[babl] Don't create a mutexattr for each mutex

[Mukund Sivaraman <muks src gnome org>]

commit f0ae3c4c7b4b33258cb797120892646342add9b7
Author: Mukund Sivaraman <muks banu com>
Date:   Wed Apr 22 13:40:06 2015 +0530

    Don't create a mutexattr for each mutex

 babl/babl-mutex.c |   29 +++++++++++++++++++++++------
 1 files changed, 23 insertions(+), 6 deletions(-)
---
diff --git a/babl/babl-mutex.c b/babl/babl-mutex.c
index 708c54a..4fa5f29 100644
--- a/babl/babl-mutex.c
+++ b/babl/babl-mutex.c
@@ -21,6 +21,28 @@
 
 #include <stdlib.h>
 
+#ifndef _WIN32
+
+static const pthread_mutexattr_t *
+get_mutex_attr (void)
+{
+  static pthread_mutexattr_t mutexattr;
+  static int initialized = 0;
+
+  if (!initialized)
+    {
+      /* On some platforms, this will keep an allocation till process
+         termination, but it isn't a growing leak. */
+      pthread_mutexattr_init (&mutexattr);
+      pthread_mutexattr_settype (&mutexattr, PTHREAD_MUTEX_RECURSIVE);
+      initialized = 1;
+    }
+
+  return &mutexattr;
+}
+
+#endif
+
 BablMutex  *
 babl_mutex_new (void)
 {
@@ -28,12 +50,7 @@ babl_mutex_new (void)
 #ifdef _WIN32
   InitializeCriticalSection (mutex);
 #else
-  pthread_mutexattr_t mutexattr;
-
-  pthread_mutexattr_init (&mutexattr);
-  pthread_mutexattr_settype (&mutexattr, PTHREAD_MUTEX_RECURSIVE);
-  pthread_mutex_init (mutex, &mutexattr);
-  pthread_mutexattr_destroy (&mutexattr);
+  pthread_mutex_init (mutex, get_mutex_attr ());
 #endif
   return mutex;
 }