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-rw-r--r--util/coroutine-gthread.c198
1 files changed, 198 insertions, 0 deletions
diff --git a/util/coroutine-gthread.c b/util/coroutine-gthread.c
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+++ b/util/coroutine-gthread.c
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+/*
+ * GThread coroutine initialization code
+ *
+ * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
+ * Copyright (C) 2011 Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.0 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <glib.h>
+#include "qemu-common.h"
+#include "qemu/coroutine_int.h"
+
+typedef struct {
+ Coroutine base;
+ GThread *thread;
+ bool runnable;
+ bool free_on_thread_exit;
+ CoroutineAction action;
+} CoroutineGThread;
+
+static CompatGMutex coroutine_lock;
+static CompatGCond coroutine_cond;
+
+/* GLib 2.31 and beyond deprecated various parts of the thread API,
+ * but the new interfaces are not available in older GLib versions
+ * so we have to cope with both.
+ */
+#if GLIB_CHECK_VERSION(2, 31, 0)
+/* Awkwardly, the GPrivate API doesn't provide a way to update the
+ * GDestroyNotify handler for the coroutine key dynamically. So instead
+ * we track whether or not the CoroutineGThread should be freed on
+ * thread exit / coroutine key update using the free_on_thread_exit
+ * field.
+ */
+static void coroutine_destroy_notify(gpointer data)
+{
+ CoroutineGThread *co = data;
+ if (co && co->free_on_thread_exit) {
+ g_free(co);
+ }
+}
+
+static GPrivate coroutine_key = G_PRIVATE_INIT(coroutine_destroy_notify);
+
+static inline CoroutineGThread *get_coroutine_key(void)
+{
+ return g_private_get(&coroutine_key);
+}
+
+static inline void set_coroutine_key(CoroutineGThread *co,
+ bool free_on_thread_exit)
+{
+ /* Unlike g_static_private_set() this does not call the GDestroyNotify
+ * if the previous value of the key was NULL. Fortunately we only need
+ * the GDestroyNotify in the non-NULL key case.
+ */
+ co->free_on_thread_exit = free_on_thread_exit;
+ g_private_replace(&coroutine_key, co);
+}
+
+static inline GThread *create_thread(GThreadFunc func, gpointer data)
+{
+ return g_thread_new("coroutine", func, data);
+}
+
+#else
+
+/* Handle older GLib versions */
+
+static GStaticPrivate coroutine_key = G_STATIC_PRIVATE_INIT;
+
+static inline CoroutineGThread *get_coroutine_key(void)
+{
+ return g_static_private_get(&coroutine_key);
+}
+
+static inline void set_coroutine_key(CoroutineGThread *co,
+ bool free_on_thread_exit)
+{
+ g_static_private_set(&coroutine_key, co,
+ free_on_thread_exit ? (GDestroyNotify)g_free : NULL);
+}
+
+static inline GThread *create_thread(GThreadFunc func, gpointer data)
+{
+ return g_thread_create_full(func, data, 0, TRUE, TRUE,
+ G_THREAD_PRIORITY_NORMAL, NULL);
+}
+
+#endif
+
+
+static void __attribute__((constructor)) coroutine_init(void)
+{
+#if !GLIB_CHECK_VERSION(2, 31, 0)
+ if (!g_thread_supported()) {
+ g_thread_init(NULL);
+ }
+#endif
+}
+
+static void coroutine_wait_runnable_locked(CoroutineGThread *co)
+{
+ while (!co->runnable) {
+ g_cond_wait(&coroutine_cond, &coroutine_lock);
+ }
+}
+
+static void coroutine_wait_runnable(CoroutineGThread *co)
+{
+ g_mutex_lock(&coroutine_lock);
+ coroutine_wait_runnable_locked(co);
+ g_mutex_unlock(&coroutine_lock);
+}
+
+static gpointer coroutine_thread(gpointer opaque)
+{
+ CoroutineGThread *co = opaque;
+
+ set_coroutine_key(co, false);
+ coroutine_wait_runnable(co);
+ co->base.entry(co->base.entry_arg);
+ qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
+ return NULL;
+}
+
+Coroutine *qemu_coroutine_new(void)
+{
+ CoroutineGThread *co;
+
+ co = g_malloc0(sizeof(*co));
+ co->thread = create_thread(coroutine_thread, co);
+ if (!co->thread) {
+ g_free(co);
+ return NULL;
+ }
+ return &co->base;
+}
+
+void qemu_coroutine_delete(Coroutine *co_)
+{
+ CoroutineGThread *co = DO_UPCAST(CoroutineGThread, base, co_);
+
+ g_thread_join(co->thread);
+ g_free(co);
+}
+
+CoroutineAction qemu_coroutine_switch(Coroutine *from_,
+ Coroutine *to_,
+ CoroutineAction action)
+{
+ CoroutineGThread *from = DO_UPCAST(CoroutineGThread, base, from_);
+ CoroutineGThread *to = DO_UPCAST(CoroutineGThread, base, to_);
+
+ g_mutex_lock(&coroutine_lock);
+ from->runnable = false;
+ from->action = action;
+ to->runnable = true;
+ to->action = action;
+ g_cond_broadcast(&coroutine_cond);
+
+ if (action != COROUTINE_TERMINATE) {
+ coroutine_wait_runnable_locked(from);
+ }
+ g_mutex_unlock(&coroutine_lock);
+ return from->action;
+}
+
+Coroutine *qemu_coroutine_self(void)
+{
+ CoroutineGThread *co = get_coroutine_key();
+ if (!co) {
+ co = g_malloc0(sizeof(*co));
+ co->runnable = true;
+ set_coroutine_key(co, true);
+ }
+
+ return &co->base;
+}
+
+bool qemu_in_coroutine(void)
+{
+ CoroutineGThread *co = get_coroutine_key();
+
+ return co && co->base.caller;
+}
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