make evthread_use_pthreads a MT-Safe function

diff --git a/evthread_pthread.c b/evthread_pthread.c
index 94e7da958619a79279bf367f4ec57486761f970b..56c3b86ea8dd91b4cf8edf9a2efe7b13276cc3f4 100644 (file)
--- a/evthread_pthread.c
+++ b/evthread_pthread.c
@@ -42,6 +42,9 @@ struct event_base;
 static pthread_mutexattr_t attr_default;
 static pthread_mutexattr_t attr_recursive;
 
+static pthread_mutex_t once_init_lock = PTHREAD_MUTEX_INITIALIZER;
+static int once_init = 0;
+
 static void *
 evthread_posix_lock_alloc(unsigned locktype)
 {
@@ -180,31 +183,42 @@ evthread_use_pthreads_with_flags(int flags)
                evthread_posix_cond_wait
        };
 
-       if (pthread_mutexattr_init(&attr_default))
-               return -1;
+       pthread_mutex_lock(&once_init_lock);
+       if (once_init == 1) {
+               pthread_mutex_unlock(&once_init_lock);
+               return 0;
+       }
+
+       if (pthread_mutexattr_init(&attr_default)) 
+               goto error;
 
        /* Set ourselves up to get recursive locks. */
        if (pthread_mutexattr_init(&attr_recursive))
-               return -1;
+               goto error;
        if (pthread_mutexattr_settype(&attr_recursive, PTHREAD_MUTEX_RECURSIVE))
-               return -1;
+               goto error;
 
        if (flags & EVTHREAD_PTHREAD_PRIO_INHERIT) {
 #ifdef EVENT__HAVE_PTHREAD_MUTEXATTR_SETPROTOCOL
                /* Set up priority inheritance */
                if (pthread_mutexattr_setprotocol(&attr_default, PTHREAD_PRIO_INHERIT))
-                       return -1;
+                       goto error;
                if (pthread_mutexattr_setprotocol(&attr_recursive, PTHREAD_PRIO_INHERIT))
-                       return -1;
+                       goto error;
 #else
-               return -1;
+               goto error;
 #endif
        }
 
        evthread_set_lock_callbacks(&cbs);
        evthread_set_condition_callbacks(&cond_cbs);
        evthread_set_id_callback(evthread_posix_get_id);
+       once_init = 1;
+       
        return 0;
+error:
+       pthread_mutex_unlock(&once_init_lock);
+       return -1;
 }
 
 int