Merge pull request #3 from ckrinitsin/shm

Shared Memory Buffer

2 files changed, 100 insertions, 22 deletions

diff --git a/src/server/main.cpp b/src/server/main.cpp
index b2f8bed..424326f 100644
--- a/src/server/main.cpp
+++ b/src/server/main.cpp
@@ -1,8 +1,9 @@
 #include <cstdint>
+#include <iostream>
 #include <stdexcept>
 #include <string>
 
-#include "hashtable.h"
+#include "shared_memory_server.h"
 
 int main(int argc, char* argv[])
 {
@@ -18,29 +19,10 @@ int main(int argc, char* argv[])
         std::cout << "Invalid argument" << '\n';
         return 1;
     }
-  
-    HashTable<int, std::string> hash_table { size };
 
-    std::cout << "Add various kv-pairs" << '\n';
-    hash_table.insert(1, "1");
-    hash_table.insert(2, "2");
-    hash_table.insert(3, "3");
-    hash_table.insert(4, "4");
-    hash_table.insert(5, "5");
-    hash_table.insert(6, "6");
-    hash_table.insert(7, "7");
+    SharedMemoryServer<int, std::string> shm(size);
 
-    hash_table.print();
-
-    std::cout << '\n';
-
-    std::cout << "Value for key 8: " << hash_table.get(8).value_or("Key not found!") << '\n';
-    std::cout << "Value for key 4: " << hash_table.get(4).value_or("Key not found!") << '\n';
-
-    std::cout << '\n';
-    std::cout << "Remove pair with key 5" << '\n';
-    hash_table.remove(5);
-    hash_table.print();
+    shm.process_requests();
 
     return 0;
 }
diff --git a/src/server/shared_memory_server.h b/src/server/shared_memory_server.h
new file mode 100644
index 0000000..74abedf
--- /dev/null
+++ b/src/server/shared_memory_server.h
@@ -0,0 +1,96 @@
+#pragma once
+
+#include "hashtable.h"
+#include "shared_memory.h"
+#include <cstring>
+#include <fcntl.h>
+#include <optional>
+#include <sys/mman.h>
+#include <unistd.h>
+
+template <typename K, typename V>
+class SharedMemoryServer {
+public:
+    SharedMemoryServer(size_t size)
+        : hash_table(size)
+    {
+        shm_fd = shm_open(SHM_NAME, O_CREAT | O_RDWR, 0666);
+
+        ftruncate(shm_fd, sizeof(SharedMemory));
+
+        shared_memory = (SharedMemory*)
+            mmap(0, sizeof(SharedMemory), PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
+
+        shared_memory->tail = shared_memory->head = 0;
+
+        pthread_mutexattr_t mutex_attr;
+        pthread_condattr_t cond_attr;
+        pthread_mutexattr_init(&mutex_attr);
+        pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED);
+        pthread_condattr_init(&cond_attr);
+        pthread_condattr_setpshared(&cond_attr, PTHREAD_PROCESS_SHARED);
+
+        pthread_mutex_init(&shared_memory->mutex, &mutex_attr);
+        pthread_cond_init(&shared_memory->cond_var, &cond_attr);
+    }
+
+    ~SharedMemoryServer()
+    {
+        munmap(shared_memory, sizeof(SharedMemory));
+        close(shm_fd);
+        shm_unlink(SHM_NAME);
+    }
+
+    void process_requests()
+    {
+        while (true) {
+            pthread_mutex_lock(&shared_memory->mutex);
+
+            if (shared_memory->tail == shared_memory->head && !shared_memory->full) {
+                pthread_cond_wait(&shared_memory->cond_var, &shared_memory->mutex);
+            }
+
+            Request* request = &shared_memory->request[shared_memory->tail];
+
+            K key = deserialize<K>(request->key);
+            V value = deserialize<V>(request->value);
+
+            switch (request->type) {
+            case INSERT:
+                std::cout << "Inserting" << '\n';
+                hash_table.insert(key, value);
+                break;
+            case GET: {
+                std::cout << "Getting" << '\n';
+                hash_table.insert(key, value);
+                std::optional<V> result = hash_table.get(key);
+                if (result.has_value()) {
+                    std::string response = serialize<V>(result.value());
+                    strncpy(request->response, response.c_str(), MAX_VALUE_SIZE);
+                    pthread_cond_signal(&shared_memory->cond_var);
+                }
+                break;
+            }
+            case DELETE:
+                std::cout << "Deleting" << '\n';
+                hash_table.remove(key);
+                break;
+            case PRINT:
+                std::cout << "Printing" << '\n';
+                hash_table.print();
+                break;
+            default:
+                break;
+            }
+            shared_memory->tail = (1 + shared_memory->tail) % QUEUE_SIZE;
+            shared_memory->full = false;
+            pthread_mutex_unlock(&shared_memory->mutex);
+        }
+    }
+
+private:
+    HashTable<K, V> hash_table;
+
+    int shm_fd;
+    SharedMemory* shared_memory;
+};