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https://github.com/holub/mame
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79 lines
2.3 KiB
C++
79 lines
2.3 KiB
C++
// StreamBinder.h
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#ifndef __STREAM_BINDER_H
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#define __STREAM_BINDER_H
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#include "../../Windows/Synchronization.h"
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#include "../IStream.h"
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/*
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We can use one from two code versions here: with Event or with Semaphore to unlock Writer thread
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The difference for cases where Reading must be closed before Writing closing
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1) Event Version: _canWrite_Event
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We call _canWrite_Event.Set() without waiting _canRead_Event in CloseRead() function.
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The writer thread can get (_readingWasClosed) status in one from two iterations.
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It's ambiguity of processing flow. But probably it's SAFE to use, if Event functions provide memory barriers.
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reader thread:
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_canWrite_Event.Set();
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_readingWasClosed = true;
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_canWrite_Event.Set();
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writer thread:
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_canWrite_Event.Wait()
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if (_readingWasClosed)
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2) Semaphore Version: _canWrite_Semaphore
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writer thread always will detect closing of reading in latest iteration after all data processing iterations
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*/
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class CStreamBinder
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{
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NWindows::NSynchronization::CAutoResetEvent _canRead_Event;
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// NWindows::NSynchronization::CAutoResetEvent _canWrite_Event;
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NWindows::NSynchronization::CSemaphore _canWrite_Semaphore;
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// bool _readingWasClosed; // set it in reader thread and check it in write thread
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bool _readingWasClosed2; // use it in writer thread
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// bool WritingWasCut;
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bool _waitWrite; // use it in reader thread
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UInt32 _bufSize;
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const void *_buf;
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public:
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UInt64 ProcessedSize; // the size that was read by reader thread
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void CreateStreams2(CMyComPtr<ISequentialInStream> &inStream, CMyComPtr<ISequentialOutStream> &outStream);
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HRESULT Create_ReInit();
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HRESULT Read(void *data, UInt32 size, UInt32 *processedSize);
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HRESULT Write(const void *data, UInt32 size, UInt32 *processedSize);
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void CloseRead_CallOnce()
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{
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// call it only once: for example, in destructor
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/*
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_readingWasClosed = true;
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_canWrite_Event.Set();
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*/
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/*
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We must relase Semaphore only once !!!
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we must release at least 2 items of Semaphore:
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one item to unlock partial Write(), if Read() have read some items
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then additional item to stop writing (_bufSize will be 0)
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*/
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_canWrite_Semaphore.Release(2);
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}
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void CloseWrite()
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{
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_buf = NULL;
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_bufSize = 0;
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_canRead_Event.Set();
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}
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};
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#endif
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