coroutine: implement coroutines using gthread
On platforms that don't support makecontext(3) use gthread based
coroutine implementation.
Darwin has makecontext(3) but getcontext(3) is stubbed out to return
ENOTSUP. Andreas Färber <[email protected]> debugged this and
contributed the ./configure test which solves the issue for Darwin/ppc64
(and ppc) v10.5.
[Original patch by Aneesh, made consistent with coroutine-ucontext.c and
switched to GStaticPrivate by Stefan. Tested on Linux and OpenBSD.]
Signed-off-by: Aneesh Kumar K.V <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>
diff --git a/coroutine-gthread.c b/coroutine-gthread.c
new file mode 100644
index 0000000..f09877e
--- /dev/null
+++ b/coroutine-gthread.c
@@ -0,0 +1,131 @@
+/*
+ * GThread coroutine initialization code
+ *
+ * Copyright (C) 2006 Anthony Liguori <[email protected]>
+ * Copyright (C) 2011 Aneesh Kumar K.V <[email protected]>
+ *
+ * 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;
+ CoroutineAction action;
+} CoroutineGThread;
+
+static GCond *coroutine_cond;
+static GStaticMutex coroutine_lock = G_STATIC_MUTEX_INIT;
+static GStaticPrivate coroutine_key = G_STATIC_PRIVATE_INIT;
+
+static void __attribute__((constructor)) coroutine_init(void)
+{
+ if (!g_thread_supported()) {
+ g_thread_init(NULL);
+ }
+
+ coroutine_cond = g_cond_new();
+}
+
+static void coroutine_wait_runnable_locked(CoroutineGThread *co)
+{
+ while (!co->runnable) {
+ g_cond_wait(coroutine_cond, g_static_mutex_get_mutex(&coroutine_lock));
+ }
+}
+
+static void coroutine_wait_runnable(CoroutineGThread *co)
+{
+ g_static_mutex_lock(&coroutine_lock);
+ coroutine_wait_runnable_locked(co);
+ g_static_mutex_unlock(&coroutine_lock);
+}
+
+static gpointer coroutine_thread(gpointer opaque)
+{
+ CoroutineGThread *co = opaque;
+
+ g_static_private_set(&coroutine_key, co, NULL);
+ 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 = qemu_mallocz(sizeof(*co));
+ co->thread = g_thread_create_full(coroutine_thread, co, 0, TRUE, TRUE,
+ G_THREAD_PRIORITY_NORMAL, NULL);
+ if (!co->thread) {
+ qemu_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);
+ qemu_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_static_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_static_mutex_unlock(&coroutine_lock);
+ return from->action;
+}
+
+Coroutine *qemu_coroutine_self(void)
+{
+ CoroutineGThread *co = g_static_private_get(&coroutine_key);
+
+ if (!co) {
+ co = qemu_mallocz(sizeof(*co));
+ co->runnable = true;
+ g_static_private_set(&coroutine_key, co, (GDestroyNotify)qemu_free);
+ }
+
+ return &co->base;
+}
+
+bool qemu_in_coroutine(void)
+{
+ CoroutineGThread *co = g_static_private_get(&coroutine_key);
+
+ return co && co->base.caller;
+}
