From 1596ea72d66a03d9accb534679172ca6f63f78e1 Mon Sep 17 00:00:00 2001
From: Jeremy Huddleston <jeremyhu@apple.com>
Date: Sat, 23 Apr 2011 11:55:49 -0700
Subject: [PATCH] XQuartz: Use a lighter spinlock instead of a pthread_mutex_t
 in QuartzScreenSaver

Currently, we only end up here through a call to QuartzShowFullscreen, and
this is always on the same thread.  Future changes (such as further
incorporating libdispatch) may allow this to change, but contention will
remain minimal since the call is infrequent and it is short held.

Signed-off-by: Jeremy Huddleston <jeremyhu@apple.com>
Reviewed-by: Daniel A. Steffen <dsteffen@apple.com>
---
 hw/xquartz/quartz.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/hw/xquartz/quartz.c b/hw/xquartz/quartz.c
index 4b72a89d3..0e71d3629 100644
--- a/hw/xquartz/quartz.c
+++ b/hw/xquartz/quartz.c
@@ -62,7 +62,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <IOKit/pwr_mgt/IOPMLib.h>
-#include <pthread.h>
+#include <libkern/OSAtomic.h>
 #include <signal.h>
 
 #include <rootlessCommon.h>
@@ -279,10 +279,10 @@ static void pokeActivityCallback(CFRunLoopTimerRef timer, void *info) {
 static void QuartzScreenSaver(int state) {
     static CFRunLoopTimerRef pokeActivityTimer = NULL;
     static CFRunLoopTimerContext pokeActivityContext = { 0, NULL, NULL, NULL, NULL };
-    static pthread_mutex_t pokeActivityMutex = PTHREAD_MUTEX_INITIALIZER;
+    static OSSpinLock pokeActivitySpinLock = OS_SPINLOCK_INIT;
+
+    OSSpinLockLock(&pokeActivitySpinLock);
 
-    pthread_mutex_lock(&pokeActivityMutex);
-    
     if(state) {
         if(pokeActivityTimer == NULL)
             goto QuartzScreenSaverEnd;
@@ -303,7 +303,7 @@ static void QuartzScreenSaver(int state) {
         CFRunLoopAddTimer(CFRunLoopGetMain(), pokeActivityTimer, kCFRunLoopCommonModes);
     }
 QuartzScreenSaverEnd:
-    pthread_mutex_unlock(&pokeActivityMutex);
+    OSSpinLockUnlock(&pokeActivitySpinLock);
 }
 
 void QuartzShowFullscreen(int state) {