1 files changed, 154 insertions, 0 deletions
diff --git a/include/qemu/coroutine-core.h b/include/qemu/coroutine-core.h
new file mode 100644
index 0000000000..230bb56517
--- /dev/null
+++ b/include/qemu/coroutine-core.h
@@ -0,0 +1,154 @@
+/*
+ * QEMU coroutine implementation
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
+ *  Kevin Wolf         <kwolf@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_COROUTINE_CORE_H
+#define QEMU_COROUTINE_CORE_H
+
+/**
+ * Coroutines are a mechanism for stack switching and can be used for
+ * cooperative userspace threading.  These functions provide a simple but
+ * useful flavor of coroutines that is suitable for writing sequential code,
+ * rather than callbacks, for operations that need to give up control while
+ * waiting for events to complete.
+ *
+ * These functions are re-entrant and may be used outside the global mutex.
+ *
+ * Functions that execute in coroutine context cannot be called
+ * directly from normal functions.  Use @coroutine_fn to mark such
+ * functions.  For example:
+ *
+ *   static void coroutine_fn foo(void) {
+ *       ....
+ *   }
+ *
+ * In the future it would be nice to have the compiler or a static
+ * checker catch misuse of such functions.  This annotation might make
+ * it possible and in the meantime it serves as documentation.
+ */
+
+/**
+ * Mark a function that executes in coroutine context
+ *
+ *
+ * Functions that execute in coroutine context cannot be called
+ * directly from normal functions.  Use @coroutine_fn to mark such
+ * functions.  For example:
+ *
+ *   static void coroutine_fn foo(void) {
+ *       ....
+ *   }
+ *
+ * In the future it would be nice to have the compiler or a static
+ * checker catch misuse of such functions.  This annotation might make
+ * it possible and in the meantime it serves as documentation.
+ */
+
+typedef struct Coroutine Coroutine;
+typedef struct CoMutex CoMutex;
+
+/**
+ * Coroutine entry point
+ *
+ * When the coroutine is entered for the first time, opaque is passed in as an
+ * argument.
+ *
+ * When this function returns, the coroutine is destroyed automatically and
+ * execution continues in the caller who last entered the coroutine.
+ */
+typedef void coroutine_fn CoroutineEntry(void *opaque);
+
+/**
+ * Create a new coroutine
+ *
+ * Use qemu_coroutine_enter() to actually transfer control to the coroutine.
+ * The opaque argument is passed as the argument to the entry point.
+ */
+Coroutine *qemu_coroutine_create(CoroutineEntry *entry, void *opaque);
+
+/**
+ * Transfer control to a coroutine
+ */
+void qemu_coroutine_enter(Coroutine *coroutine);
+
+/**
+ * Transfer control to a coroutine if it's not active (i.e. part of the call
+ * stack of the running coroutine). Otherwise, do nothing.
+ */
+void qemu_coroutine_enter_if_inactive(Coroutine *co);
+
+/**
+ * Transfer control to a coroutine and associate it with ctx
+ */
+void qemu_aio_coroutine_enter(AioContext *ctx, Coroutine *co);
+
+/**
+ * Transfer control back to a coroutine's caller
+ *
+ * This function does not return until the coroutine is re-entered using
+ * qemu_coroutine_enter().
+ */
+void coroutine_fn qemu_coroutine_yield(void);
+
+/**
+ * Get the AioContext of the given coroutine
+ */
+AioContext *qemu_coroutine_get_aio_context(Coroutine *co);
+
+/**
+ * Get the currently executing coroutine
+ */
+Coroutine *qemu_coroutine_self(void);
+
+/**
+ * Return whether or not currently inside a coroutine
+ *
+ * This can be used to write functions that work both when in coroutine context
+ * and when not in coroutine context.  Note that such functions cannot use the
+ * coroutine_fn annotation since they work outside coroutine context.
+ */
+bool qemu_in_coroutine(void);
+
+/**
+ * Return true if the coroutine is currently entered
+ *
+ * A coroutine is "entered" if it has not yielded from the current
+ * qemu_coroutine_enter() call used to run it.  This does not mean that the
+ * coroutine is currently executing code since it may have transferred control
+ * to another coroutine using qemu_coroutine_enter().
+ *
+ * When several coroutines enter each other there may be no way to know which
+ * ones have already been entered.  In such situations this function can be
+ * used to avoid recursively entering coroutines.
+ */
+bool qemu_coroutine_entered(Coroutine *co);
+
+/**
+ * Initialises a CoMutex. This must be called before any other operation is used
+ * on the CoMutex.
+ */
+void qemu_co_mutex_init(CoMutex *mutex);
+
+/**
+ * Locks the mutex. If the lock cannot be taken immediately, control is
+ * transferred to the caller of the current coroutine.
+ */
+void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex);
+
+/**
+ * Unlocks the mutex and schedules the next coroutine that was waiting for this
+ * lock to be run.
+ */
+void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex);
+
+#endif