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/*
* Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "MainThread.h"
#include "StdLibExtras.h"
#include "CurrentTime.h"
#include "Deque.h"
#include "Threading.h"
namespace WTF {
struct FunctionWithContext {
MainThreadFunction* function;
void* context;
ThreadCondition* syncFlag;
FunctionWithContext(MainThreadFunction* function = 0, void* context = 0, ThreadCondition* syncFlag = 0)
: function(function)
, context(context)
, syncFlag(syncFlag)
{
}
};
typedef Deque<FunctionWithContext> FunctionQueue;
static bool callbacksPaused; // This global variable is only accessed from main thread.
Mutex& mainThreadFunctionQueueMutex()
{
DEFINE_STATIC_LOCAL(Mutex, staticMutex, ());
return staticMutex;
}
static FunctionQueue& functionQueue()
{
DEFINE_STATIC_LOCAL(FunctionQueue, staticFunctionQueue, ());
return staticFunctionQueue;
}
void initializeMainThread()
{
mainThreadFunctionQueueMutex();
initializeMainThreadPlatform();
}
// 0.1 sec delays in UI is approximate threshold when they become noticeable. Have a limit that's half of that.
static const double maxRunLoopSuspensionTime = 0.05;
void dispatchFunctionsFromMainThread()
{
ASSERT(isMainThread());
if (callbacksPaused)
return;
double startTime = currentTime();
FunctionWithContext invocation;
while (true) {
{
MutexLocker locker(mainThreadFunctionQueueMutex());
if (!functionQueue().size())
break;
invocation = functionQueue().first();
functionQueue().removeFirst();
}
invocation.function(invocation.context);
if (invocation.syncFlag)
invocation.syncFlag->signal();
// If we are running accumulated functions for too long so UI may become unresponsive, we need to
// yield so the user input can be processed. Otherwise user may not be able to even close the window.
// This code has effect only in case the scheduleDispatchFunctionsOnMainThread() is implemented in a way that
// allows input events to be processed before we are back here.
if (currentTime() - startTime > maxRunLoopSuspensionTime) {
scheduleDispatchFunctionsOnMainThread();
break;
}
}
}
void callOnMainThread(MainThreadFunction* function, void* context)
{
ASSERT(function);
bool needToSchedule = false;
{
MutexLocker locker(mainThreadFunctionQueueMutex());
needToSchedule = functionQueue().size() == 0;
functionQueue().append(FunctionWithContext(function, context));
}
if (needToSchedule)
scheduleDispatchFunctionsOnMainThread();
}
void callOnMainThreadAndWait(MainThreadFunction* function, void* context)
{
ASSERT(function);
if (isMainThread()) {
function(context);
return;
}
ThreadCondition syncFlag;
Mutex& functionQueueMutex = mainThreadFunctionQueueMutex();
MutexLocker locker(functionQueueMutex);
functionQueue().append(FunctionWithContext(function, context, &syncFlag));
if (functionQueue().size() == 1)
scheduleDispatchFunctionsOnMainThread();
syncFlag.wait(functionQueueMutex);
}
void setMainThreadCallbacksPaused(bool paused)
{
ASSERT(isMainThread());
if (callbacksPaused == paused)
return;
callbacksPaused = paused;
if (!callbacksPaused)
scheduleDispatchFunctionsOnMainThread();
}
} // namespace WTF
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