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>

1 files changed, 11 insertions, 39 deletions

diff --git a/trace/simple.c b/trace/simple.c
index a8f923c82e..11ad030937 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)
@@ -383,11 +364,7 @@ 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);
@@ -402,11 +379,6 @@ bool st_init(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");