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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 "block/coroutine_int.h"
typedef struct {
Coroutine base;
GThread *thread;
bool runnable;
bool free_on_thread_exit;
CoroutineAction action;
} CoroutineGThread;
static GStaticMutex coroutine_lock = G_STATIC_MUTEX_INIT;
/* 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)
/* Default zero-initialisation is sufficient for 2.31+ GCond */
static GCond the_coroutine_cond;
static GCond *coroutine_cond = &the_coroutine_cond;
static inline void init_coroutine_cond(void)
{
}
/* 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 GCond *coroutine_cond;
static inline void init_coroutine_cond(void)
{
coroutine_cond = g_cond_new();
}
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 (!g_thread_supported()) {
#if !GLIB_CHECK_VERSION(2, 31, 0)
g_thread_init(NULL);
#else
fprintf(stderr, "glib threading failed to initialize.\n");
exit(1);
#endif
}
init_coroutine_cond();
}
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;
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_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 = 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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