dispatch.cpp   [plain text]

/*
 * Copyright (c) 2014 Apple Inc. All Rights Reserved.
 * 
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */

//
// dispatch - libdispatch wrapper
//
#include "dispatch.h"
#include <security_utilities/errors.h>

namespace Security {
namespace Dispatch {

ExceptionAwareEnqueuing::ExceptionAwareEnqueuing()
: mExceptionPending(false)
{ }

void ExceptionAwareEnqueuing::enqueueWithDispatcher(void (^dispatcher)(dispatch_block_t), dispatch_block_t block)
{
	if (mExceptionPending)
		return;

	dispatcher(^{
		if (mExceptionPending)
			return;
		try {
			block();
		} catch (...) {
			StLock<Mutex> _(mLock);
			mExceptionPending = true;
			mException = std::current_exception();
		}
	});
}

void ExceptionAwareEnqueuing::throwPendingException()
{
	if (mExceptionPending) {
		mExceptionPending = false;
		std::rethrow_exception(mException);
	}
}



Queue::Queue(const char *label, bool concurrent, dispatch_qos_class_t qos_class)
{
	dispatch_queue_attr_t attr = concurrent ? DISPATCH_QUEUE_CONCURRENT : DISPATCH_QUEUE_SERIAL;
	attr = dispatch_queue_attr_make_with_qos_class(attr, qos_class, 0);
	mQueue = dispatch_queue_create(label, attr);
}

Queue::~Queue()
{
	dispatch_barrier_sync(mQueue, ^{});
	dispatch_release(mQueue);
}

void Queue::enqueue(dispatch_block_t block)
{
	enqueuing.enqueueWithDispatcher(^(dispatch_block_t block){ dispatch_async(mQueue, block); }, block);
}

void Queue::wait()
{
	dispatch_barrier_sync(mQueue, ^{});
	enqueuing.throwPendingException();
}



Group::Group()
{
	mGroup = dispatch_group_create();
}

Group::~Group()
{
	dispatch_group_wait(mGroup, DISPATCH_TIME_FOREVER);
	dispatch_release(mGroup);
}

void Group::enqueue(dispatch_queue_t queue, dispatch_block_t block)
{
	enqueuing.enqueueWithDispatcher(^(dispatch_block_t block){ dispatch_group_async(mGroup, queue, block); }, block);
}

void Group::wait()
{
	dispatch_group_wait(mGroup, DISPATCH_TIME_FOREVER);
	enqueuing.throwPendingException();
}



Semaphore::Semaphore(long count) {
	mSemaphore = dispatch_semaphore_create(count);
}

Semaphore::Semaphore(Semaphore& semaphore)
: mSemaphore(semaphore.mSemaphore)
{
	dispatch_retain(mSemaphore);
}

Semaphore::~Semaphore() {
	dispatch_release(mSemaphore);
}

bool Semaphore::signal() {
	return dispatch_semaphore_signal(mSemaphore) == 0;
}

bool Semaphore::wait(dispatch_time_t timeout) {
	return dispatch_semaphore_wait(mSemaphore, timeout) == 0;
}


// Transfer ownership of held resource.
SemaphoreWait::SemaphoreWait(SemaphoreWait &originalWait)
: mSemaphore(originalWait.mSemaphore), mAcquired(originalWait.mAcquired)
{
	originalWait.mAcquired = false;
}

SemaphoreWait::SemaphoreWait(Semaphore &semaphore, dispatch_time_t timeout)
: mSemaphore(semaphore)
{
	mAcquired = mSemaphore.wait(timeout);
}

SemaphoreWait::~SemaphoreWait()
{
	if (mAcquired)
		mSemaphore.signal();
}


} // end namespace Dispatch
} // end namespace Security