From 57a1d211179279727d5afa21a7feba2d249d6867 Mon Sep 17 00:00:00 2001
From: Michael Tokarev <mjt@tls.msk.ru>
Date: Thu, 8 May 2014 12:30:46 +0400
Subject: [PATCH] glib-compat.h: add new thread API emulation on top of
pre-2.31 API
Thread API changed in glib-2.31 significantly. Before that version,
conditionals and mutexes were only allocated dynamically, using
_new()/_free() interface. in 2.31 and up, they're allocated statically
as regular variables, and old interface is deprecated.
(Note: glib docs says the new interface is available since version
2.32, but it was actually introduced in version 2.31).
Create the new interface using old primitives, by providing non-opaque
definitions of the base types (GCond and GMutex) using GOnces.
Replace #ifdeffery around GCond and GMutex in trace/simple.c and
coroutine-gthread.c too because it does not work anymore with the new
glib-compat.h.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[Use GOnce to support lazy initialization; introduce CompatGMutex
and CompatGCond. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 86946a2d835614050b90bc8e5c82982fe45deff2)
---
coroutine-gthread.c | 29 ++++--------
include/glib-compat.h | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++
trace/simple.c | 50 +++++----------------
3 files changed, 138 insertions(+), 60 deletions(-)
diff --git a/coroutine-gthread.c b/coroutine-gthread.c
index a61efe0..6bd6d6b 100644
--- a/coroutine-gthread.c
+++ b/coroutine-gthread.c
@@ -30,20 +30,14 @@ typedef struct {
CoroutineAction action;
} CoroutineGThread;
-static GStaticMutex coroutine_lock = G_STATIC_MUTEX_INIT;
+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)
-/* 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
@@ -84,11 +78,6 @@ static inline GThread *create_thread(GThreadFunc func, gpointer 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;
@@ -120,22 +109,20 @@ static void __attribute__((constructor)) coroutine_init(void)
g_thread_init(NULL);
}
#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));
+ g_cond_wait(&coroutine_cond, &coroutine_lock);
}
}
static void coroutine_wait_runnable(CoroutineGThread *co)
{
- g_static_mutex_lock(&coroutine_lock);
+ g_mutex_lock(&coroutine_lock);
coroutine_wait_runnable_locked(co);
- g_static_mutex_unlock(&coroutine_lock);
+ g_mutex_unlock(&coroutine_lock);
}
static gpointer coroutine_thread(gpointer opaque)
@@ -177,17 +164,17 @@ CoroutineAction qemu_coroutine_switch(Coroutine *from_,
CoroutineGThread *from = DO_UPCAST(CoroutineGThread, base, from_);
CoroutineGThread *to = DO_UPCAST(CoroutineGThread, base, to_);
- g_static_mutex_lock(&coroutine_lock);
+ g_mutex_lock(&coroutine_lock);
from->runnable = false;
from->action = action;
to->runnable = true;
to->action = action;
- g_cond_broadcast(coroutine_cond);
+ g_cond_broadcast(&coroutine_cond);
if (action != COROUTINE_TERMINATE) {
coroutine_wait_runnable_locked(from);
}
- g_static_mutex_unlock(&coroutine_lock);
+ g_mutex_unlock(&coroutine_lock);
return from->action;
}
diff --git a/include/glib-compat.h b/include/glib-compat.h
index 1280fb2..4ae0671 100644
--- a/include/glib-compat.h
+++ b/include/glib-compat.h
@@ -5,6 +5,8 @@
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
+ * Michael Tokarev <mjt@tls.msk.ru>
+ * Paolo Bonzini <pbonzini@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
@@ -43,4 +45,121 @@ static inline gint g_poll(GPollFD *fds, guint nfds, gint timeout)
}
#endif
+#if !GLIB_CHECK_VERSION(2, 31, 0)
+/* before glib-2.31, GMutex and GCond was dynamic-only (there was a separate
+ * GStaticMutex, but it didn't work with condition variables).
