From 0efb67b51e0d9d34c65bbdbd9df567a8a991cc4c Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Sat, 26 Apr 2014 22:11:23 +0200
Subject: DeferredMonitor: fix race condition when using GLib event loop

Turns out the lock-free code using atomics was not thread-safe.  The
given callback could be invoked by GLib before the source_id attribute
was assigned.  This commit changes the DeferredMonitor class to use a
Mutex to block the event loop until source_id is assigned.  This bug
does not exist in the 0.19 branch because it does not use the GLib
main loop anymore.
---
 src/event/DeferredMonitor.hxx | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'src/event/DeferredMonitor.hxx')

diff --git a/src/event/DeferredMonitor.hxx b/src/event/DeferredMonitor.hxx
index 2380fb66f..2ac832a0a 100644
--- a/src/event/DeferredMonitor.hxx
+++ b/src/event/DeferredMonitor.hxx
@@ -27,6 +27,7 @@
 #include "SocketMonitor.hxx"
 #include "WakeFD.hxx"
 #else
+#include "thread/Mutex.hxx"
 #include <glib.h>
 #endif
 
@@ -48,7 +49,9 @@ class DeferredMonitor
 #else
 	EventLoop &loop;
 
-	std::atomic<guint> source_id;
+	Mutex mutex;
+
+	guint source_id;
 #endif
 
 public:
-- 
cgit v1.2.3