Fixing bug 139802 on the branch. Avoid spending lots of time in WaitNextEvent when there are NSPR threads running. r=wtc, sdagley. a=chofmann

2 files changed, 26 insertions, 7 deletions

diff --git a/pr/src/md/mac/macthr.c b/pr/src/md/mac/macthr.c
index e84e38a2..6a1f18d4 100644
--- a/pr/src/md/mac/macthr.c
+++ b/pr/src/md/mac/macthr.c
@@ -49,6 +49,8 @@
 TimerUPP	gTimerCallbackUPP	= NULL;
 PRThread *	gPrimaryThread		= NULL;
 
+ProcessSerialNumber		gApplicationProcess;
+
 PR_IMPLEMENT(PRThread *) PR_GetPrimaryThread()
 {
 	return gPrimaryThread;
@@ -159,7 +161,21 @@ extern void _MD_ClearStack(PRThreadStack *ts)
 #pragma mark -
 #pragma mark TIME MANAGER-BASED CLOCK
 
-TMTask		gTimeManagerTaskElem;
+// On Mac OS X, it's possible for the application to spend lots of time
+// in WaitNextEvent, yielding to other applications. Since NSPR threads are
+// cooperative here, this means that NSPR threads will also get very little
+// time to run. To kick ourselves out of a WaitNextEvent call when we have
+// determined that it's time to schedule another thread, the Timer Task
+// (which fires every 8ms, even when other apps have the CPU) calls WakeUpProcess.
+// We only want to do this on Mac OS X; the gTimeManagerTaskDoesWUP variable
+// indicates when we're running on that OS.
+//
+// Note that the TimerCallback makes use of gApplicationProcess. We need to
+// have set this up before the first possible run of the timer task; we do
+// so in _MD_EarlyInit().
+static Boolean  gTimeManagerTaskDoesWUP;
+
+static TMTask   gTimeManagerTaskElem;
 
 extern void _MD_IOInterrupt(void);
 _PRInterruptTable _pr_interruptTable[] = {
@@ -184,8 +200,11 @@ pascal void TimerCallback(TMTaskPtr tmTaskPtr)
     //	And tell nspr that a clock interrupt occured.
     _PR_ClockInterrupt();
 	
-    if ((_PR_RUNQREADYMASK(cpu)) >> ((_PR_MD_CURRENT_THREAD()->priority)))
+    if ((_PR_RUNQREADYMASK(cpu)) >> ((_PR_MD_CURRENT_THREAD()->priority))) {
+        if (gTimeManagerTaskDoesWUP)
+            WakeUpProcess(&gApplicationProcess);
         _PR_SET_RESCHED_FLAG();
+	}
 	
     _PR_FAST_INTSON(is);
 
@@ -198,6 +217,8 @@ void _MD_StartInterrupts(void)
 {
 	gPrimaryThread = _PR_MD_CURRENT_THREAD();
 
+	gTimeManagerTaskDoesWUP = RunningOnOSX();
+
 	if ( !gTimerCallbackUPP )
 		gTimerCallbackUPP = NewTimerUPP(TimerCallback);
 
@@ -607,7 +628,6 @@ void LeaveCritialRegion()
 PRBool					gUseIdleSemaphore = PR_FALSE;
 MPSemaphoreID			gIdleSemaphore = NULL;
 #endif
-ProcessSerialNumber		gApplicationProcess;
 
 void InitIdleSemaphore()
 {
@@ -619,11 +639,7 @@ void InitIdleSemaphore()
 		OSStatus  err = MPCreateSemaphore(1 /* max value */, 0 /* initial value */, &gIdleSemaphore);
 		PR_ASSERT(err == noErr);
 	}
-	else
 #endif
-	{
-		GetCurrentProcess(&gApplicationProcess);
-	}
 }
 
 void TermIdleSemaphore()
diff --git a/pr/src/md/mac/mdmac.c b/pr/src/md/mac/mdmac.c
index cfa33b4f..6d65e578 100644
--- a/pr/src/md/mac/mdmac.c
+++ b/pr/src/md/mac/mdmac.c
@@ -70,6 +70,7 @@
 unsigned char GarbageCollectorCacheFlusher(PRUint32 size);
 
 extern PRThread *gPrimaryThread;
+extern ProcessSerialNumber gApplicationProcess;     // in macthr.c
 
 
 //##############################################################################
@@ -288,6 +289,8 @@ void _MD_EarlyInit()
 {
 	Handle				environmentVariables;
 
+	GetCurrentProcess(&gApplicationProcess);
+
 	INIT_CRITICAL_REGION();
 	InitIdleSemaphore();