[asterisk-commits] mmichelson: branch 1.4 r112468 - /branches/1.4/main/manager.c

[SVN commits to the Asterisk project]

Author: mmichelson
Date: Wed Apr  2 12:36:04 2008
New Revision: 112468

URL: http://svn.digium.com/view/asterisk?view=rev&rev=112468
Log:
Fix a race condition in the manager. It is possible that a new manager event
could be appended during a brief time when the manager is not waiting for input.
If an event comes during this period, we need to set an indicator that there is an
event pending so that the manager doesn't attempt to wait forever for an event that
already happened.

(closes issue #12354)
Reported by: bamby
Patches:
      manager_race_condition.diff uploaded by bamby (license 430)
	  (comments added by me)


Modified:
    branches/1.4/main/manager.c

Modified: branches/1.4/main/manager.c
URL: http://svn.digium.com/view/asterisk/branches/1.4/main/manager.c?view=diff&rev=112468&r1=112467&r2=112468
==============================================================================
--- branches/1.4/main/manager.c (original)
+++ branches/1.4/main/manager.c Wed Apr  2 12:36:04 2008
@@ -175,6 +175,7 @@
 	struct eventqent *eventq;
 	/* Timeout for ast_carefulwrite() */
 	int writetimeout;
+	int pending_event;         /*!< Pending events indicator in case when waiting_thread is NULL */
 	AST_LIST_ENTRY(mansession) list;
 };
 
@@ -2202,6 +2203,11 @@
 	fds[0].events = POLLIN;
 	do {
 		ast_mutex_lock(&s->__lock);
+		if (s->pending_event) {
+			s->pending_event = 0;
+			ast_mutex_unlock(&s->__lock);
+			return 0;
+		}
 		s->waiting_thread = pthread_self();
 		ast_mutex_unlock(&s->__lock);
 
@@ -2463,6 +2469,13 @@
 		ast_mutex_lock(&s->__lock);
 		if (s->waiting_thread != AST_PTHREADT_NULL)
 			pthread_kill(s->waiting_thread, SIGURG);
+		else
+			/* We have an event to process, but the mansession is
+			 * not waiting for it. We still need to indicate that there
+			 * is an event waiting so that get_input processes the pending
+			 * event instead of polling.
+			 */
+			s->pending_event = 1;
 		ast_mutex_unlock(&s->__lock);
 	}
 	AST_LIST_UNLOCK(&sessions);