mirror of
https://github.com/kyleneideck/BackgroundMusic
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235 lines
9.7 KiB
C++
235 lines
9.7 KiB
C++
/*
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File: CADispatchQueue.h
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Abstract: Part of CoreAudio Utility Classes
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Version: 1.0.1
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Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple
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Inc. ("Apple") in consideration of your agreement to the following
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terms, and your use, installation, modification or redistribution of
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this Apple software constitutes acceptance of these terms. If you do
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not agree with these terms, please do not use, install, modify or
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redistribute this Apple software.
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In consideration of your agreement to abide by the following terms, and
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subject to these terms, Apple grants you a personal, non-exclusive
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license, under Apple's copyrights in this original Apple software (the
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"Apple Software"), to use, reproduce, modify and redistribute the Apple
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Software, with or without modifications, in source and/or binary forms;
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provided that if you redistribute the Apple Software in its entirety and
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without modifications, you must retain this notice and the following
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text and disclaimers in all such redistributions of the Apple Software.
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Neither the name, trademarks, service marks or logos of Apple Inc. may
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be used to endorse or promote products derived from the Apple Software
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without specific prior written permission from Apple. Except as
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expressly stated in this notice, no other rights or licenses, express or
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implied, are granted by Apple herein, including but not limited to any
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patent rights that may be infringed by your derivative works or by other
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works in which the Apple Software may be incorporated.
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The Apple Software is provided by Apple on an "AS IS" basis. APPLE
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MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
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THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS
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FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND
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OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.
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IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL
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OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,
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MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED
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AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),
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STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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Copyright (C) 2013 Apple Inc. All Rights Reserved.
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*/
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/*==================================================================================================
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CADispatchQueue.h
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==================================================================================================*/
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#if !defined(__CADispatchQueue_h__)
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#define __CADispatchQueue_h__
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//==================================================================================================
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// Includes
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//==================================================================================================
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// System Includes
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#include <CoreFoundation/CFString.h>
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#include <dispatch/dispatch.h>
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// Standard Library Includes
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#include <functional>
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#include <vector>
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/*==================================================================================================
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CADispatchQueue
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This class provides a wrapper for a libdispatch dispatch queue and several kinds of event
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sources such as MIG servers, port death notifications and other mach port related support. Being
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a libdispatch client, the unit of work is represented as either a function pointer and context
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pointer pair or as a Block.
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One thing to keep in mind when using a Block-based construct is that you get a copy of the
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pointer but you do not get a copy of the memory that the pointer is pointing at. The net effect
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is that if you have a task that frees the memory that is referenced by a subsequent task,
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this second task would crash when dereferencing the pointer. This means that every task
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needs to include some code to validate any pointers it is using before dereferencing them.
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A common example of this problem comes up with C++ objects. Suppose you have an instance method
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that creates a Block that calls other instance methods or accesses the object's fields. Suppose
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further that the Block is submitted to a dispatch queue for execution. If the object gets
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deallocated before the Block can run, the Block will crash. Thus, the Block needs to validate
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that the "this" pointer is still valid when it executes.
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Another place where this comes up often is when attempting to implment a function by dispatching
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the work asynchronously. Any arguments to the function that point to the stack will be invalid.
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This is particularly troublesome inside of a MIG function.
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Still another common issue with using Blocks and dispatch functions with C++ is that it is vital
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that no exceptions ever leave a Block or a dispatch function. If an exception was thrown out of
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a block, the result would be undefined and probably would result in the program calling
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the terminate() function in the standard C++ library (whose default implementation is to call
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abort(3)). Given that, all Blocks and dispatch functions that might end up throwing an exception
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need to catch those exceptions.
