ovs-thread: Add support for convenient once-only initializers.

pthread_once() is portable but it does not allow passing any parameters to
the initialization function, which is often inconvenient, because it means
that the function can only access data declared at file scope.  This commit
introduces an alternative with a more convenient interface.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c
index 23224323..e1e72891 100644
--- a/lib/ovs-thread.c
+++ b/lib/ovs-thread.c
@@ -88,4 +88,22 @@ xpthread_create(pthread_t *threadp, pthread_attr_t *attr,
         ovs_abort(error, "pthread_create failed");
     }
 }
+
+bool
+ovsthread_once_start__(struct ovsthread_once *once)
+{
+    xpthread_mutex_lock(&once->mutex);
+    if (!ovsthread_once_is_done__(once)) {
+        return false;
+    }
+    xpthread_mutex_unlock(&once->mutex);
+    return true;
+}
+
+void OVS_RELEASES(once)
+ovsthread_once_done(struct ovsthread_once *once)
+{
+    atomic_store(&once->done, true);
+    xpthread_mutex_unlock(&once->mutex);
+}
 #endif