+ *
+ * Our implementation uses GOnce to fake a static implementation that does
+ * not require separate initialization.
+ * We need to rename the types to avoid passing our CompatGMutex/CompatGCond
+ * by mistake to a function that expects GMutex/GCond. However, for ease
+ * of use we keep the GLib function names. GLib uses macros for the
+ * implementation, we use inline functions instead and undefine the macros.
+ */
+
+typedef struct CompatGMutex {
+ GOnce once;
+} CompatGMutex;
+
+typedef struct CompatGCond {
+ GOnce once;
+} CompatGCond;
+
+static inline gpointer do_g_mutex_new(gpointer unused)
+{
+ return (gpointer) g_mutex_new();
+}
+
+static inline void g_mutex_init(CompatGMutex *mutex)
+{
+ mutex->once = (GOnce) G_ONCE_INIT;
+}
+
+static inline void g_mutex_clear(CompatGMutex *mutex)
+{
+ assert(mutex->once.status != G_ONCE_STATUS_PROGRESS);
+ if (mutex->once.retval) {
+ g_mutex_free((GMutex *) mutex->once.retval);
+ }
+ mutex->once = (GOnce) G_ONCE_INIT;
+}
+
+static inline void (g_mutex_lock)(CompatGMutex *mutex)
+{
+ g_once(&mutex->once, do_g_mutex_new, NULL);
+ g_mutex_lock((GMutex *) mutex->once.retval);
+}
+#undef g_mutex_lock
+
+static inline gboolean (g_mutex_trylock)(CompatGMutex *mutex)
+{
+ g_once(&mutex->once, do_g_mutex_new, NULL);
+ return g_mutex_trylock((GMutex *) mutex->once.retval);
+}
+#undef g_mutex_trylock
+
+
+static inline void (g_mutex_unlock)(CompatGMutex *mutex)
+{
+ g_mutex_unlock((GMutex *) mutex->once.retval);
+}
+#undef g_mutex_unlock
+
+static inline gpointer do_g_cond_new(gpointer unused)
+{
+ return (gpointer) g_cond_new();
+}
+
+static inline void g_cond_init(CompatGCond *cond)
+{
+ cond->once = (GOnce) G_ONCE_INIT;
+}
+
+static inline void g_cond_clear(CompatGCond *cond)
+{
+ assert(cond->once.status != G_ONCE_STATUS_PROGRESS);
+ if (cond->once.retval) {
+ g_cond_free((GCond *) cond->once.retval);
+ }
+ cond->once = (GOnce) G_ONCE_INIT;
+}
+
+static inline void (g_cond_wait)(CompatGCond *cond, CompatGMutex *mutex)
+{
+ assert(mutex->once.status != G_ONCE_STATUS_PROGRESS);
+ g_once(&cond->once, do_g_cond_new, NULL);
+ g_cond_wait((GCond *) cond->once.retval, (GMutex *) mutex->once.retval);
+}
+#undef g_cond_wait
+
+static inline void (g_cond_broadcast)(CompatGCond *cond)
+{
+ g_once(&cond->once, do_g_cond_new, NULL);
+ g_cond_broadcast((GCond *) cond->once.retval);
+}
+#undef g_cond_broadcast
+
+static inline void (g_cond_signal)(CompatGCond *cond)
+{
+ g_once(&cond->once, do_g_cond_new, NULL);
+ g_cond_signal((GCond *) cond->once.retval);
+}
+#undef g_cond_signal
+
+
+/* before 2.31 there was no g_thread_new() */
+static inline GThread *g_thread_new(const char *name,
+ GThreadFunc func, gpointer data)
+{
+ GThread *thread = g_thread_create(func, data, TRUE, NULL);
+ if (!thread) {
+ g_error("creating thread");
+ }
+ return thread;
+}
+#else
+#define CompatGMutex GMutex
+#define CompatGCond GCond
+#endif /* glib 2.31 */
+
#endif
diff --git a/trace/simple.c b/trace/simple.c
index 1584bf7..8fc96fe 100644
--- a/trace/simple.c
+++ b/trace/simple.c
@@ -40,28 +40,9 @@
* Trace records are written out by a dedicated thread. The thread waits for
* records to become available, writes them out, and then waits again.
