFromCurrent, other.itemsConsumedFromCurrent); + std::swap(currentProducer, other.currentProducer); + std::swap(desiredProducer, other.desiredProducer); + } + + // Disable copying and assignment + ConsumerToken(ConsumerToken const&) MOODYCAMEL_DELETE_FUNCTION; + ConsumerToken& operator=(ConsumerToken const&) MOODYCAMEL_DELETE_FUNCTION; + +private: + template<typename T, typename Traits> friend class ConcurrentQueue; + friend class ConcurrentQueueTests; + +private: // but shared with ConcurrentQueue + std::uint32_t initialOffset; + std::uint32_t lastKnownGlobalOffset; + std::uint32_t itemsConsumedFromCurrent; + details::ConcurrentQueueProducerTypelessBase* currentProducer; + details::ConcurrentQueueProducerTypelessBase* desiredProducer; +}; + +// Need to forward-declare this swap because it's in a namespace. +// See http://stackoverflow.com/questions/4492062/why-does-a-c-friend-class-need-a-forward-declaration-only-in-other-namespaces +template<typename T, typename Traits> +inline void swap(typename ConcurrentQueue<T, Traits>::ImplicitProducerKVP& a, typename ConcurrentQueue<T, Traits>::ImplicitProducerKVP& b) MOODYCAMEL_NOEXCEPT; + + +template<typename T, typename Traits = ConcurrentQueueDefaultTraits> +class ConcurrentQueue +{ +public: + typedef ::moodycamel::ProducerToken producer_token_t; + typedef ::moodycamel::ConsumerToken consumer_token_t; + + typedef typename Traits::index_t index_t; + typedef typename Traits::size_t size_t; + + static const size_t BLOCK_SIZE = static_cast<size_t>(Traits::BLOCK_SIZE); + static const size_t EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD = static_cast<size_t>(Traits::EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD); + static const size_t EXPLICIT_INITIAL_INDEX_SIZE = static_cast<size_t>(Traits::EXPLICIT_INITIAL_INDEX_SIZE); + static const size_t IMPLICIT_INITIAL_INDEX_SIZE = static_cast<size_t>(Traits::IMPLICIT_INITIAL_INDEX_SIZE); + static const size_t INITIAL_IMPLICIT_PRODUCER_HASH_SIZE = static_cast<size_t>(Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE); + static const std::uint32_t EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE = static_cast<std::uint32_t>(Traits::EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE); +#ifdef _MSC_VER +#pragma warning(push) +#pragma warning(disable: 4307) // + integral constant overflow (that's what the ternary expression is for!) +#pragma warning(disable: 4309) // static_cast: Truncation of constant value +#endif + static const size_t MAX_SUBQUEUE_SIZE = (details::const_numeric_max<size_t>::value - static_cast<size_t>(Traits::MAX_SUBQUEUE_SIZE) < BLOCK_SIZE) ? details::const_numeric_max<size_t>::value : ((static_cast<size_t>(Traits::MAX_SUBQUEUE_SIZE) + (BLOCK_SIZE - 1)) / BLOCK_SIZE * BLOCK_SIZE); +#ifdef _MSC_VER +#pragma warning(pop) +#endif + + static_assert(!std::numeric_limits<size_t>::is_signed && std::is_integral<size_t>::value, "Traits::size_t must be an unsigned integral type"); + static_assert(!std::numeric_limits<index_t>::is_signed && std::is_integral<index_t>::value, "Traits::index_t must be an unsigned integral type"); + static_assert(sizeof(index_t) >= sizeof(size_t), "Traits::index_t must be at least as wide as Traits::size_t"); + static_assert((BLOCK_SIZE > 1) && !(BLOCK_SIZE & (BLOCK_SIZE - 1)), "Traits::BLOCK_SIZE must be a power of 2 (and at least 2)"); + static_assert((EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD > 1) && !(EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD & (EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD - 1)), "Traits::EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD must be a power of 2 (and greater than 1)"); + static_assert((EXPLICIT_INITIAL_INDEX_SIZE > 1) && !(EXPLICIT_INITIAL_INDEX_SIZE & (EXPLICIT_INITIAL_INDEX_SIZE - 1)), "Traits::EXPLICIT_INITIAL_INDEX_SIZE must be a power of 2 (and greater than 1)"); + static_assert((IMPLICIT_INITIAL_INDEX_SIZE > 1) && !(IMPLICIT_INITIAL_INDEX_SIZE & (IMPLICIT_INITIAL_INDEX_SIZE - 1)), "Traits::IMPLICIT_INITIAL_INDEX_SIZE must be a power of 2 (and greater than 1)"); + static_assert((INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) || !(INITIAL_IMPLICIT_PRODUCER_HASH_SIZE & (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE - 1)), "Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE must be a power of 2"); + static_assert(INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0 || INITIAL_IMPLICIT_PRODUCER_HASH_SIZE >= 1, "Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE must be at least 1 (or 0 to disable implicit enqueueing)"); + +public: + // Creates a queue with at least `capacity` element slots; note that the + // actual number of elements that can be inserted without additional memory + // allocation depends on the number of producers and the block size (e.g. if + // the block size is equal to `capacity`, only a single block will be allocated + // up-front, which means only a single producer will be able to enqueue elements + // without an extra allocation -- blocks aren't shared between producers). + // This method is not thread safe -- it is up to the user to ensure that the + // queue is fully constructed before it starts being used by other threads (this + // includes making the memory effects of construction visible, possibly with a + // memory barrier). + explicit ConcurrentQueue(size_t capacity = 32 * BLOCK_SIZE) + : producerListTail(nullptr), + producerCount(0), + initialBlockPoolIndex(0), + nextExplicitConsumerId(0), + globalExplicitConsumerOffset(0) + { + implicitProducerHashResizeInProgress.clear(std::memory_order_relaxed); + populate_initial_implicit_producer_hash(); + populate_initial_block_list(capacity / BLOCK_SIZE + ((capacity & (BLOCK_SIZE - 1)) == 0 ? 0 : 1)); + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG + // Track all the producers using a fully-resolved typed list for + // each kind; this makes it possible to debug them starting from + // the root queue object (otherwise wacky casts are needed that + // don't compile in the debugger's expression evaluator). + explicitProducers.store(nullptr, std::memory_order_relaxed); + implicitProducers.store(nullptr, std::memory_order_relaxed); +#endif + } + + // Computes the correct amount of pre-allocated blocks for you based + // on the minimum number of elements you want available at any given + // time, and the maximum concurrent number of each type of producer. + ConcurrentQueue(size_t minCapacity, size_t maxExplicitProducers, size_t maxImplicitProducers) + : producerListTail(nullptr), + producerCount(0), + initialBlockPoolIndex(0), + nextExplicitConsumerId(0), + globalExplicitConsumerOffset(0) + { + implicitProducerHashResizeInProgress.clear(std::memory_order_relaxed); + populate_initial_implicit_producer_hash(); + size_t blocks = (((minCapacity + BLOCK_SIZE - 1) / BLOCK_SIZE) - 1) * (maxExplicitProducers + 1) + 2 * (maxExplicitProducers + maxImplicitProducers); + populate_initial_block_list(blocks); + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG + explicitProducers.store(nullptr, std::memory_order_relaxed); + implicitProducers.store(nullptr, std::memory_order_relaxed); +#endif + } + + // Note: The queue should not be accessed concurrently while it's + // being deleted. It's up to the user to synchronize this. + // This method is not thread safe. + ~ConcurrentQueue() + { + // Destroy producers + auto ptr = producerListTail.load(std::memory_order_relaxed); + while (ptr != nullptr) { + auto next = ptr->next_prod(); + if (ptr->token != nullptr) { + ptr->token->producer = nullptr; + } + destroy(ptr); + ptr = next; + } + + // Destroy implicit producer hash tables + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE != 0) { + auto hash = implicitProducerHash.load(std::memory_order_relaxed); + while (hash != nullptr) { + auto prev = hash->prev; + if (prev != nullptr) { // The last hash is part of this object and was not allocated dynamically + for (size_t i = 0; i != hash->capacity; ++i) { + hash->entries[i].~ImplicitProducerKVP(); + } + hash->~ImplicitProducerHash(); + (Traits::free)(hash); + } + hash = prev; + } + } + + // Destroy global free list + auto block = freeList.head_unsafe(); + while (block != nullptr) { + auto next = block->freeListNext.load(std::memory_order_relaxed); + if (block->dynamicallyAllocated) { + destroy(block); + } + block = next; + } + + // Destroy initial free list + destroy_array(initialBlockPool, initialBlockPoolSize); + } + + // Disable copying and copy assignment + ConcurrentQueue(ConcurrentQueue const&) MOODYCAMEL_DELETE_FUNCTION; + ConcurrentQueue& operator=(ConcurrentQueue const&) MOODYCAMEL_DELETE_FUNCTION; + + // Moving is supported, but note that it is *not* a thread-safe operation. + // Nobody can use the queue while it's being moved, and the memory effects + // of that move must be propagated to other threads before they can use it. + // Note: When a queue is moved, its tokens are still valid but can only be + // used with the destination queue (i.e. semantically they are moved along + // with the queue itself). + ConcurrentQueue(ConcurrentQueue&& other) MOODYCAMEL_NOEXCEPT + : producerListTail(other.producerListTail.load(std::memory_order_relaxed)), + producerCount(other.producerCount.load(std::memory_order_relaxed)), + initialBlockPoolIndex(other.initialBlockPoolIndex.load(std::memory_order_relaxed)), + initialBlockPool(other.initialBlockPool), + initialBlockPoolSize(other.initialBlockPoolSize), + freeList(std::move(other.freeList)), + nextExplicitConsumerId(other.nextExplicitConsumerId.load(std::memory_order_relaxed)), + globalExplicitConsumerOffset(other.globalExplicitConsumerOffset.load(std::memory_order_relaxed)) + { + // Move the other one into this, and leave the other one as an empty queue + implicitProducerHashResizeInProgress.clear(std::memory_order_relaxed); + populate_initial_implicit_producer_hash(); + swap_implicit_producer_hashes(other); + + other.producerListTail.store(nullptr, std::memory_order_relaxed); + other.producerCount.store(0, std::memory_order_relaxed); + other.nextExplicitConsumerId.store(0, std::memory_order_relaxed); + other.globalExplicitConsumerOffset.store(0, std::memory_order_relaxed); + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG + explicitProducers.store(other.explicitProducers.load(std::memory_order_relaxed), std::memory_order_relaxed); + other.explicitProducers.store(nullptr, std::memory_order_relaxed); + implicitProducers.store(other.implicitProducers.load(std::memory_order_relaxed), std::memory_order_relaxed); + other.implicitProducers.store(nullptr, std::memory_order_relaxed); +#endif + + other.initialBlockPoolIndex.store(0, std::memory_order_relaxed); + other.initialBlockPoolSize = 0; + other.initialBlockPool = nullptr; + + reown_producers(); + } + + inline ConcurrentQueue& operator=(ConcurrentQueue&& other) MOODYCAMEL_NOEXCEPT + { + return swap_internal(other); + } + + // Swaps this queue's state with the other's. Not thread-safe. + // Swapping two queues does not invalidate their tokens, however + // the tokens that were created for one queue must be used with + // only the swapped queue (i.e. the tokens are tied to the + // queue's movable state, not the object itself). + inline void swap(ConcurrentQueue& other) MOODYCAMEL_NOEXCEPT + { + swap_internal(other); + } + +private: + ConcurrentQueue& swap_internal(ConcurrentQueue& other) + { + if (this == &other) { + return *this; + } + + details::swap_relaxed(producerListTail, other.producerListTail); + details::swap_relaxed(producerCount, other.producerCount); + details::swap_relaxed(initialBlockPoolIndex, other.initialBlockPoolIndex); + std::swap(initialBlockPool, other.initialBlockPool); + std::swap(initialBlockPoolSize, other.initialBlockPoolSize); + freeList.swap(other.freeList); + details::swap_relaxed(nextExplicitConsumerId, other.nextExplicitConsumerId); + details::swap_relaxed(globalExplicitConsumerOffset, other.globalExplicitConsumerOffset); + + swap_implicit_producer_hashes(other); + + reown_producers(); + other.reown_producers(); + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG + details::swap_relaxed(explicitProducers, other.explicitProducers); + details::swap_relaxed(implicitProducers, other.implicitProducers); +#endif + + return *this; + } + +public: + // Enqueues a single item (by copying it). + // Allocates memory if required. Only fails if memory allocation fails (or implicit + // production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0, + // or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed). + // Thread-safe. + inline bool enqueue(T const& item) + { + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) return false; + else return inner_enqueue<CanAlloc>(item); + } + + // Enqueues a single item (by moving it, if possible). + // Allocates memory if required. Only fails if memory allocation fails (or implicit + // production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0, + // or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed). + // Thread-safe. + inline bool enqueue(T&& item) + { + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) return false; + else return inner_enqueue<CanAlloc>(std::move(item)); + } + + // Enqueues a single item (by copying it) using an explicit producer token. + // Allocates memory if required. Only fails if memory allocation fails (or + // Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed). + // Thread-safe. + inline bool enqueue(producer_token_t const& token, T const& item) + { + return inner_enqueue<CanAlloc>(token, item); + } + + // Enqueues a single item (by moving it, if possible) using an explicit producer token. + // Allocates memory if required. Only fails if memory allocation fails (or + // Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed). + // Thread-safe. + inline bool enqueue(producer_token_t const& token, T&& item) + { + return inner_enqueue<CanAlloc>(token, std::move(item)); + } + + // Enqueues several items. + // Allocates memory if required. Only fails if memory allocation fails (or + // implicit production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE + // is 0, or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed). + // Note: Use std::make_move_iterator if the elements should be moved instead of copied. + // Thread-safe. + template<typename It> + bool enqueue_bulk(It itemFirst, size_t count) + { + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) return false; + else return inner_enqueue_bulk<CanAlloc>(itemFirst, count); + } + + // Enqueues several items using an explicit producer token. + // Allocates memory if required. Only fails if memory allocation fails + // (or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed). + // Note: Use std::make_move_iterator if the elements should be moved + // instead