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==================================================================================================*/
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class CADispatchQueue
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{
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#pragma mark Construction/Destruction
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public:
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CADispatchQueue(const char* inName);
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CADispatchQueue(CFStringRef inName);
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CADispatchQueue(CFStringRef inPattern, CFStringRef inName);
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virtual ~CADispatchQueue();
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private:
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CADispatchQueue(const CADispatchQueue&);
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CADispatchQueue& operator=(const CADispatchQueue&);
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#pragma mark Execution Operations
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public:
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void Dispatch(bool inDoSync, dispatch_block_t inTask) const;
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void Dispatch(UInt64 inNanoseconds, dispatch_block_t inTask) const;
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void Dispatch(bool inDoSync, void* inTaskContext, dispatch_function_t inTask) const;
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void Dispatch(UInt64 inNanoseconds, void* inTaskContext, dispatch_function_t inTask) const;
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static void Dispatch_Global(dispatch_queue_priority_t inQueuePriority, bool inDoSync, dispatch_block_t inTask);
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static void Dispatch_Global(dispatch_queue_priority_t inQueuePriority, UInt64 inNanoseconds, dispatch_block_t inTask);
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static void Dispatch_Global(dispatch_queue_priority_t inQueuePriority, bool inDoSync, void* inTaskContext, dispatch_function_t inTask);
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static void Dispatch_Global(dispatch_queue_priority_t inQueuePriority, UInt64 inNanoseconds, void* inTaskContext, dispatch_function_t inTask);
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static void Dispatch_Main(bool inDoSync, dispatch_block_t inTask);
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static void Dispatch_Main(UInt64 inNanoseconds, dispatch_block_t inTask);
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static void Dispatch_Main(bool inDoSync, void* inTaskContext, dispatch_function_t inTask);
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static void Dispatch_Main(UInt64 inNanoseconds, void* inTaskContext, dispatch_function_t inTask);
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#pragma mark Event Sources
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public:
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void InstallMachPortDeathNotification(mach_port_t inMachPort, dispatch_block_t inNotificationTask);
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void RemoveMachPortDeathNotification(mach_port_t inMachPort);
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void InstallMachPortReceiver(mach_port_t inMachPort, dispatch_block_t inMessageTask);
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void RemoveMachPortReceiver(mach_port_t inMachPort, dispatch_block_t inCompletionTask);
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void RemoveMachPortReceiver(mach_port_t inMachPort, bool inDestroySendRight, bool inDestroyReceiveRight);
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#pragma mark Implementation
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public:
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dispatch_queue_t GetDispatchQueue() const;
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static CADispatchQueue& GetGlobalSerialQueue();
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protected:
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static void InitializeGlobalSerialQueue(void*);
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struct EventSource
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{
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dispatch_source_t mDispatchSource;
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mach_port_t mMachPort;
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EventSource();
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EventSource(dispatch_source_t inDispatchSource, mach_port_t inMachPort);
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EventSource(const EventSource& inEventSource);
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EventSource& operator=(const EventSource& inEventSource);
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~EventSource();
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void Retain();
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void Release();
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};
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typedef std::vector<EventSource> EventSourceList;
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dispatch_queue_t mDispatchQueue;
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EventSourceList mPortDeathList;
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EventSourceList mMachPortReceiverList;
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static CADispatchQueue* sGlobalSerialQueue;
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static dispatch_once_t sGlobalSerialQueueInitialized;
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};
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//==================================================================================================
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#pragma mark CADispatchQueue Inline Method Implementations
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//==================================================================================================
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inline dispatch_queue_t CADispatchQueue::GetDispatchQueue() const
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{
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return mDispatchQueue;
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}
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inline CADispatchQueue::EventSource::EventSource()
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:
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mDispatchSource(NULL),
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mMachPort(MACH_PORT_NULL)
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{
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}
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inline CADispatchQueue::EventSource::EventSource(dispatch_source_t inDispatchSource, mach_port_t inMachPort)
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:
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mDispatchSource(inDispatchSource),
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mMachPort(inMachPort)
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{
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}
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inline CADispatchQueue::EventSource::EventSource(const EventSource& inEventSource)
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:
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mDispatchSource(inEventSource.mDispatchSource),
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mMachPort(inEventSource.mMachPort)
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{
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Retain();
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}
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inline CADispatchQueue::EventSource& CADispatchQueue::EventSource::operator=(const EventSource& inEventSource)
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{
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Release();
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mDispatchSource = inEventSource.mDispatchSource;
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mMachPort = inEventSource.mMachPort;
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Retain();
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return *this;
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}
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inline CADispatchQueue::EventSource::~EventSource()
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{
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Release();
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}
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inline void CADispatchQueue::EventSource::Retain()
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{
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if(mDispatchSource != NULL)
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{
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dispatch_retain(mDispatchSource);
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}
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}
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inline void CADispatchQueue::EventSource::Release()
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{
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if(mDispatchSource != NULL)
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{
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dispatch_release(mDispatchSource);
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mDispatchSource = NULL;
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}
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}
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#endif // __CADispatchQueue_h__
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