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117 lines
2.9 KiB
117 lines
2.9 KiB
//
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// The MIT License
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//
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// Copyright (c) 2010 James E Beveridge
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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// This sample code is for my blog entry titled, "Understanding ReadDirectoryChangesW"
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// http://qualapps.blogspot.com/2010/05/understanding-readdirectorychangesw.html
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// See ReadMe.txt for overview information.
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#include <list>
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template <typename C>
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class CThreadSafeQueue : protected std::list<C>
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{
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public:
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CThreadSafeQueue(int nMaxCount)
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{
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m_bOverflow = false;
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m_hSemaphore = ::CreateSemaphore(
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NULL, // no security attributes
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0, // initial count
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nMaxCount, // max count
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NULL); // anonymous
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}
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~CThreadSafeQueue()
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{
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::CloseHandle(m_hSemaphore);
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m_hSemaphore = NULL;
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}
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void push(C& c)
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{
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CComCritSecLock<CComAutoCriticalSection> lock( m_Crit, true );
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push_back( c );
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lock.Unlock();
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if (!::ReleaseSemaphore(m_hSemaphore, 1, NULL))
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{
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// If the semaphore is full, then take back the entry.
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lock.Lock();
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pop_back();
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if (GetLastError() == ERROR_TOO_MANY_POSTS)
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{
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m_bOverflow = true;
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}
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}
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}
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bool pop(C& c)
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{
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CComCritSecLock<CComAutoCriticalSection> lock( m_Crit, true );
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// If the user calls pop() more than once after the
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// semaphore is signaled, then the semaphore count will
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// get out of sync. We fix that when the queue empties.
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if (empty())
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{
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while (::WaitForSingleObject(m_hSemaphore, 0) != WAIT_TIMEOUT)
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1;
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return false;
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}
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c = front();
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pop_front();
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return true;
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}
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// If overflow, use this to clear the queue.
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void clear()
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{
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CComCritSecLock<CComAutoCriticalSection> lock( m_Crit, true );
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for (DWORD i=0; i<size(); i++)
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WaitForSingleObject(m_hSemaphore, 0);
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__super::clear();
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m_bOverflow = false;
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}
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bool overflow()
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{
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return m_bOverflow;
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}
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HANDLE GetWaitHandle() { return m_hSemaphore; }
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protected:
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HANDLE m_hSemaphore;
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CComAutoCriticalSection m_Crit;
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bool m_bOverflow;
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};
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