of copied. + // Thread-safe. + template<typename It> + bool enqueue_bulk(producer_token_t const& token, It itemFirst, size_t count) + { + return inner_enqueue_bulk<CanAlloc>(token, itemFirst, count); + } + + // Enqueues a single item (by copying it). + // Does not allocate memory. Fails if not enough room to enqueue (or implicit + // production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE + // is 0). + // Thread-safe. + inline bool try_enqueue(T const& item) + { + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) return false; + else return inner_enqueue<CannotAlloc>(item); + } + + // Enqueues a single item (by moving it, if possible). + // Does not allocate memory (except for one-time implicit producer). + // Fails if not enough room to enqueue (or implicit production is + // disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0). + // Thread-safe. + inline bool try_enqueue(T&& item) + { + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) return false; + else return inner_enqueue<CannotAlloc>(std::move(item)); + } + + // Enqueues a single item (by copying it) using an explicit producer token. + // Does not allocate memory. Fails if not enough room to enqueue. + // Thread-safe. + inline bool try_enqueue(producer_token_t const& token, T const& item) + { + return inner_enqueue<CannotAlloc>(token, item); + } + + // Enqueues a single item (by moving it, if possible) using an explicit producer token. + // Does not allocate memory. Fails if not enough room to enqueue. + // Thread-safe. + inline bool try_enqueue(producer_token_t const& token, T&& item) + { + return inner_enqueue<CannotAlloc>(token, std::move(item)); + } + + // Enqueues several items. + // Does not allocate memory (except for one-time implicit producer). + // Fails if not enough room to enqueue (or implicit production is + // disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0). + // Note: Use std::make_move_iterator if the elements should be moved + // instead of copied. + // Thread-safe. + template<typename It> + bool try_enqueue_bulk(It itemFirst, size_t count) + { + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) return false; + else return inner_enqueue_bulk<CannotAlloc>(itemFirst, count); + } + + // Enqueues several items using an explicit producer token. + // Does not allocate memory. Fails if not enough room to enqueue. + // Note: Use std::make_move_iterator if the elements should be moved + // instead of copied. + // Thread-safe. + template<typename It> + bool try_enqueue_bulk(producer_token_t const& token, It itemFirst, size_t count) + { + return inner_enqueue_bulk<CannotAlloc>(token, itemFirst, count); + } + + + + // Attempts to dequeue from the queue. + // Returns false if all producer streams appeared empty at the time they + // were checked (so, the queue is likely but not guaranteed to be empty). + // Never allocates. Thread-safe. + template<typename U> + bool try_dequeue(U& item) + { + // Instead of simply trying each producer in turn (which could cause needless contention on the first + // producer), we score them heuristically. + size_t nonEmptyCount = 0; + ProducerBase* best = nullptr; + size_t bestSize = 0; + for (auto ptr = producerListTail.load(std::memory_order_acquire); nonEmptyCount < 3 && ptr != nullptr; ptr = ptr->next_prod()) { + auto size = ptr->size_approx(); + if (size > 0) { + if (size > bestSize) { + bestSize = size; + best = ptr; + } + ++nonEmptyCount; + } + } + + // If there was at least one non-empty queue but it appears empty at the time + // we try to dequeue from it, we need to make sure every queue's been tried + if (nonEmptyCount > 0) { + if ((details::likely)(best->dequeue(item))) { + return true; + } + for (auto ptr = producerListTail.load(std::memory_order_acquire); ptr != nullptr; ptr = ptr->next_prod()) { + if (ptr != best && ptr->dequeue(item)) { + return true; + } + } + } + return false; + } + + // Attempts to dequeue from the queue. + // Returns false if all producer streams appeared empty at the time they + // were checked (so, the queue is likely but not guaranteed to be empty). + // This differs from the try_dequeue(item) method in that this one does + // not attempt to reduce contention by interleaving the order that producer + // streams are dequeued from. So, using this method can reduce overall throughput + // under contention, but will give more predictable results in single-threaded + // consumer scenarios. This is mostly only useful for internal unit tests. + // Never allocates. Thread-safe. + template<typename U> + bool try_dequeue_non_interleaved(U& item) + { + for (auto ptr = producerListTail.load(std::memory_order_acquire); ptr != nullptr; ptr = ptr->next_prod()) { + if (ptr->dequeue(item)) { + return true; + } + } + return false; + } + + // Attempts to dequeue from the queue using an explicit consumer token. + // Returns false if all producer streams appeared empty at the time they + // were checked (so, the queue is likely but not guaranteed to be empty). + // Never allocates. Thread-safe. + template<typename U> + bool try_dequeue(consumer_token_t& token, U& item) + { + // The idea is roughly as follows: + // Every 256 items from one producer, make everyone rotate (increase the global offset) -> this means the highest efficiency consumer dictates the rotation speed of everyone else, more or less + // If you see that the global offset has changed, you must reset your consumption counter and move to your designated place + // If there's no items where you're supposed to be, keep moving until you find a producer with some items + // If the global offset has not changed but you've run out of items to consume, move over from your current position until you find an producer with something in it + + if (token.desiredProducer == nullptr || token.lastKnownGlobalOffset != globalExplicitConsumerOffset.load(std::memory_order_relaxed)) { + if (!update_current_producer_after_rotation(token)) { + return false; + } + } + + // If there was at least one non-empty queue but it appears empty at the time + // we try to dequeue from it, we need to make sure every queue's been tried + if (static_cast<ProducerBase*>(token.currentProducer)->dequeue(item)) { + if (++token.itemsConsumedFromCurrent == EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE) { + globalExplicitConsumerOffset.fetch_add(1, std::memory_order_relaxed); + } + return true; + } + + auto tail = producerListTail.load(std::memory_order_acquire); + auto ptr = static_cast<ProducerBase*>(token.currentProducer)->next_prod(); + if (ptr == nullptr) { + ptr = tail; + } + while (ptr != static_cast<ProducerBase*>(token.currentProducer)) { + if (ptr->dequeue(item)) { + token.currentProducer = ptr; + token.itemsConsumedFromCurrent = 1; + return true; + } + ptr = ptr->next_prod(); + if (ptr == nullptr) { + ptr = tail; + } + } + return false; + } + + // Attempts to dequeue several elements from the queue. + // Returns the number of items actually dequeued. + // Returns 0 if all producer streams appeared empty at the time they + // were checked (so, the queue is likely but not guaranteed to be empty). + // Never allocates. Thread-safe. + template<typename It> + size_t try_dequeue_bulk(It itemFirst, size_t max) + { + size_t count = 0; + for (auto ptr = producerListTail.load(std::memory_order_acquire); ptr != nullptr; ptr = ptr->next_prod()) { + count += ptr->dequeue_bulk(itemFirst, max - count); + if (count == max) { + break; + } + } + return count; + } + + // Attempts to dequeue several elements from the queue using an explicit consumer token. + // Returns the number of items actually dequeued. + // Returns 0 if all producer streams appeared empty at the time they + // were checked (so, the queue is likely but not guaranteed to be empty). + // Never allocates. Thread-safe. + template<typename It> + size_t try_dequeue_bulk(consumer_token_t& token, It itemFirst, size_t max) + { + if (token.desiredProducer == nullptr || token.lastKnownGlobalOffset != globalExplicitConsumerOffset.load(std::memory_order_relaxed)) { + if (!update_current_producer_after_rotation(token)) { + return 0; + } + } + + size_t count = static_cast<ProducerBase*>(token.currentProducer)->dequeue_bulk(itemFirst, max); + if (count == max) { + if ((token.itemsConsumedFromCurrent += static_cast<std::uint32_t>(max)) >= EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE) { + globalExplicitConsumerOffset.fetch_add(1, std::memory_order_relaxed); + } + return max; + } + token.itemsConsumedFromCurrent += static_cast<std::uint32_t>(count); + max -= count; + + auto tail = producerListTail.load(std::memory_order_acquire); + auto ptr = static_cast<ProducerBase*>(token.currentProducer)->next_prod(); + if (ptr == nullptr) { + ptr = tail; + } + while (ptr != static_cast<ProducerBase*>(token.currentProducer)) { + auto dequeued = ptr->dequeue_bulk(itemFirst, max); + count += dequeued; + if (dequeued != 0) { + token.currentProducer = ptr; + token.itemsConsumedFromCurrent = static_cast<std::uint32_t>(dequeued); + } + if (dequeued == max) { + break; + } + max -= dequeued; + ptr = ptr->next_prod(); + if (ptr == nullptr) { + ptr = tail; + } + } + return count; + } + + + + // Attempts to dequeue from a specific producer's inner queue. + // If you happen to know which producer you want to dequeue from, this + // is significantly faster than using the general-case try_dequeue methods. + // Returns false if the producer's queue appeared empty at the time it + // was checked (so, the queue is likely but not guaranteed to be empty). + // Never allocates. Thread-safe. + template<typename U> + inline bool try_dequeue_from_producer(producer_token_t const& producer, U& item) + { + return static_cast<ExplicitProducer*>(producer.producer)->dequeue(item); + } + + // Attempts to dequeue several elements from a specific producer's inner queue. + // Returns the number of items actually dequeued. + // If you happen to know which producer you want to dequeue from, this + // is significantly faster than using the general-case try_dequeue methods. + // Returns 0 if the producer's queue appeared empty at the time it + // was checked (so, the queue is likely but not guaranteed to be empty). + // Never allocates. Thread-safe. + template<typename It> + inline size_t try_dequeue_bulk_from_producer(producer_token_t const& producer, It itemFirst, size_t max) + { + return static_cast<ExplicitProducer*>(producer.producer)->dequeue_bulk(itemFirst, max); + } + + + // Returns an estimate of the total number of elements currently in the queue. This + // estimate is only accurate if the queue has completely stabilized before it is called + // (i.e. all enqueue and dequeue operations have completed and their memory effects are + // visible on the calling thread, and no further operations start while this method is + // being called). + // Thread-safe. + size_t size_approx() const + { + size_t size = 0; + for (auto ptr = producerListTail.load(std::memory_order_acquire); ptr != nullptr; ptr = ptr->next_prod()) { + size += ptr->size_approx(); + } + return size; + } + + + // Returns true if the underlying atomic variables used by + // the queue are lock-free (they should be on most platforms). + // Thread-safe. + static constexpr bool is_lock_free() + { + return + details::static_is_lock_free<bool>::value == 2 && + details::static_is_lock_free<size_t>::value == 2 && + details::static_is_lock_free<std::uint32_t>::value == 2 && + details::static_is_lock_free<index_t>::value == 2 && + details::static_is_lock_free<void*>::value == 2 && + details::static_is_lock_free<typename details::thread_id_converter<details::thread_id_t>::thread_id_numeric_size_t>::value == 2; + } + + +private: + friend struct ProducerToken; + friend struct ConsumerToken; + struct ExplicitProducer; + friend struct ExplicitProducer; + struct ImplicitProducer; + friend struct ImplicitProducer; + friend class ConcurrentQueueTests; + + enum AllocationMode { CanAlloc, CannotAlloc }; + + + /////////////////////////////// + // Queue methods + /////////////////////////////// + + template<AllocationMode canAlloc, typename U> + inline bool inner_enqueue(producer_token_t const& token, U&& element) + { + return static_cast<ExplicitProducer*>(token.producer)->ConcurrentQueue::ExplicitProducer::template enqueue<canAlloc>(std::forward<U>(element)); + } + + template<AllocationMode canAlloc, typename U> + inline bool inner_enqueue(U&& element) + { + auto producer = get_or_add_implicit_producer(); + return producer == nullptr ? false : producer->ConcurrentQueue::ImplicitProducer::template enqueue<canAlloc>(std::forward<U>(element)); + } + + template<AllocationMode canAlloc, typename It> + inline bool inner_enqueue_bulk(producer_token_t const& token, It itemFirst, size_t count) + { + return static_cast<ExplicitProducer*>(token.producer)->ConcurrentQueue::ExplicitProducer::template enqueue_bulk<canAlloc>(itemFirst, count); + } + + template<AllocationMode canAlloc, typename It> + inline bool inner_enqueue_bulk(It itemFirst, size_t count) + { + auto producer = get_or_add_implicit_producer(); + return producer == nullptr ? false : producer->ConcurrentQueue::ImplicitProducer::template enqueue_bulk<canAlloc>(itemFirst, count); + } + + inline bool update_current_producer_after_rotation(consumer_token_t& token) + { + // Ah, there's been a rotation, figure out where we should be! + auto tail = producerListTail.load(std::memory_order_acquire); + if (token.desiredProducer == nullptr && tail == nullptr) { + return false; + } + auto prodCount = producerCount.load(std::memory_order_relaxed); + auto globalOffset = globalExplicitConsumerOffset.load(std::memory_order_relaxed); + if ((details::unlikely)(token.desiredProducer == nullptr)) { + // Aha, first time we're dequeueing anything. + // Figure out our local position + // Note: offset is from start, not end, but we're traversing from end -- subtract from count first + std::uint32_t offset = prodCount - 1 - (token.initialOffset % prodCount); + token.desiredProducer = tail; + for (std::uint32_t i = 0; i != offset; ++i) { + token.desiredProducer = static_cast<ProducerBase*>(token.desiredProducer)->next_prod(); + if (token.desiredProducer == nullptr) { + token.desiredProducer = tail; + } + } + } + + std::uint32_t delta = globalOffset - token.lastKnownGlobalOffset; + if (delta >= prodCount) { + delta = delta % prodCount; + } + for (std::uint32_t i = 0; i != delta; ++i) { + token.desiredProducer = static_cast<ProducerBase*>(token.desiredProducer)->next_prod(); + if (token.desiredProducer == nullptr) { + token.desiredProducer = tail; + } + } + + token.lastKnownGlobalOffset = globalOffset; + token.currentProducer = token.desiredProducer; + token.itemsConsumedFromCurrent = 0; + return true; + } + + + /////////////////////////// + // Free