*/
-#if GLIB_CHECK_VERSION(2, 32, 0)
-static GMutex trace_lock;
-#define lock_trace_lock() g_mutex_lock(&trace_lock)
-#define unlock_trace_lock() g_mutex_unlock(&trace_lock)
-#define get_trace_lock_mutex() (&trace_lock)
-#else
-static GStaticMutex trace_lock = G_STATIC_MUTEX_INIT;
-#define lock_trace_lock() g_static_mutex_lock(&trace_lock)
-#define unlock_trace_lock() g_static_mutex_unlock(&trace_lock)
-#define get_trace_lock_mutex() g_static_mutex_get_mutex(&trace_lock)
-#endif
-
-/* g_cond_new() was deprecated in glib 2.31 but we still need to support it */
-#if GLIB_CHECK_VERSION(2, 31, 0)
-static GCond the_trace_available_cond;
-static GCond the_trace_empty_cond;
-static GCond *trace_available_cond = &the_trace_available_cond;
-static GCond *trace_empty_cond = &the_trace_empty_cond;
-#else
-static GCond *trace_available_cond;
-static GCond *trace_empty_cond;
-#endif
+static CompatGMutex trace_lock;
+static CompatGCond trace_available_cond;
+static CompatGCond trace_empty_cond;
static bool trace_available;
static bool trace_writeout_enabled;
@@ -151,26 +132,26 @@ static bool get_trace_record(unsigned int idx, TraceRecord **recordptr)
*/
static void flush_trace_file(bool wait)
{
- lock_trace_lock();
+ g_mutex_lock(&trace_lock);
trace_available = true;
- g_cond_signal(trace_available_cond);
+ g_cond_signal(&trace_available_cond);
if (wait) {
- g_cond_wait(trace_empty_cond, get_trace_lock_mutex());
+ g_cond_wait(&trace_empty_cond, &trace_lock);
}
- unlock_trace_lock();
+ g_mutex_unlock(&trace_lock);
}
static void wait_for_trace_records_available(void)
{
- lock_trace_lock();
+ g_mutex_lock(&trace_lock);
while (!(trace_available && trace_writeout_enabled)) {
- g_cond_signal(trace_empty_cond);
- g_cond_wait(trace_available_cond, get_trace_lock_mutex());
+ g_cond_signal(&trace_empty_cond);
+ g_cond_wait(&trace_available_cond, &trace_lock);
}
trace_available = false;
- unlock_trace_lock();
+ g_mutex_unlock(&trace_lock);
}
static gpointer writeout_thread(gpointer opaque)
@@ -399,11 +380,7 @@ static GThread *trace_thread_create(GThreadFunc fn)
pthread_sigmask(SIG_SETMASK, &set, &oldset);
#endif
-#if GLIB_CHECK_VERSION(2, 31, 0)
thread = g_thread_new("trace-thread", fn, NULL);
-#else
- thread = g_thread_create(fn, NULL, FALSE, NULL);
-#endif
#ifndef _WIN32
pthread_sigmask(SIG_SETMASK, &oldset, NULL);
@@ -418,11 +395,6 @@ bool trace_backend_init(const char *events, const char *file)
trace_pid = getpid();
-#if !GLIB_CHECK_VERSION(2, 31, 0)
- trace_available_cond = g_cond_new();
- trace_empty_cond = g_cond_new();
-#endif
-
thread = trace_thread_create(writeout_thread);
if (!thread) {
fprintf(stderr, "warning: unable to initialize simple trace backend\n");