list + /////////////////////////// + + template <typename N> + struct FreeListNode + { + FreeListNode() : freeListRefs(0), freeListNext(nullptr) { } + + std::atomic<std::uint32_t> freeListRefs; + std::atomic<N*> freeListNext; + }; + + // A simple CAS-based lock-free free list. Not the fastest thing in the world under heavy contention, but + // simple and correct (assuming nodes are never freed until after the free list is destroyed), and fairly + // speedy under low contention. + template<typename N> // N must inherit FreeListNode or have the same fields (and initialization of them) + struct FreeList + { + FreeList() : freeListHead(nullptr) { } + FreeList(FreeList&& other) : freeListHead(other.freeListHead.load(std::memory_order_relaxed)) { other.freeListHead.store(nullptr, std::memory_order_relaxed); } + void swap(FreeList& other) { details::swap_relaxed(freeListHead, other.freeListHead); } + + FreeList(FreeList const&) MOODYCAMEL_DELETE_FUNCTION; + FreeList& operator=(FreeList const&) MOODYCAMEL_DELETE_FUNCTION; + + inline void add(N* node) + { +#ifdef MCDBGQ_NOLOCKFREE_FREELIST + debug::DebugLock lock(mutex); +#endif + // We know that the should-be-on-freelist bit is 0 at this point, so it's safe to + // set it using a fetch_add + if (node->freeListRefs.fetch_add(SHOULD_BE_ON_FREELIST, std::memory_order_acq_rel) == 0) { + // Oh look! We were the last ones referencing this node, and we know + // we want to add it to the free list, so let's do it! + add_knowing_refcount_is_zero(node); + } + } + + inline N* try_get() + { +#ifdef MCDBGQ_NOLOCKFREE_FREELIST + debug::DebugLock lock(mutex); +#endif + auto head = freeListHead.load(std::memory_order_acquire); + while (head != nullptr) { + auto prevHead = head; + auto refs = head->freeListRefs.load(std::memory_order_relaxed); + if ((refs & REFS_MASK) == 0 || !head->freeListRefs.compare_exchange_strong(refs, refs + 1, std::memory_order_acquire)) { + head = freeListHead.load(std::memory_order_acquire); + continue; + } + + // Good, reference count has been incremented (it wasn't at zero), which means we can read the + // next and not worry about it changing between now and the time we do the CAS + auto next = head->freeListNext.load(std::memory_order_relaxed); + if (freeListHead.compare_exchange_strong(head, next, std::memory_order_acquire, std::memory_order_relaxed)) { + // Yay, got the node. This means it was on the list, which means shouldBeOnFreeList must be false no + // matter the refcount (because nobody else knows it's been taken off yet, it can't have been put back on). + assert((head->freeListRefs.load(std::memory_order_relaxed) & SHOULD_BE_ON_FREELIST) == 0); + + // Decrease refcount twice, once for our ref, and once for the list's ref + head->freeListRefs.fetch_sub(2, std::memory_order_release); + return head; + } + + // OK, the head must have changed on us, but we still need to decrease the refcount we increased. + // Note that we don't need to release any memory effects, but we do need to ensure that the reference + // count decrement happens-after the CAS on the head. + refs = prevHead->freeListRefs.fetch_sub(1, std::memory_order_acq_rel); + if (refs == SHOULD_BE_ON_FREELIST + 1) { + add_knowing_refcount_is_zero(prevHead); + } + } + + return nullptr; + } + + // Useful for traversing the list when there's no contention (e.g. to destroy remaining nodes) + N* head_unsafe() const { return freeListHead.load(std::memory_order_relaxed); } + + private: + inline void add_knowing_refcount_is_zero(N* node) + { + // Since the refcount is zero, and nobody can increase it once it's zero (except us, and we run + // only one copy of this method per node at a time, i.e. the single thread case), then we know + // we can safely change the next pointer of the node; however, once the refcount is back above + // zero, then other threads could increase it (happens under heavy contention, when the refcount + // goes to zero in between a load and a refcount increment of a node in try_get, then back up to + // something non-zero, then the refcount increment is done by the other thread) -- so, if the CAS + // to add the node to the actual list fails, decrease the refcount and leave the add operation to + // the next thread who puts the refcount back at zero (which could be us, hence the loop). + auto head = freeListHead.load(std::memory_order_relaxed); + while (true) { + node->freeListNext.store(head, std::memory_order_relaxed); + node->freeListRefs.store(1, std::memory_order_release); + if (!freeListHead.compare_exchange_strong(head, node, std::memory_order_release, std::memory_order_relaxed)) { + // Hmm, the add failed, but we can only try again when the refcount goes back to zero + if (node->freeListRefs.fetch_add(SHOULD_BE_ON_FREELIST - 1, std::memory_order_acq_rel) == 1) { + continue; + } + } + return; + } + } + + private: + // Implemented like a stack, but where node order doesn't matter (nodes are inserted out of order under contention) + std::atomic<N*> freeListHead; + + static const std::uint32_t REFS_MASK = 0x7FFFFFFF; + static const std::uint32_t SHOULD_BE_ON_FREELIST = 0x80000000; + +#ifdef MCDBGQ_NOLOCKFREE_FREELIST + debug::DebugMutex mutex; +#endif + }; + + + /////////////////////////// + // Block + /////////////////////////// + + enum InnerQueueContext { implicit_context = 0, explicit_context = 1 }; + + struct Block + { + Block() + : next(nullptr), elementsCompletelyDequeued(0), freeListRefs(0), freeListNext(nullptr), dynamicallyAllocated(true) + { +#ifdef MCDBGQ_TRACKMEM + owner = nullptr; +#endif + } + + template<InnerQueueContext context> + inline bool is_empty() const + { + MOODYCAMEL_CONSTEXPR_IF (context == explicit_context && BLOCK_SIZE <= EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD) { + // Check flags + for (size_t i = 0; i < BLOCK_SIZE; ++i) { + if (!emptyFlags[i].load(std::memory_order_relaxed)) { + return false; + } + } + + // Aha, empty; make sure we have all other memory effects that happened before the empty flags were set + std::atomic_thread_fence(std::memory_order_acquire); + return true; + } + else { + // Check counter + if (elementsCompletelyDequeued.load(std::memory_order_relaxed) == BLOCK_SIZE) { + std::atomic_thread_fence(std::memory_order_acquire); + return true; + } + assert(elementsCompletelyDequeued.load(std::memory_order_relaxed) <= BLOCK_SIZE); + return false; + } + } + + // Returns true if the block is now empty (does not apply in explicit context) + template<InnerQueueContext context> + inline bool set_empty(MOODYCAMEL_MAYBE_UNUSED index_t i) + { + MOODYCAMEL_CONSTEXPR_IF (context == explicit_context && BLOCK_SIZE <= EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD) { + // Set flag + assert(!emptyFlags[BLOCK_SIZE - 1 - static_cast<size_t>(i & static_cast<index_t>(BLOCK_SIZE - 1))].load(std::memory_order_relaxed)); + emptyFlags[BLOCK_SIZE - 1 - static_cast<size_t>(i & static_cast<index_t>(BLOCK_SIZE - 1))].store(true, std::memory_order_release); + return false; + } + else { + // Increment counter + auto prevVal = elementsCompletelyDequeued.fetch_add(1, std::memory_order_acq_rel); + assert(prevVal < BLOCK_SIZE); + return prevVal == BLOCK_SIZE - 1; + } + } + + // Sets multiple contiguous item statuses to 'empty' (assumes no wrapping and count > 0). + // Returns true if the block is now empty (does not apply in explicit context). + template<InnerQueueContext context> + inline bool set_many_empty(MOODYCAMEL_MAYBE_UNUSED index_t i, size_t count) + { + MOODYCAMEL_CONSTEXPR_IF (context == explicit_context && BLOCK_SIZE <= EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD) { + // Set flags + std::atomic_thread_fence(std::memory_order_release); + i = BLOCK_SIZE - 1 - static_cast<size_t>(i & static_cast<index_t>(BLOCK_SIZE - 1)) - count + 1; + for (size_t j = 0; j != count; ++j) { + assert(!emptyFlags[i + j].load(std::memory_order_relaxed)); + emptyFlags[i + j].store(true, std::memory_order_relaxed); + } + return false; + } + else { + // Increment counter + auto prevVal = elementsCompletelyDequeued.fetch_add(count, std::memory_order_acq_rel); + assert(prevVal + count <= BLOCK_SIZE); + return prevVal + count == BLOCK_SIZE; + } + } + + template<InnerQueueContext context> + inline void set_all_empty() + { + MOODYCAMEL_CONSTEXPR_IF (context == explicit_context && BLOCK_SIZE <= EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD) { + // Set all flags + for (size_t i = 0; i != BLOCK_SIZE; ++i) { + emptyFlags[i].store(true, std::memory_order_relaxed); + } + } + else { + // Reset counter + elementsCompletelyDequeued.store(BLOCK_SIZE, std::memory_order_relaxed); + } + } + + template<InnerQueueContext context> + inline void reset_empty() + { + MOODYCAMEL_CONSTEXPR_IF (context == explicit_context && BLOCK_SIZE <= EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD) { + // Reset flags + for (size_t i = 0; i != BLOCK_SIZE; ++i) { + emptyFlags[i].store(false, std::memory_order_relaxed); + } + } + else { + // Reset counter + elementsCompletelyDequeued.store(0, std::memory_order_relaxed); + } + } + + inline T* operator[](index_t idx) MOODYCAMEL_NOEXCEPT { return static_cast<T*>(static_cast<void*>(elements)) + static_cast<size_t>(idx & static_cast<index_t>(BLOCK_SIZE - 1)); } + inline T const* operator[](index_t idx) const MOODYCAMEL_NOEXCEPT { return static_cast<T const*>(static_cast<void const*>(elements)) + static_cast<size_t>(idx & static_cast<index_t>(BLOCK_SIZE - 1)); } + + private: + static_assert(std::alignment_of<T>::value <= sizeof(T), "The queue does not support types with an alignment greater than their size at this time"); + MOODYCAMEL_ALIGNED_TYPE_LIKE(char[sizeof(T) * BLOCK_SIZE], T) elements; + public: + Block* next; + std::atomic<size_t> elementsCompletelyDequeued; + std::atomic<bool> emptyFlags[BLOCK_SIZE <= EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD ? BLOCK_SIZE : 1]; + public: + std::atomic<std::uint32_t> freeListRefs; + std::atomic<Block*> freeListNext; + bool dynamicallyAllocated; // Perhaps a better name for this would be 'isNotPartOfInitialBlockPool' + +#ifdef MCDBGQ_TRACKMEM + void* owner; +#endif + }; + static_assert(std::alignment_of<Block>::value >= std::alignment_of<T>::value, "Internal error: Blocks must be at least as aligned as the type they are wrapping"); + + +#ifdef MCDBGQ_TRACKMEM +public: + struct MemStats; +private: +#endif + + /////////////////////////// + // Producer base + /////////////////////////// + + struct ProducerBase : public details::ConcurrentQueueProducerTypelessBase + { + ProducerBase(ConcurrentQueue* parent_, bool isExplicit_) : + tailIndex(0), + headIndex(0), + dequeueOptimisticCount(0), + dequeueOvercommit(0), + tailBlock(nullptr), + isExplicit(isExplicit_), + parent(parent_) + { + } + + virtual ~ProducerBase() { } + + template<typename U> + inline bool dequeue(U& element) + { + if (isExplicit) { + return static_cast<ExplicitProducer*>(this)->dequeue(element); + } + else { + return static_cast<ImplicitProducer*>(this)->dequeue(element); + } + } + + template<typename It> + inline size_t dequeue_bulk(It& itemFirst, size_t max) + { + if (isExplicit) { + return static_cast<ExplicitProducer*>(this)->dequeue_bulk(itemFirst, max); + } + else { + return static_cast<ImplicitProducer*>(this)->dequeue_bulk(itemFirst, max); + } + } + + inline ProducerBase* next_prod() const { return static_cast<ProducerBase*>(next); } + + inline size_t size_approx() const + { + auto tail = tailIndex.load(std::memory_order_relaxed); + auto head = headIndex.load(std::memory_order_relaxed); + return details::circular_less_than(head, tail) ? static_cast<size_t>(tail - head) : 0; + } + + inline index_t getTail() const { return tailIndex.load(std::memory_order_relaxed); } + protected: + std::atomic<index_t> tailIndex; // Where to enqueue to next + std::atomic<index_t> headIndex; // Where to dequeue from next + + std::atomic<index_t> dequeueOptimisticCount; + std::atomic<index_t> dequeueOvercommit; + + Block* tailBlock; + + public: + bool isExplicit; + ConcurrentQueue* parent; + + protected: +#ifdef MCDBGQ_TRACKMEM + friend struct MemStats; +#endif + }; + + + /////////////////////////// + // Explicit queue + /////////////////////////// + + struct ExplicitProducer : public ProducerBase + { + explicit ExplicitProducer(ConcurrentQueue* parent_) : + ProducerBase(parent_, true), + blockIndex(nullptr), + pr_blockIndexSlotsUsed(0), + pr_blockIndexSize(EXPLICIT_INITIAL_INDEX_SIZE >> 1), + pr_blockIndexFront(0), + pr_blockIndexEntries(nullptr), + pr_blockIndexRaw(nullptr) + { + size_t poolBasedIndexSize = details::ceil_to_pow_2(parent_->initialBlockPoolSize) >> 1; + if (poolBasedIndexSize > pr_blockIndexSize) { + pr_blockIndexSize = poolBasedIndexSize; + } + + new_block_index(0); // This creates an index with double the number of current entries, i.e. EXPLICIT_INITIAL_INDEX_SIZE + } + + ~ExplicitProducer() + { + // Destruct any elements not yet dequeued. + // Since we're in the destructor, we can assume all elements + // are either completely dequeued or completely not (no halfways). + if (this->tailBlock != nullptr) { // Note this means there must be a block index too + // First find the block that's partially dequeued, if any + Block* halfDequeuedBlock = nullptr; + if ((this->headIndex.load(std::memory_order_relaxed) & static_cast<index_t>(BLOCK_SIZE - 1)) != 0) { + // The head's not on a block boundary, meaning a block somewhere is partially dequeued + // (or the head block is the tail block and was fully dequeued, but the head/tail are still not on a boundary) + size_t i = (pr_blockIndexFront - pr_blockIndexSlotsUsed) & (pr_blockIndexSize - 1); + while (details::circular_less_than<index_t>(pr_blockIndexEntries[i].base + BLOCK_SIZE, this->headIndex.load(std::memory_order_relaxed))) { + i = (i + 1) & (pr_blockIndexSize - 1); + } + assert(details::circular_less_than<index_t>(pr_blockIndexEntries[i].base, this->headIndex.load(std::memory_order_relaxed))); + halfDequeuedBlock = pr_blockIndexEntries[i].block; + } + + // Start at the head block (note the first line in the loop gives us the head from the tail on the first iteration) + auto block = this->tailBlock; + do { + block = block->next; + if (block->ConcurrentQueue::Block::template is_empty<explicit_context>()) { + continue; + } + + size_t i = 0; // Offset into block + if (block == halfDequeuedBlock) { + i = static_cast<size_t>(this->headIndex.load(std::memory_order_relaxed) & static_cast<index_t>(BLOCK_SIZE - 1)); + } + + // Walk through all the items in the block; if this is the tail block, we need to stop when we reach the tail index + auto lastValidIndex = (this->tailIndex.load(std::memory_order_relaxed) & static_cast<index_t>(BLOCK_SIZE - 1)) == 0 ? BLOCK_SIZE : static_cast<size_t>(this->tailIndex.load(std::memory_order_relaxed) & static_cast<index_t>(BLOCK_SIZE - 1)); + while (i != BLOCK_SIZE && (block != this->tailBlock || i != lastValidIndex)) { + (*block)[i++]->~T(); + } + } while (block != this->tailBlock); + } + + // Destroy all blocks that we own + if (this->tailBlock != nullptr) { + auto block = this->tailBlock; + do { + auto nextBlock = block->next; + this->parent->add_block_to_free_list(block); + block = nextBlock; + } while (block != this->tailBlock); + } + + // Destroy the block indices + auto header = static_cast<BlockIndexHeader*>(pr_blockIndexRaw); + while (header != nullptr) { + auto prev = static_cast<BlockIndexHeader*>(header->prev); + header->~BlockIndexHeader(); + (Traits::free)(header); + header = prev; + } + } + + template<AllocationMode allocMode, typename U> + inline bool enqueue(U&& element) + { + index_t currentTailIndex = this->tailIndex.load(std::memory_order_relaxed); + index_t newTailIndex = 1 + currentTailIndex; + if ((currentTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) == 0) { + // We reached the end of a block, start a new one + auto startBlock = this->tailBlock; + auto originalBlockIndexSlotsUsed = pr_blockIndexSlotsUsed; + if (this->tailBlock != nullptr && this->tailBlock->next->ConcurrentQueue::Block::template is_empty<explicit_context>()) { + // We can re-use the block ahead of us, it's empty! + this->tailBlock = this->tailBlock->next; + this->tailBlock->ConcurrentQueue::Block::template reset_empty<explicit_context>(); + + // We'll put the block on the block index (guaranteed to be room since we're conceptually removing the + // last block from it first -- except instead of removing then adding, we can just overwrite). + // Note that there must be a valid block index here, since even if allocation failed in the ctor, + // it would have been re-attempted when adding the first block to the queue; since there is such + // a block, a block index must have been successfully allocated. + } + else { + // Whatever head value we see here is >= the last value we saw here (relatively), + // and <= its current value. Since we have the most recent tail, the head must be + // <= to it. + auto head = this->headIndex.load(std::memory_order_relaxed); + assert(!details::circular_less_than<index_t>(currentTailIndex, head)); + if (!details::circular_less_than<index_t>(head, currentTailIndex + BLOCK_SIZE) + || (MAX_SUBQUEUE_SIZE != details::const_numeric_max<size_t>::value && (MAX_SUBQUEUE_SIZE == 0 || MAX_SUBQUEUE_SIZE - BLOCK_SIZE < currentTailIndex - head))) { + // We can't enqueue in another block because there's not enough leeway -- the + // tail could surpass the head by the time the block fills up! (Or we'll exceed + // the size limit, if the second part of the condition was true.) + return false; + } + // We're going to need a new block; check that the block index has room + if (pr_blockIndexRaw == nullptr || pr_blockIndexSlotsUsed == pr_blockIndexSize) { + // Hmm, the circular block index is already full -- we'll need + // to allocate a new index. Note pr_blockIndexRaw can only be nullptr if + // the initial allocation failed in the constructor. + + MOODYCAMEL_CONSTEXPR_IF (allocMode == CannotAlloc) { + return false; + } + else if (!new_block_index(pr_blockIndexSlotsUsed)) { + return false; + } + } + + // Insert a new block in the circular linked list + auto newBlock = this->parent->ConcurrentQueue::template requisition_block<allocMode>(); + if (newBlock == nullptr) { + return false; + } +#ifdef MCDBGQ_TRACKMEM + newBlock->owner = this; +#endif + newBlock->ConcurrentQueue::Block::template reset_empty<explicit_context>(); + if (this->tailBlock == nullptr) { + newBlock->next = newBlock; + } + else { + newBlock->next = this->tailBlock->next; + this->tailBlock->next = newBlock; + } + this->tailBlock = newBlock; + ++pr_blockIndexSlotsUsed; + } + + MOODYCAMEL_CONSTEXPR_IF (!MOODYCAMEL_NOEXCEPT_CTOR(T, U, new (static_cast<T*>(nullptr)) T(std::forward<U>(element)))) { + // The constructor may throw. We want the element not to appear in the queue in + // that case (without corrupting the queue): + MOODYCAMEL_TRY { + new ((*this->tailBlock)[currentTailIndex]) T(std::forward<U>(element)); + } + MOODYCAMEL_CATCH (...) { + // Revert change to the current block, but leave the new block available + // for next time + pr_blockIndexSlotsUsed = originalBlockIndexSlotsUsed; + this->tailBlock = startBlock == nullptr ? this->tailBlock : startBlock; + MOODYCAMEL_RETHROW; + } + } + else { + (void)startBlock; + (void)originalBlockIndexSlotsUsed; + } + + // Add block to block index + auto& entry = blockIndex.load(std::memory_order_relaxed)->entries[pr_blockIndexFront]; + entry.base = currentTailIndex; + entry.block = this->tailBlock; + blockIndex.load(std::memory_order_relaxed)->front.store(pr_blockIndexFront, std::memory_order_release); + pr_blockIndexFront = (pr_blockIndexFront + 1) & (pr_blockIndexSize - 1); + + MOODYCAMEL_CONSTEXPR_IF (!MOODYCAMEL_NOEXCEPT_CTOR(T, U, new (static_cast<T*>(nullptr)) T(std::forward<U>(element)))) { + this->tailIndex.store(newTailIndex, std::memory_order_release); + return true; + } + } + + // Enqueue + new ((*this->tailBlock)[currentTailIndex]) T(std::forward<U>(element)); + + this->tailIndex.store(newTailIndex, std::memory_order_release); + return true; + } + + template<typename U> + bool dequeue(U& element) + { + auto tail = this->tailIndex.load(std::memory_order_relaxed); + auto overcommit = this->dequeueOvercommit.load(std::memory_order_relaxed); + if (details::circular_less_than<index_t>(this->dequeueOptimisticCount.load(std::memory_order_relaxed) - overcommit, tail)) { + // Might be something to dequeue, let's give it a try + + // Note that this if is purely for performance purposes in the common case when the queue is + // empty and the values are eventually consistent -- we may enter here spuriously. + + // Note that whatever the values of overcommit and tail are, they are not going to change (unless we + // change them) and must be the same value at this point (inside the if) as when the if condition was + // evaluated. + + // We insert an acquire fence here to synchronize-with the release upon incrementing dequeueOvercommit below. + // This ensures that whatever the value we got loaded into overcommit, the load of dequeueOptisticCount in + // the fetch_add below will result in a value at least as recent as that (and therefore at least as large). + // Note that I believe a compiler (signal) fence here would be sufficient due to the nature of fetch_add (all + // read-modify-write operations are guaranteed to work on the latest value in the modification order), but + // unfortunately that can't be shown to be correct using only the C++11 standard. + // See http://stackoverflow.com/questions/18223161/what-are-the-c11-memory-ordering-guarantees-in-this-corner-case + std::atomic_thread_fence(std::memory_order_acquire); + + // Increment optimistic counter, then check if it went over the boundary + auto myDequeueCount = this->dequeueOptimisticCount.fetch_add(1, std::memory_order_relaxed); + + // Note that since dequeueOvercommit must be <= dequeueOptimisticCount (because dequeueOvercommit is only ever + // incremented after dequeueOptimisticCount -- this is enforced in the `else` block below), and since we now + // have a version of dequeueOptimisticCount that is at least as recent as overcommit (due to the release upon + // incrementing dequeueOvercommit and the acquire above that synchronizes with it), overcommit <= myDequeueCount. + // However, we can't assert this since both dequeueOptimisticCount and dequeueOvercommit may (independently) + // overflow; in such a case, though, the logic still holds since the difference between the two is maintained. + + // Note that we reload tail here in case it changed; it will be the same value as before or greater, since + // this load is sequenced after (happens after) the earlier load above. This is supported by read-read + // coherency (as defined in the standard), explained here: http://en.cppreference.com/w/cpp/atomic/memory_order + tail = this->tailIndex.load(std::memory_order_acquire); + if ((details::likely)(details::circular_less_than<index_t>(myDequeueCount - overcommit, tail))) { + // Guaranteed to be at least one element to dequeue! + + // Get the index. Note that since there's guaranteed to be at least one element, this + // will never exceed tail. We need to do an acquire-release fence here since it's possible + // that whatever condition got us to this point was for an earlier enqueued element (that + // we already see the memory effects for), but that by the time we increment somebody else + // has incremented it, and we need to see the memory effects for *that* element, which is + // in such a case is necessarily visible on the thread that incremented it in the first + // place with the more current condition (they must have acquired a tail that is at least + // as recent). + auto index = this->headIndex.fetch_add(1, std::memory_order_acq_rel); + + + // Determine which block the element is in + + auto localBlockIndex = blockIndex.load(std::memory_order_acquire); + auto localBlockIndexHead = localBlockIndex->front.load(std::memory_order_acquire); + + // We need to be careful here about subtracting and dividing because of index wrap-around. + // When an index wraps, we need to preserve the sign of the offset when dividing it by the + // block size (in order to get a correct signed block count offset in all cases): + auto headBase = localBlockIndex->entries[localBlockIndexHead].base; + auto blockBaseIndex = index & ~static_cast<index_t>(BLOCK_SIZE - 1); + auto offset = static_cast<size_t>(static_cast<typename std::make_signed<index_t>::type>(blockBaseIndex - headBase) / static_cast<typename std::make_signed<index_t>::type>(BLOCK_SIZE)); + auto block = localBlockIndex->entries[(localBlockIndexHead + offset) & (localBlockIndex->size - 1)].block; + + // Dequeue + auto& el = *((*block)[index]); + if (!MOODYCAMEL_NOEXCEPT_ASSIGN(T, T&&, element = std::move(el))) { + // Make sure the element is still fully dequeued and destroyed even if the assignment + // throws + struct Guard { + Block* block; + index_t index; + + ~Guard() + { + (*block)[index]->~T(); + block->ConcurrentQueue::Block::template set_empty<explicit_context>(index); + } + } guard = { block, index }; + + element = std::move(el); // NOLINT + } + else { + element = std::move(el); // NOLINT + el.~T(); // NOLINT + block->ConcurrentQueue::Block::template set_empty<explicit_context>(index); + } + + return true; + } + else { + // Wasn't anything to dequeue after all; make the effective dequeue count eventually consistent + this->dequeueOvercommit.fetch_add(1, std::memory_order_release); // Release so that the fetch_add on dequeueOptimisticCount is guaranteed to happen before this write + } + } + + return false; + } + + template<AllocationMode allocMode, typename It> + bool MOODYCAMEL_NO_TSAN enqueue_bulk(It itemFirst, size_t count) + { + // First, we need to make sure we have enough room to enqueue all of the elements; + // this means pre-allocating blocks and putting them in the block index (but only if + // all the allocations succeeded). + index_t startTailIndex = this->tailIndex.load(std::memory_order_relaxed); + auto startBlock = this->tailBlock; + auto originalBlockIndexFront = pr_blockIndexFront; + auto originalBlockIndexSlotsUsed = pr_blockIndexSlotsUsed; + + Block* firstAllocatedBlock = nullptr; + + // Figure out how many blocks we'll need to allocate, and do so + size_t blockBaseDiff = ((startTailIndex + count - 1) & ~static_cast<index_t>(BLOCK_SIZE - 1)) - ((startTailIndex - 1) & ~static_cast<index_t>(BLOCK_SIZE - 1)); + index_t currentTailIndex = (startTailIndex - 1) & ~static_cast<index_t>(BLOCK_SIZE - 1); + if (blockBaseDiff > 0) { + // Allocate as many blocks as possible from ahead + while (blockBaseDiff > 0 && this->tailBlock != nullptr && this->tailBlock->next != firstAllocatedBlock && this->tailBlock->next->ConcurrentQueue::Block::template is_empty<explicit_context>()) { + blockBaseDiff -= static_cast<index_t>(BLOCK_SIZE); + currentTailIndex += static_cast<index_t>(BLOCK_SIZE); + + this->tailBlock = this->tailBlock->next; + firstAllocatedBlock = firstAllocatedBlock == nullptr ? this->tailBlock : firstAllocatedBlock; + + auto& entry = blockIndex.load(std::memory_order_relaxed)->entries[pr_blockIndexFront]; + entry.base = currentTailIndex; + entry.block = this->tailBlock; + pr_blockIndexFront = (pr_blockIndexFront + 1) & (pr_blockIndexSize - 1); + } + + // Now allocate as many blocks as necessary from the block pool + while (blockBaseDiff > 0) { + blockBaseDiff -= static_cast<index_t>(BLOCK_SIZE); + currentTailIndex += static_cast<index_t>(BLOCK_SIZE); + + auto head = this->headIndex.load(std::memory_order_relaxed); + assert(!details::circular_less_than<index_t>(currentTailIndex, head)); + bool full = !details::circular_less_than<index_t>(head, currentTailIndex + BLOCK_SIZE) || (MAX_SUBQUEUE_SIZE != details::const_numeric_max<size_t>::value && (MAX_SUBQUEUE_SIZE == 0 || MAX_SUBQUEUE_SIZE - BLOCK_SIZE < currentTailIndex - head)); + if (pr_blockIndexRaw == nullptr || pr_blockIndexSlotsUsed == pr_blockIndexSize || full) { + MOODYCAMEL_CONSTEXPR_IF (allocMode == CannotAlloc) { + // Failed to allocate, undo changes (but keep injected blocks) + pr_blockIndexFront = originalBlockIndexFront; + pr_blockIndexSlotsUsed = originalBlockIndexSlotsUsed; + this->tailBlock = startBlock == nullptr ? firstAllocatedBlock : startBlock; + return false; + } + else if (full || !new_block_index(originalBlockIndexSlotsUsed)) { + // Failed to allocate, undo changes (but keep injected blocks) + pr_blockIndexFront = originalBlockIndexFront; + pr_blockIndexSlotsUsed = originalBlockIndexSlotsUsed; + this->tailBlock = startBlock == nullptr ? firstAllocatedBlock : startBlock; + return false; + } + + // pr_blockIndexFront is updated inside new_block_index, so we need to + // update our fallback value too (since we keep the new index even if we + // later fail) + originalBlockIndexFront = originalBlockIndexSlotsUsed; + } + + // Insert a new block in the circular linked list + auto newBlock = this->parent->ConcurrentQueue::template requisition_block<allocMode>(); + if (newBlock == nullptr) { + pr_blockIndexFront = originalBlockIndexFront; + pr_blockIndexSlotsUsed = originalBlockIndexSlotsUsed; + this->tailBlock = startBlock == nullptr ? firstAllocatedBlock : startBlock; + return false; + } + +#ifdef MCDBGQ_TRACKMEM + newBlock->owner = this; +#endif + newBlock->ConcurrentQueue::Block::template set_all_empty<explicit_context>(); + if (this->tailBlock == nullptr) { + newBlock->next = newBlock; + } + else { + newBlock->next = this->tailBlock->next; + this->tailBlock->next = newBlock; + } + this->tailBlock = newBlock; + firstAllocatedBlock = firstAllocatedBlock == nullptr ? this->tailBlock : firstAllocatedBlock; + + ++pr_blockIndexSlotsUsed; + + auto& entry = blockIndex.load(std::memory_order_relaxed)->entries[pr_blockIndexFront]; + entry.base = currentTailIndex; + entry.block = this->tailBlock; + pr_blockIndexFront = (pr_blockIndexFront + 1) & (pr_blockIndexSize - 1); + } + + // Excellent, all allocations succeeded. Reset each block's emptiness before we fill them up, and + // publish the new block index front + auto block = firstAllocatedBlock; + while (true) { + block->ConcurrentQueue::Block::template reset_empty<explicit_context>(); + if (block == this->tailBlock) { + break; + } + block = block->next; + } + + MOODYCAMEL_CONSTEXPR_IF (MOODYCAMEL_NOEXCEPT_CTOR(T, decltype(*itemFirst), new (static_cast<T*>(nullptr)) T(details::deref_noexcept(itemFirst)))) { + blockIndex.load(std::memory_order_relaxed)->front.store((pr_blockIndexFront - 1) & (pr_blockIndexSize - 1), std::memory_order_release); + } + } + + // Enqueue, one block at a time + index_t newTailIndex = startTailIndex + static_cast<index_t>(count); + currentTailIndex = startTailIndex; + auto endBlock = this->tailBlock; + this->tailBlock = startBlock; + assert((startTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) != 0 || firstAllocatedBlock != nullptr || count == 0); + if ((startTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) == 0 && firstAllocatedBlock != nullptr) { + this->tailBlock = firstAllocatedBlock; + } + while (true) { + index_t stopIndex = (currentTailIndex & ~static_cast<index_t>(BLOCK_SIZE - 1)) + static_cast<index_t>(BLOCK_SIZE); + if (details::circular_less_than<index_t>(newTailIndex, stopIndex)) { + stopIndex = newTailIndex; + } + MOODYCAMEL_CONSTEXPR_IF (MOODYCAMEL_NOEXCEPT_CTOR(T, decltype(*itemFirst), new (static_cast<T*>(nullptr)) T(details::deref_noexcept(itemFirst)))) { + while (currentTailIndex != stopIndex) { + new ((*this->tailBlock)[currentTailIndex++]) T(*itemFirst++); + } + } + else { + MOODYCAMEL_TRY { + while (currentTailIndex != stopIndex) { + // Must use copy constructor even if move constructor is available + // because we may have to revert if there's an exception. + // Sorry about the horrible templated next line, but it was the only way + // to disable moving *at compile time*, which is important because a type + // may only define a (noexcept) move constructor, and so calls to the + // cctor will not compile, even if they are in an if branch that will never + // be executed + new ((*this->tailBlock)[currentTailIndex]) T(details::nomove_if<!MOODYCAMEL_NOEXCEPT_CTOR(T, decltype(*itemFirst), new (static_cast<T*>(nullptr)) T(details::deref_noexcept(itemFirst)))>::eval(*itemFirst)); + ++currentTailIndex; + ++itemFirst; + } + } + MOODYCAMEL_CATCH (...) { + // Oh dear, an exception's been thrown -- destroy the elements that + // were enqueued so far and revert the entire bulk operation (we'll keep + // any allocated blocks in our linked list for later, though). + auto constructedStopIndex = currentTailIndex; + auto lastBlockEnqueued = this->tailBlock; + + pr_blockIndexFront = originalBlockIndexFront; + pr_blockIndexSlotsUsed = originalBlockIndexSlotsUsed; + this->tailBlock = startBlock == nullptr ? firstAllocatedBlock : startBlock; + + if (!details::is_trivially_destructible<T>::value) { + auto block = startBlock; + if ((startTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) == 0) { + block = firstAllocatedBlock; + } + currentTailIndex = startTailIndex; + while (true) { + stopIndex = (currentTailIndex & ~static_cast<index_t>(BLOCK_SIZE - 1)) + static_cast<index_t>(BLOCK_SIZE); + if (details::circular_less_than<index_t>(constructedStopIndex, stopIndex)) { + stopIndex = constructedStopIndex; + } + while (currentTailIndex != stopIndex) { + (*block)[currentTailIndex++]->~T(); + } + if (block == lastBlockEnqueued) { + break; + } + block = block->next; + } + } + MOODYCAMEL_RETHROW; + } + } + + if (this->tailBlock == endBlock) { + assert(currentTailIndex == newTailIndex); + break; + } + this->tailBlock = this->tailBlock->next; + } + + MOODYCAMEL_CONSTEXPR_IF (!MOODYCAMEL_NOEXCEPT_CTOR(T, decltype(*itemFirst), new (static_cast<T*>(nullptr)) T(details::deref_noexcept(itemFirst)))) { + if (firstAllocatedBlock != nullptr) + blockIndex.load(std::memory_order_relaxed)->front.store((pr_blockIndexFront - 1) & (pr_blockIndexSize - 1), std::memory_order_release); + } + + this->tailIndex.store(newTailIndex, std::memory_order_release); + return true; + } + + template<typename It> + size_t dequeue_bulk(It& itemFirst, size_t max) + { + auto tail = this->tailIndex.load(std::memory_order_relaxed); + auto overcommit = this->dequeueOvercommit.load(std::memory_order_relaxed); + auto desiredCount = static_cast<size_t>(tail - (this->dequeueOptimisticCount.load(std::memory_order_relaxed) - overcommit)); + if (details::circular_less_than<size_t>(0, desiredCount)) { + desiredCount = desiredCount < max ? desiredCount : max; + std::atomic_thread_fence(std::memory_order_acquire); + + auto myDequeueCount = this->dequeueOptimisticCount.fetch_add(desiredCount, std::memory_order_relaxed); + + tail = this->tailIndex.load(std::memory_order_acquire); + auto actualCount = static_cast<size_t>(tail - (myDequeueCount - overcommit)); + if (details::circular_less_than<size_t>(0, actualCount)) { + actualCount = desiredCount < actualCount ? desiredCount : actualCount; + if (actualCount < desiredCount) { + this->dequeueOvercommit.fetch_add(desiredCount - actualCount, std::memory_order_release); + } + + // Get the first index. Note that since there's guaranteed to be at least actualCount elements, this + // will never exceed tail. + auto firstIndex = this->headIndex.fetch_add(actualCount, std::memory_order_acq_rel); + + // Determine which block the first element is in + auto localBlockIndex = blockIndex.load(std::memory_order_acquire); + auto localBlockIndexHead = localBlockIndex->front.load(std::memory_order_acquire); + + auto headBase = localBlockIndex->entries[localBlockIndexHead].base; + auto firstBlockBaseIndex = firstIndex & ~static_cast<index_t>(BLOCK_SIZE - 1); + auto offset = static_cast<size_t>(static_cast<typename std::make_signed<index_t>::type>(firstBlockBaseIndex - headBase) / static_cast<typename std::make_signed<index_t>::type>(BLOCK_SIZE)); + auto indexIndex = (localBlockIndexHead + offset) & (localBlockIndex->size - 1); + + // Iterate the blocks and dequeue + auto index = firstIndex; + do { + auto firstIndexInBlock = index; + index_t endIndex = (index & ~static_cast<index_t>(BLOCK_SIZE - 1)) + static_cast<index_t>(BLOCK_SIZE); + endIndex = details::circular_less_than<index_t>(firstIndex + static_cast<index_t>(actualCount), endIndex) ? firstIndex + static_cast<index_t>(actualCount) : endIndex; + auto block = localBlockIndex->entries[indexIndex].block; + if (MOODYCAMEL_NOEXCEPT_ASSIGN(T, T&&, details::deref_noexcept(itemFirst) = std::move((*(*block)[index])))) { + while (index != endIndex) { + auto& el = *((*block)[index]); + *itemFirst++ = std::move(el); + el.~T(); + ++index; + } + } + else { + MOODYCAMEL_TRY { + while (index != endIndex) { + auto& el = *((*block)[index]); + *itemFirst = std::move(el); + ++itemFirst; + el.~T(); + ++index; + } + } + MOODYCAMEL_CATCH (...) { + // It's too late to revert the dequeue, but we can make sure that all + // the dequeued objects are properly destroyed and the block index + // (and empty count) are properly updated before we propagate the exception + do { + block = localBlockIndex->entries[indexIndex].block; + while (index != endIndex) { + (*block)[index++]->~T(); + } + block->ConcurrentQueue::Block::template set_many_empty<explicit_context>(firstIndexInBlock, static_cast<size_t>(endIndex - firstIndexInBlock)); + indexIndex = (indexIndex + 1) & (localBlockIndex->size - 1); + + firstIndexInBlock = index; + endIndex = (index & ~static_cast<index_t>(BLOCK_SIZE - 1)) + static_cast<index_t>(BLOCK_SIZE); + endIndex = details::circular_less_than<index_t>(firstIndex + static_cast<index_t>(actualCount), endIndex) ? firstIndex + static_cast<index_t>(actualCount) : endIndex; + } while (index != firstIndex + actualCount); + + MOODYCAMEL_RETHROW; + } + } + block->ConcurrentQueue::Block::template set_many_empty<explicit_context>(firstIndexInBlock, static_cast<size_t>(endIndex - firstIndexInBlock)); + indexIndex = (indexIndex + 1) & (localBlockIndex->size - 1); + } while (index != firstIndex + actualCount); + + return actualCount; + } + else { + // Wasn't anything to dequeue after all; make the effective dequeue count eventually consistent + this->dequeueOvercommit.fetch_add(desiredCount, std::memory_order_release); + } + } + + return 0; + } + + private: + struct BlockIndexEntry + { + index_t base; + Block* block; + }; + + struct BlockIndexHeader + { + size_t size; + std::atomic<size_t> front; // Current slot (not next, like pr_blockIndexFront) + BlockIndexEntry* entries; + void* prev; + }; + + + bool new_block_index(size_t numberOfFilledSlotsToExpose) + { + auto prevBlockSizeMask = pr_blockIndexSize - 1; + + // Create the new block + pr_blockIndexSize <<= 1; + auto newRawPtr = static_cast<char*>((Traits::malloc)(sizeof(BlockIndexHeader) + std::alignment_of<BlockIndexEntry>::value - 1 + sizeof(BlockIndexEntry) * pr_blockIndexSize)); + if (newRawPtr == nullptr) { + pr_blockIndexSize >>= 1; // Reset to allow graceful retry + return false; + } + + auto newBlockIndexEntries = reinterpret_cast<BlockIndexEntry*>(details::align_for<BlockIndexEntry>(newRawPtr + sizeof(BlockIndexHeader))); + + // Copy in all the old indices, if any + size_t j = 0; + if (pr_blockIndexSlotsUsed != 0) { + auto i = (pr_blockIndexFront - pr_blockIndexSlotsUsed) & prevBlockSizeMask; + do { + newBlockIndexEntries[j++] = pr_blockIndexEntries[i]; + i = (i + 1) & prevBlockSizeMask; + } while (i != pr_blockIndexFront); + } + + // Update everything + auto header = new (newRawPtr) BlockIndexHeader; + header->size = pr_blockIndexSize; + header->front.store(numberOfFilledSlotsToExpose - 1, std::memory_order_relaxed); + header->entries = newBlockIndexEntries; + header->prev = pr_blockIndexRaw; // we link the new block to the old one so we can free it later + + pr_blockIndexFront = j; + pr_blockIndexEntries = newBlockIndexEntries; + pr_blockIndexRaw = newRawPtr; + blockIndex.store(header, std::memory_order_release); + + return true; + } + + private: + std::atomic<BlockIndexHeader*> blockIndex; + + // To be used by producer only -- consumer must use the ones in referenced by blockIndex + size_t pr_blockIndexSlotsUsed; + size_t pr_blockIndexSize; + size_t pr_blockIndexFront; // Next slot (not current) + BlockIndexEntry* pr_blockIndexEntries; + void* pr_blockIndexRaw; + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG + public: + ExplicitProducer* nextExplicitProducer; + private: +#endif + +#ifdef MCDBGQ_TRACKMEM + friend struct MemStats; +#endif + }; + + + ////////////////////////////////// + // Implicit queue + ////////////////////////////////// + + struct ImplicitProducer : public ProducerBase + { + ImplicitProducer(ConcurrentQueue* parent_) : + ProducerBase(parent_, false), + nextBlockIndexCapacity(IMPLICIT_INITIAL_INDEX_SIZE), + blockIndex(nullptr) + { + new_block_index(); + } + + ~ImplicitProducer() + { + // Note that since we're in the destructor we can assume that all enqueue/dequeue operations + // completed already; this means that all undequeued elements are placed contiguously across + // contiguous blocks, and that only the first and last remaining blocks can be only partially + // empty (all other remaining blocks must be completely full). + +#ifdef MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED + // Unregister ourselves for thread termination notification + if (!this->inactive.load(std::memory_order_relaxed)) { + details::ThreadExitNotifier::unsubscribe(&threadExitListener); + } +#endif + + // Destroy all remaining elements! + auto tail = this->tailIndex.load(std::memory_order_relaxed); + auto index = this->headIndex.load(std::memory_order_relaxed); + Block* block = nullptr; + assert(index == tail || details::circular_less_than(index, tail)); + bool forceFreeLastBlock = index != tail; // If we enter the loop, then the last (tail) block will not be freed + while (index != tail) { + if ((index & static_cast<index_t>(BLOCK_SIZE - 1)) == 0 || block == nullptr) { + if (block != nullptr) { + // Free the old block + this->parent->add_block_to_free_list(block); + } + + block = get_block_index_entry_for_index(index)->value.load(std::memory_order_relaxed); + } + + ((*block)[index])->~T(); + ++index; + } + // Even if the queue is empty, there's still one block that's not on the free list + // (unless the head index reached the end of it, in which case the tail will be poised + // to create a new block). + if (this->tailBlock != nullptr && (forceFreeLastBlock || (tail & static_cast<index_t>(BLOCK_SIZE - 1)) != 0)) { + this->parent->add_block_to_free_list(this->tailBlock); + } + + // Destroy block index + auto localBlockIndex = blockIndex.load(std::memory_order_relaxed); + if (localBlockIndex != nullptr) { + for (size_t i = 0; i != localBlockIndex->capacity; ++i) { + localBlockIndex->index[i]->~BlockIndexEntry(); + } + do { + auto prev = localBlockIndex->prev; + localBlockIndex->~BlockIndexHeader(); + (Traits::free)(localBlockIndex); + localBlockIndex = prev; + } while (localBlockIndex != nullptr); + } + } + + template<AllocationMode allocMode, typename U> + inline bool enqueue(U&& element) + { + index_t currentTailIndex = this->tailIndex.load(std::memory_order_relaxed); + index_t newTailIndex = 1 + currentTailIndex; + if ((currentTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) == 0) { + // We reached the end of a block, start a new one + auto head = this->headIndex.load(std::memory_order_relaxed); + assert(!details::circular_less_than<index_t>(currentTailIndex, head)); + if (!details::circular_less_than<index_t>(head, currentTailIndex + BLOCK_SIZE) || (MAX_SUBQUEUE_SIZE != details::const_numeric_max<size_t>::value && (MAX_SUBQUEUE_SIZE == 0 || MAX_SUBQUEUE_SIZE - BLOCK_SIZE < currentTailIndex - head))) { + return false; + } +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODBLOCKINDEX + debug::DebugLock lock(mutex); +#endif + // Find out where we'll be inserting this block in the block index + BlockIndexEntry* idxEntry; + if (!insert_block_index_entry<allocMode>(idxEntry, currentTailIndex)) { + return false; + } + + // Get ahold of a new block + auto newBlock = this->parent->ConcurrentQueue::template requisition_block<allocMode>(); + if (newBlock == nullptr) { + rewind_block_index_tail(); + idxEntry->value.store(nullptr, std::memory_order_relaxed); + return false; + } +#ifdef MCDBGQ_TRACKMEM + newBlock->owner = this; +#endif + newBlock->ConcurrentQueue::Block::template reset_empty<implicit_context>(); + + MOODYCAMEL_CONSTEXPR_IF (!MOODYCAMEL_NOEXCEPT_CTOR(T, U, new (static_cast<T*>(nullptr)) T(std::forward<U>(element)))) { + // May throw, try to insert now before we publish the fact that we have this new block + MOODYCAMEL_TRY { + new ((*newBlock)[currentTailIndex]) T(std::forward<U>(element)); + } + MOODYCAMEL_CATCH (...) { + rewind_block_index_tail(); + idxEntry->value.store(nullptr, std::memory_order_relaxed); + this->parent->add_block_to_free_list(newBlock); + MOODYCAMEL_RETHROW; + } + } + + // Insert the new block into the index + idxEntry->value.store(newBlock, std::memory_order_relaxed); + + this->tailBlock = newBlock; + + MOODYCAMEL_CONSTEXPR_IF (!MOODYCAMEL_NOEXCEPT_CTOR(T, U, new (static_cast<T*>(nullptr)) T(std::forward<U>(element)))) { + this->tailIndex.store(newTailIndex, std::memory_order_release); + return true; + } + } + + // Enqueue + new ((*this->tailBlock)[currentTailIndex]) T(std::forward<U>(element)); + + this->tailIndex.store(newTailIndex, std::memory_order_release); + return true; + } + + template<typename U> + bool dequeue(U& element) + { + // See ExplicitProducer::dequeue for rationale and explanation + index_t tail = this->tailIndex.load(std::memory_order_relaxed); + index_t overcommit = this->dequeueOvercommit.load(std::memory_order_relaxed); + if (details::circular_less_than<index_t>(this->dequeueOptimisticCount.load(std::memory_order_relaxed) - overcommit, tail)) { + std::atomic_thread_fence(std::memory_order_acquire); + + index_t myDequeueCount = this->dequeueOptimisticCount.fetch_add(1, std::memory_order_relaxed); + tail = this->tailIndex.load(std::memory_order_acquire); + if ((details::likely)(details::circular_less_than<index_t>(myDequeueCount - overcommit, tail))) { + index_t index = this->headIndex.fetch_add(1, std::memory_order_acq_rel); + + // Determine which block the element is in + auto entry = get_block_index_entry_for_index(index); + + // Dequeue + auto block = entry->value.load(std::memory_order_relaxed); + auto& el = *((*block)[index]); + + if (!MOODYCAMEL_NOEXCEPT_ASSIGN(T, T&&, element = std::move(el))) { +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODBLOCKINDEX + // Note: Acquiring the mutex with every dequeue instead of only when a block + // is released is very sub-optimal, but it is, after all, purely debug code. + debug::DebugLock lock(producer->mutex); +#endif + struct Guard { + Block* block; + index_t index; + BlockIndexEntry* entry; + ConcurrentQueue* parent; + + ~Guard() + { + (*block)[index]->~T(); + if (block->ConcurrentQueue::Block::template set_empty<implicit_context>(index)) { + entry->value.store(nullptr, std::memory_order_relaxed); + parent->add_block_to_free_list(block); + } + } + } guard = { block, index, entry, this->parent }; + + element = std::move(el); // NOLINT + } + else { + element = std::move(el); // NOLINT + el.~T(); // NOLINT + + if (block->ConcurrentQueue::Block::template set_empty<implicit_context>(index)) { + { +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODBLOCKINDEX + debug::DebugLock lock(mutex); +#endif + // Add the block back into the global free pool (and remove from block index) + entry->value.store(nullptr, std::memory_order_relaxed); + } + this->parent->add_block_to_free_list(block); // releases the above store + } + } + + return true; + } + else { + this->dequeueOvercommit.fetch_add(1, std::memory_order_release); + } + } + + return false; + } + +#ifdef _MSC_VER +#pragma warning(push) +#pragma warning(disable: 4706) // assignment within conditional expression +#endif + template<AllocationMode allocMode, typename It> + bool enqueue_bulk(It itemFirst, size_t count) + { + // First, we need to make sure we have enough room to enqueue all of the elements; + // this means pre-allocating blocks and putting them in the block index (but only if + // all the allocations succeeded). + + // Note that the tailBlock we start off with may not be owned by us any more; + // this happens if it was filled up exactly to the top (setting tailIndex to + // the first index of the next block which is not yet allocated), then dequeued + // completely (putting it on the free list) before we enqueue again. + + index_t startTailIndex = this->tailIndex.load(std::memory_order_relaxed); + auto startBlock = this->tailBlock; + Block* firstAllocatedBlock = nullptr; + auto endBlock = this->tailBlock; + + // Figure out how many blocks we'll need to allocate, and do so + size_t blockBaseDiff = ((startTailIndex + count - 1) & ~static_cast<index_t>(BLOCK_SIZE - 1)) - ((startTailIndex - 1) & ~static_cast<index_t>(BLOCK_SIZE - 1)); + index_t currentTailIndex = (startTailIndex - 1) & ~static_cast<index_t>(BLOCK_SIZE - 1); + if (blockBaseDiff > 0) { +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODBLOCKINDEX + debug::DebugLock lock(mutex); +#endif + do { + blockBaseDiff -= static_cast<index_t>(BLOCK_SIZE); + currentTailIndex += static_cast<index_t>(BLOCK_SIZE); + + // Find out where we'll be inserting this block in the block index + BlockIndexEntry* idxEntry = nullptr; // initialization here unnecessary but compiler can't always tell + Block* newBlock; + bool indexInserted = false; + auto head = this->headIndex.load(std::memory_order_relaxed); + assert(!details::circular_less_than<index_t>(currentTailIndex, head)); + bool full = !details::circular_less_than<index_t>(head, currentTailIndex + BLOCK_SIZE) || (MAX_SUBQUEUE_SIZE != details::const_numeric_max<size_t>::value && (MAX_SUBQUEUE_SIZE == 0 || MAX_SUBQUEUE_SIZE - BLOCK_SIZE < currentTailIndex - head)); + + if (full || !(indexInserted = insert_block_index_entry<allocMode>(idxEntry, currentTailIndex)) || (newBlock = this->parent->ConcurrentQueue::template requisition_block<allocMode>()) == nullptr) { + // Index allocation or block allocation failed; revert any other allocations + // and index insertions done so far for this operation + if (indexInserted) { + rewind_block_index_tail(); + idxEntry->value.store(nullptr, std::memory_order_relaxed); + } + currentTailIndex = (startTailIndex - 1) & ~static_cast<index_t>(BLOCK_SIZE - 1); + for (auto block = firstAllocatedBlock; block != nullptr; block = block->next) { + currentTailIndex += static_cast<index_t>(BLOCK_SIZE); + idxEntry = get_block_index_entry_for_index(currentTailIndex); + idxEntry->value.store(nullptr, std::memory_order_relaxed); + rewind_block_index_tail(); + } + this->parent->add_blocks_to_free_list(firstAllocatedBlock); + this->tailBlock = startBlock; + + return false; + } + +#ifdef MCDBGQ_TRACKMEM + newBlock->owner = this; +#endif + newBlock->ConcurrentQueue::Block::template reset_empty<implicit_context>(); + newBlock->next = nullptr; + + // Insert the new block into the index + idxEntry->value.store(newBlock, std::memory_order_relaxed); + + // Store the chain of blocks so that we can undo if later allocations fail, + // and so that we can find the blocks when we do the actual enqueueing + if ((startTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) != 0 || firstAllocatedBlock != nullptr) { + assert(this->tailBlock != nullptr); + this->tailBlock->next = newBlock; + } + this->tailBlock = newBlock; + endBlock = newBlock; + firstAllocatedBlock = firstAllocatedBlock == nullptr ? newBlock : firstAllocatedBlock; + } while (blockBaseDiff > 0); + } + + // Enqueue, one block at a time + index_t newTailIndex = startTailIndex + static_cast<index_t>(count); + currentTailIndex = startTailIndex; + this->tailBlock = startBlock; + assert((startTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) != 0 || firstAllocatedBlock != nullptr || count == 0); + if ((startTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) == 0 && firstAllocatedBlock != nullptr) { + this->tailBlock = firstAllocatedBlock; + } + while (true) { + index_t stopIndex = (currentTailIndex & ~static_cast<index_t>(BLOCK_SIZE - 1)) + static_cast<index_t>(BLOCK_SIZE); + if (details::circular_less_than<index_t>(newTailIndex, stopIndex)) { + stopIndex = newTailIndex; + } + MOODYCAMEL_CONSTEXPR_IF (MOODYCAMEL_NOEXCEPT_CTOR(T, decltype(*itemFirst), new (static_cast<T*>(nullptr)) T(details::deref_noexcept(itemFirst)))) { + while (currentTailIndex != stopIndex) { + new ((*this->tailBlock)[currentTailIndex++]) T(*itemFirst++); + } + } + else { + MOODYCAMEL_TRY { + while (currentTailIndex != stopIndex) { + new ((*this->tailBlock)[currentTailIndex]) T(details::nomove_if<!MOODYCAMEL_NOEXCEPT_CTOR(T, decltype(*itemFirst), new (static_cast<T*>(nullptr)) T(details::deref_noexcept(itemFirst)))>::eval(*itemFirst)); + ++currentTailIndex; + ++itemFirst; + } + } + MOODYCAMEL_CATCH (...) { + auto constructedStopIndex = currentTailIndex; + auto lastBlockEnqueued = this->tailBlock; + + if (!details::is_trivially_destructible<T>::value) { + auto block = startBlock; + if ((startTailIndex & static_cast<index_t>(BLOCK_SIZE - 1)) == 0) { + block = firstAllocatedBlock; + } + currentTailIndex = startTailIndex; + while (true) { + stopIndex = (currentTailIndex & ~static_cast<index_t>(BLOCK_SIZE - 1)) + static_cast<index_t>(BLOCK_SIZE); + if (details::circular_less_than<index_t>(constructedStopIndex, stopIndex)) { + stopIndex = constructedStopIndex; + } + while (currentTailIndex != stopIndex) { + (*block)[currentTailIndex++]->~T(); + } + if (block == lastBlockEnqueued) { + break; + } + block = block->next; + } + } + + currentTailIndex = (startTailIndex - 1) & ~static_cast<index_t>(BLOCK_SIZE - 1); + for (auto block = firstAllocatedBlock; block != nullptr; block = block->next) { + currentTailIndex += static_cast<index_t>(BLOCK_SIZE); + auto idxEntry = get_block_index_entry_for_index(currentTailIndex); + idxEntry->value.store(nullptr, std::memory_order_relaxed); + rewind_block_index_tail(); + } + this->parent->add_blocks_to_free_list(firstAllocatedBlock); + this->tailBlock = startBlock; + MOODYCAMEL_RETHROW; + } + } + + if (this->tailBlock == endBlock) { + assert(currentTailIndex == newTailIndex); + break; + } + this->tailBlock = this->tailBlock->next; + } + this->tailIndex.store(newTailIndex, std::memory_order_release); + return true; + } +#ifdef _MSC_VER +#pragma warning(pop) +#endif + + template<typename It> + size_t dequeue_bulk(It& itemFirst, size_t max) + { + auto tail = this->tailIndex.load(std::memory_order_relaxed); + auto overcommit = this->dequeueOvercommit.load(std::memory_order_relaxed); + auto desiredCount = static_cast<size_t>(tail - (this->dequeueOptimisticCount.load(std::memory_order_relaxed) - overcommit)); + if (details::circular_less_than<size_t>(0, desiredCount)) { + desiredCount = desiredCount < max ? desiredCount : max; + std::atomic_thread_fence(std::memory_order_acquire); + + auto myDequeueCount = this->dequeueOptimisticCount.fetch_add(desiredCount, std::memory_order_relaxed); + + tail = this->tailIndex.load(std::memory_order_acquire); + auto actualCount = static_cast<size_t>(tail - (myDequeueCount - overcommit)); + if (details::circular_less_than<size_t>(0, actualCount)) { + actualCount = desiredCount < actualCount ? desiredCount : actualCount; + if (actualCount < desiredCount) { + this->dequeueOvercommit.fetch_add(desiredCount - actualCount, std::memory_order_release); + } + + // Get the first index. Note that since there's guaranteed to be at least actualCount elements, this + // will never exceed tail. + auto firstIndex = this->headIndex.fetch_add(actualCount, std::memory_order_acq_rel); + + // Iterate the blocks and dequeue + auto index = firstIndex; + BlockIndexHeader* localBlockIndex; + auto indexIndex = get_block_index_index_for_index(index, localBlockIndex); + do { + auto blockStartIndex = index; + index_t endIndex = (index & ~static_cast<index_t>(BLOCK_SIZE - 1)) + static_cast<index_t>(BLOCK_SIZE); + endIndex = details::circular_less_than<index_t>(firstIndex + static_cast<index_t>(actualCount), endIndex) ? firstIndex + static_cast<index_t>(actualCount) : endIndex; + + auto entry = localBlockIndex->index[indexIndex]; + auto block = entry->value.load(std::memory_order_relaxed); + if (MOODYCAMEL_NOEXCEPT_ASSIGN(T, T&&, details::deref_noexcept(itemFirst) = std::move((*(*block)[index])))) { + while (index != endIndex) { + auto& el = *((*block)[index]); + *itemFirst++ = std::move(el); + el.~T(); + ++index; + } + } + else { + MOODYCAMEL_TRY { + while (index != endIndex) { + auto& el = *((*block)[index]); + *itemFirst = std::move(el); + ++itemFirst; + el.~T(); + ++index; + } + } + MOODYCAMEL_CATCH (...) { + do { + entry = localBlockIndex->index[indexIndex]; + block = entry->value.load(std::memory_order_relaxed); + while (index != endIndex) { + (*block)[index++]->~T(); + } + + if (block->ConcurrentQueue::Block::template set_many_empty<implicit_context>(blockStartIndex, static_cast<size_t>(endIndex - blockStartIndex))) { +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODBLOCKINDEX + debug::DebugLock lock(mutex); +#endif + entry->value.store(nullptr, std::memory_order_relaxed); + this->parent->add_block_to_free_list(block); + } + indexIndex = (indexIndex + 1) & (localBlockIndex->capacity - 1); + + blockStartIndex = index; + endIndex = (index & ~static_cast<index_t>(BLOCK_SIZE - 1)) + static_cast<index_t>(BLOCK_SIZE); + endIndex = details::circular_less_than<index_t>(firstIndex + static_cast<index_t>(actualCount), endIndex) ? firstIndex + static_cast<index_t>(actualCount) : endIndex; + } while (index != firstIndex + actualCount); + + MOODYCAMEL_RETHROW; + } + } + if (block->ConcurrentQueue::Block::template set_many_empty<implicit_context>(blockStartIndex, static_cast<size_t>(endIndex - blockStartIndex))) { + { +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODBLOCKINDEX + debug::DebugLock lock(mutex); +#endif + // Note that the set_many_empty above did a release, meaning that anybody who acquires the block + // we're about to free can use it safely since our writes (and reads!) will have happened-before then. + entry->value.store(nullptr, std::memory_order_relaxed); + } + this->parent->add_block_to_free_list(block); // releases the above store + } + indexIndex = (indexIndex + 1) & (localBlockIndex->capacity - 1); + } while (index != firstIndex + actualCount); + + return actualCount; + } + else { + this->dequeueOvercommit.fetch_add(desiredCount, std::memory_order_release); + } + } + + return 0; + } + + private: + // The block size must be > 1, so any number with the low bit set is an invalid block base index + static const index_t INVALID_BLOCK_BASE = 1; + + struct BlockIndexEntry + { + std::atomic<index_t> key; + std::atomic<Block*> value; + }; + + struct BlockIndexHeader + { + size_t capacity; + std::atomic<size_t> tail; + BlockIndexEntry* entries; + BlockIndexEntry** index; + BlockIndexHeader* prev; + }; + + template<AllocationMode allocMode> + inline bool insert_block_index_entry(BlockIndexEntry*& idxEntry, index_t blockStartIndex) + { + auto localBlockIndex = blockIndex.load(std::memory_order_relaxed); // We're the only writer thread, relaxed is OK + if (localBlockIndex == nullptr) { + return false; // this can happen if new_block_index failed in the constructor + } + size_t newTail = (localBlockIndex->tail.load(std::memory_order_relaxed) + 1) & (localBlockIndex->capacity - 1); + idxEntry = localBlockIndex->index[newTail]; + if (idxEntry->key.load(std::memory_order_relaxed) == INVALID_BLOCK_BASE || + idxEntry->value.load(std::memory_order_relaxed) == nullptr) { + + idxEntry->key.store(blockStartIndex, std::memory_order_relaxed); + localBlockIndex->tail.store(newTail, std::memory_order_release); + return true; + } + + // No room in the old block index, try to allocate another one! + MOODYCAMEL_CONSTEXPR_IF (allocMode == CannotAlloc) { + return false; + } + else if (!new_block_index()) { + return false; + } + else { + localBlockIndex = blockIndex.load(std::memory_order_relaxed); + newTail = (localBlockIndex->tail.load(std::memory_order_relaxed) + 1) & (localBlockIndex->capacity - 1); + idxEntry = localBlockIndex->index[newTail]; + assert(idxEntry->key.load(std::memory_order_relaxed) == INVALID_BLOCK_BASE); + idxEntry->key.store(blockStartIndex, std::memory_order_relaxed); + localBlockIndex->tail.store(newTail, std::memory_order_release); + return true; + } + } + + inline void rewind_block_index_tail() + { + auto localBlockIndex = blockIndex.load(std::memory_order_relaxed); + localBlockIndex->tail.store((localBlockIndex->tail.load(std::memory_order_relaxed) - 1) & (localBlockIndex->capacity - 1), std::memory_order_relaxed); + } + + inline BlockIndexEntry* get_block_index_entry_for_index(index_t index) const + { + BlockIndexHeader* localBlockIndex; + auto idx = get_block_index_index_for_index(index, localBlockIndex); + return localBlockIndex->index[idx]; + } + + inline size_t get_block_index_index_for_index(index_t index, BlockIndexHeader*& localBlockIndex) const + { +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODBLOCKINDEX + debug::DebugLock lock(mutex); +#endif + index &= ~static_cast<index_t>(BLOCK_SIZE - 1); + localBlockIndex = blockIndex.load(std::memory_order_acquire); + auto tail = localBlockIndex->tail.load(std::memory_order_acquire); + auto tailBase = localBlockIndex->index[tail]->key.load(std::memory_order_relaxed); + assert(tailBase != INVALID_BLOCK_BASE); + // Note: Must use division instead of shift because the index may wrap around, causing a negative + // offset, whose negativity we want to preserve + auto offset = static_cast<size_t>(static_cast<typename std::make_signed<index_t>::type>(index - tailBase) / static_cast<typename std::make_signed<index_t>::type>(BLOCK_SIZE)); + size_t idx = (tail + offset) & (localBlockIndex->capacity - 1); + assert(localBlockIndex->index[idx]->key.load(std::memory_order_relaxed) == index && localBlockIndex->index[idx]->value.load(std::memory_order_relaxed) != nullptr); + return idx; + } + + bool new_block_index() + { + auto prev = blockIndex.load(std::memory_order_relaxed); + size_t prevCapacity = prev == nullptr ? 0 : prev->capacity; + auto entryCount = prev == nullptr ? nextBlockIndexCapacity : prevCapacity; + auto raw = static_cast<char*>((Traits::malloc)( + sizeof(BlockIndexHeader) + + std::alignment_of<BlockIndexEntry>::value - 1 + sizeof(BlockIndexEntry) * entryCount + + std::alignment_of<BlockIndexEntry*>::value - 1 + sizeof(BlockIndexEntry*) * nextBlockIndexCapacity)); + if (raw == nullptr) { + return false; + } + + auto header = new (raw) BlockIndexHeader; + auto entries = reinterpret_cast<BlockIndexEntry*>(details::align_for<BlockIndexEntry>(raw + sizeof(BlockIndexHeader))); + auto index = reinterpret_cast<BlockIndexEntry**>(details::align_for<BlockIndexEntry*>(reinterpret_cast<char*>(entries) + sizeof(BlockIndexEntry) * entryCount)); + if (prev != nullptr) { + auto prevTail = prev->tail.load(std::memory_order_relaxed); + auto prevPos = prevTail; + size_t i = 0; + do { + prevPos = (prevPos + 1) & (prev->capacity - 1); + index[i++] = prev->index[prevPos]; + } while (prevPos != prevTail); + assert(i == prevCapacity); + } + for (size_t i = 0; i != entryCount; ++i) { + new (entries + i) BlockIndexEntry; + entries[i].key.store(INVALID_BLOCK_BASE, std::memory_order_relaxed); + index[prevCapacity + i] = entries + i; + } + header->prev = prev; + header->entries = entries; + header->index = index; + header->capacity = nextBlockIndexCapacity; + header->tail.store((prevCapacity - 1) & (nextBlockIndexCapacity - 1), std::memory_order_relaxed); + + blockIndex.store(header, std::memory_order_release); + + nextBlockIndexCapacity <<= 1; + + return true; + } + + private: + size_t nextBlockIndexCapacity; + std::atomic<BlockIndexHeader*> blockIndex; + +#ifdef MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED + public: + details::ThreadExitListener threadExitListener; + private: +#endif + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG + public: + ImplicitProducer* nextImplicitProducer; + private: +#endif + +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODBLOCKINDEX + mutable debug::DebugMutex mutex; +#endif +#ifdef MCDBGQ_TRACKMEM + friend struct MemStats; +#endif + }; + + + ////////////////////////////////// + // Block pool manipulation + ////////////////////////////////// + + void populate_initial_block_list(size_t blockCount) + { + initialBlockPoolSize = blockCount; + if (initialBlockPoolSize == 0) { + initialBlockPool = nullptr; + return; + } + + initialBlockPool = create_array<Block>(blockCount); + if (initialBlockPool == nullptr) { + initialBlockPoolSize = 0; + } + for (size_t i = 0; i < initialBlockPoolSize; ++i) { + initialBlockPool[i].dynamicallyAllocated = false; + } + } + + inline Block* try_get_block_from_initial_pool() + { + if (initialBlockPoolIndex.load(std::memory_order_relaxed) >= initialBlockPoolSize) { + return nullptr; + } + + auto index = initialBlockPoolIndex.fetch_add(1, std::memory_order_relaxed); + + return index < initialBlockPoolSize ? (initialBlockPool + index) : nullptr; + } + + inline void add_block_to_free_list(Block* block) + { +#ifdef MCDBGQ_TRACKMEM + block->owner = nullptr; +#endif + if (!Traits::RECYCLE_ALLOCATED_BLOCKS && block->dynamicallyAllocated) { + destroy(block); + } + else { + freeList.add(block); + } + } + + inline void add_blocks_to_free_list(Block* block) + { + while (block != nullptr) { + auto next = block->next; + add_block_to_free_list(block); + block = next; + } + } + + inline Block* try_get_block_from_free_list() + { + return freeList.try_get(); + } + + // Gets a free block from one of the memory pools, or allocates a new one (if applicable) + template<AllocationMode canAlloc> + Block* requisition_block() + { + auto block = try_get_block_from_initial_pool(); + if (block != nullptr) { + return block; + } + + block = try_get_block_from_free_list(); + if (block != nullptr) { + return block; + } + + MOODYCAMEL_CONSTEXPR_IF (canAlloc == CanAlloc) { + return create<Block>(); + } + else { + return nullptr; + } + } + + +#ifdef MCDBGQ_TRACKMEM + public: + struct MemStats { + size_t allocatedBlocks; + size_t usedBlocks; + size_t freeBlocks; + size_t ownedBlocksExplicit; + size_t ownedBlocksImplicit; + size_t implicitProducers; + size_t explicitProducers; + size_t elementsEnqueued; + size_t blockClassBytes; + size_t queueClassBytes; + size_t implicitBlockIndexBytes; + size_t explicitBlockIndexBytes; + + friend class ConcurrentQueue; + + private: + static MemStats getFor(ConcurrentQueue* q) + { + MemStats stats = { 0 }; + + stats.elementsEnqueued = q->size_approx(); + + auto block = q->freeList.head_unsafe(); + while (block != nullptr) { + ++stats.allocatedBlocks; + ++stats.freeBlocks; + block = block->freeListNext.load(std::memory_order_relaxed); + } + + for (auto ptr = q->producerListTail.load(std::memory_order_acquire); ptr != nullptr; ptr = ptr->next_prod()) { + bool implicit = dynamic_cast<ImplicitProducer*>(ptr) != nullptr; + stats.implicitProducers += implicit ? 1 : 0; + stats.explicitProducers += implicit ? 0 : 1; + + if (implicit) { + auto prod = static_cast<ImplicitProducer*>(ptr); + stats.queueClassBytes += sizeof(ImplicitProducer); + auto head = prod->headIndex.load(std::memory_order_relaxed); + auto tail = prod->tailIndex.load(std::memory_order_relaxed); + auto hash = prod->blockIndex.load(std::memory_order_relaxed); + if (hash != nullptr) { + for (size_t i = 0; i != hash->capacity; ++i) { + if (hash->index[i]->key.load(std::memory_order_relaxed) != ImplicitProducer::INVALID_BLOCK_BASE && hash->index[i]->value.load(std::memory_order_relaxed) != nullptr) { + ++stats.allocatedBlocks; + ++stats.ownedBlocksImplicit; + } + } + stats.implicitBlockIndexBytes += hash->capacity * sizeof(typename ImplicitProducer::BlockIndexEntry); + for (; hash != nullptr; hash = hash->prev) { + stats.implicitBlockIndexBytes += sizeof(typename ImplicitProducer::BlockIndexHeader) + hash->capacity * sizeof(typename ImplicitProducer::BlockIndexEntry*); + } + } + for (; details::circular_less_than<index_t>(head, tail); head += BLOCK_SIZE) { + //auto block = prod->get_block_index_entry_for_index(head); + ++stats.usedBlocks; + } + } + else { + auto prod = static_cast<ExplicitProducer*>(ptr); + stats.queueClassBytes += sizeof(ExplicitProducer); + auto tailBlock = prod->tailBlock; + bool wasNonEmpty = false; + if (tailBlock != nullptr) { + auto block = tailBlock; + do { + ++stats.allocatedBlocks; + if (!block->ConcurrentQueue::Block::template is_empty<explicit_context>() || wasNonEmpty) { + ++stats.usedBlocks; + wasNonEmpty = wasNonEmpty || block != tailBlock; + } + ++stats.ownedBlocksExplicit; + block = block->next; + } while (block != tailBlock); + } + auto index = prod->blockIndex.load(std::memory_order_relaxed); + while (index != nullptr) { + stats.explicitBlockIndexBytes += sizeof(typename ExplicitProducer::BlockIndexHeader) + index->size * sizeof(typename ExplicitProducer::BlockIndexEntry); + index = static_cast<typename ExplicitProducer::BlockIndexHeader*>(index->prev); + } + } + } + + auto freeOnInitialPool = q->initialBlockPoolIndex.load(std::memory_order_relaxed) >= q->initialBlockPoolSize ? 0 : q->initialBlockPoolSize - q->initialBlockPoolIndex.load(std::memory_order_relaxed); + stats.allocatedBlocks += freeOnInitialPool; + stats.freeBlocks += freeOnInitialPool; + + stats.blockClassBytes = sizeof(Block) * stats.allocatedBlocks; + stats.queueClassBytes += sizeof(ConcurrentQueue); + + return stats; + } + }; + + // For debugging only. Not thread-safe. + MemStats getMemStats() + { + return MemStats::getFor(this); + } + private: + friend struct MemStats; +#endif + + + ////////////////////////////////// + // Producer list manipulation + ////////////////////////////////// + + ProducerBase* recycle_or_create_producer(bool isExplicit) + { +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODHASH + debug::DebugLock lock(implicitProdMutex); +#endif + // Try to re-use one first + for (auto ptr = producerListTail.load(std::memory_order_acquire); ptr != nullptr; ptr = ptr->next_prod()) { + if (ptr->inactive.load(std::memory_order_relaxed) && ptr->isExplicit == isExplicit) { + bool expected = true; + if (ptr->inactive.compare_exchange_strong(expected, /* desired */ false, std::memory_order_acquire, std::memory_order_relaxed)) { + // We caught one! It's been marked as activated, the caller can have it + return ptr; + } + } + } + + return add_producer(isExplicit ? static_cast<ProducerBase*>(create<ExplicitProducer>(this)) : create<ImplicitProducer>(this)); + } + + ProducerBase* add_producer(ProducerBase* producer) + { + // Handle failed memory allocation + if (producer == nullptr) { + return nullptr; + } + + producerCount.fetch_add(1, std::memory_order_relaxed); + + // Add it to the lock-free list + auto prevTail = producerListTail.load(std::memory_order_relaxed); + do { + producer->next = prevTail; + } while (!producerListTail.compare_exchange_weak(prevTail, producer, std::memory_order_release, std::memory_order_relaxed)); + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG + if (producer->isExplicit) { + auto prevTailExplicit = explicitProducers.load(std::memory_order_relaxed); + do { + static_cast<ExplicitProducer*>(producer)->nextExplicitProducer = prevTailExplicit; + } while (!explicitProducers.compare_exchange_weak(prevTailExplicit, static_cast<ExplicitProducer*>(producer), std::memory_order_release, std::memory_order_relaxed)); + } + else { + auto prevTailImplicit = implicitProducers.load(std::memory_order_relaxed); + do { + static_cast<ImplicitProducer*>(producer)->nextImplicitProducer = prevTailImplicit; + } while (!implicitProducers.compare_exchange_weak(prevTailImplicit, static_cast<ImplicitProducer*>(producer), std::memory_order_release, std::memory_order_relaxed)); + } +#endif + + return producer; + } + + void reown_producers() + { + // After another instance is moved-into/swapped-with this one, all the + // producers we stole still think their parents are the other queue. + // So fix them up! + for (auto ptr = producerListTail.load(std::memory_order_relaxed); ptr != nullptr; ptr = ptr->next_prod()) { + ptr->parent = this; + } + } + + + ////////////////////////////////// + // Implicit producer hash + ////////////////////////////////// + + struct ImplicitProducerKVP + { + std::atomic<details::thread_id_t> key; + ImplicitProducer* value; // No need for atomicity since it's only read by the thread that sets it in the first place + + ImplicitProducerKVP() : value(nullptr) { } + + ImplicitProducerKVP(ImplicitProducerKVP&& other) MOODYCAMEL_NOEXCEPT + { + key.store(other.key.load(std::memory_order_relaxed), std::memory_order_relaxed); + value = other.value; + } + + inline ImplicitProducerKVP& operator=(ImplicitProducerKVP&& other) MOODYCAMEL_NOEXCEPT + { + swap(other); + return *this; + } + + inline void swap(ImplicitProducerKVP& other) MOODYCAMEL_NOEXCEPT + { + if (this != &other) { + details::swap_relaxed(key, other.key); + std::swap(value, other.value); + } + } + }; + + template<typename XT, typename XTraits> + friend void moodycamel::swap(typename ConcurrentQueue<XT, XTraits>::ImplicitProducerKVP&, typename ConcurrentQueue<XT, XTraits>::ImplicitProducerKVP&) MOODYCAMEL_NOEXCEPT; + + struct ImplicitProducerHash + { + size_t capacity; + ImplicitProducerKVP* entries; + ImplicitProducerHash* prev; + }; + + inline void populate_initial_implicit_producer_hash() + { + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) { + return; + } + else { + implicitProducerHashCount.store(0, std::memory_order_relaxed); + auto hash = &initialImplicitProducerHash; + hash->capacity = INITIAL_IMPLICIT_PRODUCER_HASH_SIZE; + hash->entries = &initialImplicitProducerHashEntries[0]; + for (size_t i = 0; i != INITIAL_IMPLICIT_PRODUCER_HASH_SIZE; ++i) { + initialImplicitProducerHashEntries[i].key.store(details::invalid_thread_id, std::memory_order_relaxed); + } + hash->prev = nullptr; + implicitProducerHash.store(hash, std::memory_order_relaxed); + } + } + + void swap_implicit_producer_hashes(ConcurrentQueue& other) + { + MOODYCAMEL_CONSTEXPR_IF (INITIAL_IMPLICIT_PRODUCER_HASH_SIZE == 0) { + return; + } + else { + // Swap (assumes our implicit producer hash is initialized) + initialImplicitProducerHashEntries.swap(other.initialImplicitProducerHashEntries); + initialImplicitProducerHash.entries = &initialImplicitProducerHashEntries[0]; + other.initialImplicitProducerHash.entries = &other.initialImplicitProducerHashEntries[0]; + + details::swap_relaxed(implicitProducerHashCount, other.implicitProducerHashCount); + + details::swap_relaxed(implicitProducerHash, other.implicitProducerHash); + if (implicitProducerHash.load(std::memory_order_relaxed) == &other.initialImplicitProducerHash) { + implicitProducerHash.store(&initialImplicitProducerHash, std::memory_order_relaxed); + } + else { + ImplicitProducerHash* hash; + for (hash = implicitProducerHash.load(std::memory_order_relaxed); hash->prev != &other.initialImplicitProducerHash; hash = hash->prev) { + continue; + } + hash->prev = &initialImplicitProducerHash; + } + if (other.implicitProducerHash.load(std::memory_order_relaxed) == &initialImplicitProducerHash) { + other.implicitProducerHash.store(&other.initialImplicitProducerHash, std::memory_order_relaxed); + } + else { + ImplicitProducerHash* hash; + for (hash = other.implicitProducerHash.load(std::memory_order_relaxed); hash->prev != &initialImplicitProducerHash; hash = hash->prev) { + continue; + } + hash->prev = &other.initialImplicitProducerHash; + } + } + } + + // Only fails (returns nullptr) if memory allocation fails + ImplicitProducer* get_or_add_implicit_producer() + { + // Note that since the data is essentially thread-local (key is thread ID), + // there's a reduced need for fences (memory ordering is already consistent + // for any individual thread), except for the current table itself. + + // Start by looking for the thread ID in the current and all previous hash tables. + // If it's not found, it must not be in there yet, since this same thread would + // have added it previously to one of the tables that we traversed. + + // Code and algorithm adapted from http://preshing.com/20130605/the-worlds-simplest-lock-free-hash-table + +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODHASH + debug::DebugLock lock(implicitProdMutex); +#endif + + auto id = details::thread_id(); + auto hashedId = details::hash_thread_id(id); + + auto mainHash = implicitProducerHash.load(std::memory_order_acquire); + assert(mainHash != nullptr); // silence clang-tidy and MSVC warnings (hash cannot be null) + for (auto hash = mainHash; hash != nullptr; hash = hash->prev) { + // Look for the id in this hash + auto index = hashedId; + while (true) { // Not an infinite loop because at least one slot is free in the hash table + index &= hash->capacity - 1u; + + auto probedKey = hash->entries[index].key.load(std::memory_order_relaxed); + if (probedKey == id) { + // Found it! If we had to search several hashes deep, though, we should lazily add it + // to the current main hash table to avoid the extended search next time. + // Note there's guaranteed to be room in the current hash table since every subsequent + // table implicitly reserves space for all previous tables (there's only one + // implicitProducerHashCount). + auto value = hash->entries[index].value; + if (hash != mainHash) { + index = hashedId; + while (true) { + index &= mainHash->capacity - 1u; + auto empty = details::invalid_thread_id; +#ifdef MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED + auto reusable = details::invalid_thread_id2; + if (mainHash->entries[index].key.compare_exchange_strong(empty, id, std::memory_order_seq_cst, std::memory_order_relaxed) || + mainHash->entries[index].key.compare_exchange_strong(reusable, id, std::memory_order_seq_cst, std::memory_order_relaxed)) { +#else + if (mainHash->entries[index].key.compare_exchange_strong(empty, id, std::memory_order_seq_cst, std::memory_order_relaxed)) { +#endif + mainHash->entries[index].value = value; + break; + } + ++index; + } + } + + return value; + } + if (probedKey == details::invalid_thread_id) { + break; // Not in this hash table + } + ++index; + } + } + + // Insert! + auto newCount = 1 + implicitProducerHashCount.fetch_add(1, std::memory_order_relaxed); + while (true) { + // NOLINTNEXTLINE(clang-analyzer-core.NullDereference) + if (newCount >= (mainHash->capacity >> 1) && !implicitProducerHashResizeInProgress.test_and_set(std::memory_order_acquire)) { + // We've acquired the resize lock, try to allocate a bigger hash table. + // Note the acquire fence synchronizes with the release fence at the end of this block, and hence when + // we reload implicitProducerHash it must be the most recent version (it only gets changed within this + // locked block). + mainHash = implicitProducerHash.load(std::memory_order_acquire); + if (newCount >= (mainHash->capacity >> 1)) { + size_t newCapacity = mainHash->capacity << 1; + while (newCount >= (newCapacity >> 1)) { + newCapacity <<= 1; + } + auto raw = static_cast<char*>((Traits::malloc)(sizeof(ImplicitProducerHash) + std::alignment_of<ImplicitProducerKVP>::value - 1 + sizeof(ImplicitProducerKVP) * newCapacity)); + if (raw == nullptr) { + // Allocation failed + implicitProducerHashCount.fetch_sub(1, std::memory_order_relaxed); + implicitProducerHashResizeInProgress.clear(std::memory_order_relaxed); + return nullptr; + } + + auto newHash = new (raw) ImplicitProducerHash; + newHash->capacity = static_cast<size_t>(newCapacity); + newHash->entries = reinterpret_cast<ImplicitProducerKVP*>(details::align_for<ImplicitProducerKVP>(raw + sizeof(ImplicitProducerHash))); + for (size_t i = 0; i != newCapacity; ++i) { + new (newHash->entries + i) ImplicitProducerKVP; + newHash->entries[i].key.store(details::invalid_thread_id, std::memory_order_relaxed); + } + newHash->prev = mainHash; + implicitProducerHash.store(newHash, std::memory_order_release); + implicitProducerHashResizeInProgress.clear(std::memory_order_release); + mainHash = newHash; + } + else { + implicitProducerHashResizeInProgress.clear(std::memory_order_release); + } + } + + // If it's < three-quarters full, add to the old one anyway so that we don't have to wait for the next table + // to finish being allocated by another thread (and if we just finished allocating above, the condition will + // always be true) + if (newCount < (mainHash->capacity >> 1) + (mainHash->capacity >> 2)) { + auto producer = static_cast<ImplicitProducer*>(recycle_or_create_producer(false)); + if (producer == nullptr) { + implicitProducerHashCount.fetch_sub(1, std::memory_order_relaxed); + return nullptr; + } + +#ifdef MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED + producer->threadExitListener.callback = &ConcurrentQueue::implicit_producer_thread_exited_callback; + producer->threadExitListener.userData = producer; + details::ThreadExitNotifier::subscribe(&producer->threadExitListener); +#endif + + auto index = hashedId; + while (true) { + index &= mainHash->capacity - 1u; + auto empty = details::invalid_thread_id; +#ifdef MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED + auto reusable = details::invalid_thread_id2; + if (mainHash->entries[index].key.compare_exchange_strong(reusable, id, std::memory_order_seq_cst, std::memory_order_relaxed)) { + implicitProducerHashCount.fetch_sub(1, std::memory_order_relaxed); // already counted as a used slot + mainHash->entries[index].value = producer; + break; + } +#endif + if (mainHash->entries[index].key.compare_exchange_strong(empty, id, std::memory_order_seq_cst, std::memory_order_relaxed)) { + mainHash->entries[index].value = producer; + break; + } + ++index; + } + return producer; + } + + // Hmm, the old hash is quite full and somebody else is busy allocating a new one. + // We need to wait for the allocating thread to finish (if it succeeds, we add, if not, + // we try to allocate ourselves). + mainHash = implicitProducerHash.load(std::memory_order_acquire); + } + } + +#ifdef MOODYCAMEL_CPP11_THREAD_LOCAL_SUPPORTED + void implicit_producer_thread_exited(ImplicitProducer* producer) + { + // Remove from hash +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODHASH + debug::DebugLock lock(implicitProdMutex); +#endif + auto hash = implicitProducerHash.load(std::memory_order_acquire); + assert(hash != nullptr); // The thread exit listener is only registered if we were added to a hash in the first place + auto id = details::thread_id(); + auto hashedId = details::hash_thread_id(id); + details::thread_id_t probedKey; + + // We need to traverse all the hashes just in case other threads aren't on the current one yet and are + // trying to add an entry thinking there's a free slot (because they reused a producer) + for (; hash != nullptr; hash = hash->prev) { + auto index = hashedId; + do { + index &= hash->capacity - 1u; + probedKey = id; + if (hash->entries[index].key.compare_exchange_strong(probedKey, details::invalid_thread_id2, std::memory_order_seq_cst, std::memory_order_relaxed)) { + break; + } + ++index; + } while (probedKey != details::invalid_thread_id); // Can happen if the hash has changed but we weren't put back in it yet, or if we weren't added to this hash in the first place + } + + // Mark the queue as being recyclable + producer->inactive.store(true, std::memory_order_release); + } + + static void implicit_producer_thread_exited_callback(void* userData) + { + auto producer = static_cast<ImplicitProducer*>(userData); + auto queue = producer->parent; + queue->implicit_producer_thread_exited(producer); + } +#endif + + ////////////////////////////////// + // Utility functions + ////////////////////////////////// + + template<typename TAlign> + static inline void* aligned_malloc(size_t size) + { + MOODYCAMEL_CONSTEXPR_IF (std::alignment_of<TAlign>::value <= std::alignment_of<details::max_align_t>::value) + return (Traits::malloc)(size); + else { + size_t alignment = std::alignment_of<TAlign>::value; + void* raw = (Traits::malloc)(size + alignment - 1 + sizeof(void*)); + if (!raw) + return nullptr; + char* ptr = details::align_for<TAlign>(reinterpret_cast<char*>(raw) + sizeof(void*)); + *(reinterpret_cast<void**>(ptr) - 1) = raw; + return ptr; + } + } + + template<typename TAlign> + static inline void aligned_free(void* ptr) + { + MOODYCAMEL_CONSTEXPR_IF (std::alignment_of<TAlign>::value <= std::alignment_of<details::max_align_t>::value) + return (Traits::free)(ptr); + else + (Traits::free)(ptr ? *(reinterpret_cast<void**>(ptr) - 1) : nullptr); + } + + template<typename U> + static inline U* create_array(size_t count) + { + assert(count > 0); + U* p = static_cast<U*>(aligned_malloc<U>(sizeof(U) * count)); + if (p == nullptr) + return nullptr; + + for (size_t i = 0; i != count; ++i) + new (p + i) U(); + return p; + } + + template<typename U> + static inline void destroy_array(U* p, size_t count) + { + if (p != nullptr) { + assert(count > 0); + for (size_t i = count; i != 0; ) + (p + --i)->~U(); + } + aligned_free<U>(p); + } + + template<typename U> + static inline U* create() + { + void* p = aligned_malloc<U>(sizeof(U)); + return p != nullptr ? new (p) U : nullptr; + } + + template<typename U, typename A1> + static inline U* create(A1&& a1) + { + void* p = aligned_malloc<U>(sizeof(U)); + return p != nullptr ? new (p) U(std::forward<A1>(a1)) : nullptr; + } + + template<typename U> + static inline void destroy(U* p) + { + if (p != nullptr) + p->~U(); + aligned_free<U>(p); + } + +private: + std::atomic<ProducerBase*> producerListTail; + std::atomic<std::uint32_t> producerCount; + + std::atomic<size_t> initialBlockPoolIndex; + Block* initialBlockPool; + size_t initialBlockPoolSize; + +#ifndef MCDBGQ_USEDEBUGFREELIST + FreeList<Block> freeList; +#else + debug::DebugFreeList<Block> freeList; +#endif + + std::atomic<ImplicitProducerHash*> implicitProducerHash; + std::atomic<size_t> implicitProducerHashCount; // Number of slots logically used + ImplicitProducerHash initialImplicitProducerHash; + std::array<ImplicitProducerKVP, INITIAL_IMPLICIT_PRODUCER_HASH_SIZE> initialImplicitProducerHashEntries; + std::atomic_flag implicitProducerHashResizeInProgress; + + std::atomic<std::uint32_t> nextExplicitConsumerId; + std::atomic<std::uint32_t> globalExplicitConsumerOffset; + +#ifdef MCDBGQ_NOLOCKFREE_IMPLICITPRODHASH + debug::DebugMutex implicitProdMutex; +#endif + +#ifdef MOODYCAMEL_QUEUE_INTERNAL_DEBUG + std::atomic<ExplicitProducer*> explicitProducers; + std::atomic<ImplicitProducer*> implicitProducers; +#endif +}; + + +template<typename T, typename Traits> +ProducerToken::ProducerToken(ConcurrentQueue<T, Traits>& queue) + : producer(queue.recycle_or_create_producer(true)) +{ + if (producer != nullptr) { + producer->token = this; + } +} + +template<typename T, typename Traits> +ProducerToken::ProducerToken(BlockingConcurrentQueue<T, Traits>& queue) + : producer(reinterpret_cast<ConcurrentQueue<T, Traits>*>(&queue)->recycle_or_create_producer(true)) +{ + if (producer != nullptr) { + producer->token = this; + } +} + +template<typename T, typename Traits> +ConsumerToken::ConsumerToken(ConcurrentQueue<T, Traits>& queue) + : itemsConsumedFromCurrent(0), currentProducer(nullptr), desiredProducer(nullptr) +{ + initialOffset = queue.nextExplicitConsumerId.fetch_add(1, std::memory_order_release); + lastKnownGlobalOffset = static_cast<std::uint32_t>(-1); +} + +template<typename T, typename Traits> +ConsumerToken::ConsumerToken(BlockingConcurrentQueue<T, Traits>& queue) + : itemsConsumedFromCurrent(0), currentProducer(nullptr), desiredProducer(nullptr) +{ + initialOffset = reinterpret_cast<ConcurrentQueue<T, Traits>*>(&queue)->nextExplicitConsumerId.fetch_add(1, std::memory_order_release); + lastKnownGlobalOffset = static_cast<std::uint32_t>(-1); +} + +template<typename T, typename Traits> +inline void swap(ConcurrentQueue<T, Traits>& a, ConcurrentQueue<T, Traits>& b) MOODYCAMEL_NOEXCEPT +{ + a.swap(b); +} + +inline void swap(ProducerToken& a, ProducerToken& b) MOODYCAMEL_NOEXCEPT +{ + a.swap(b); +} + +inline void swap(ConsumerToken& a, ConsumerToken& b) MOODYCAMEL_NOEXCEPT +{ + a.swap(b); +} + +template<typename T, typename Traits> +inline void swap(typename ConcurrentQueue<T, Traits>::ImplicitProducerKVP& a, typename ConcurrentQueue<T, Traits>::ImplicitProducerKVP& b) MOODYCAMEL_NOEXCEPT +{ + a.swap(b); +} + +} + +#if defined(_MSC_VER) && (!defined(_HAS_CXX17) || !_HAS_CXX17) +#pragma warning(pop) +#endif + +#if defined(__GNUC__) && !defined(__INTEL_COMPILER) +#pragma GCC diagnostic pop +#endif |