158 lines
4.2 KiB
C++
158 lines
4.2 KiB
C++
//+----------------------------------------------------------------------------
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//
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// File: mutex.cpp
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//
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// Module: Common Code
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//
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// Synopsis: Implementation of the class CNamedMutex
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//
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// Copyright (c) 1998-1999 Microsoft Corporation
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//
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// Author: fengsun Created 02/26/98
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//
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//+----------------------------------------------------------------------------
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//+----------------------------------------------------------------------------
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//
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// Function: CNamedMutex::Lock
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//
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// Synopsis:
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//
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// Arguments: LPCTSTR lpName - Name of the mutex
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// BOOL fWait - Whether caller want to wait, if mutex is not available
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// Default is FALSE
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// DWORD dwMilliseconds - Timeout for wait, default is INFINITE
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// BOOL fNoAbandon - Don't acquire an abandoned mutex
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//
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// Returns: BOOL - Whether the mutex is acquired, if TRUE, caller should call
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// Unlock to release the lock. Otherwise, the lock will be
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// released in destructor
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//
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// History: fengsun Created Header 02/26/98
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// nickball Added fNoAbandon 03/32/99
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//
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//+----------------------------------------------------------------------------
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BOOL CNamedMutex::Lock(LPCTSTR lpName, BOOL fWait, DWORD dwMilliseconds, BOOL fNoAbandon)
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{
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MYDBGASSERT(m_hMutex == NULL);
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MYDBGASSERT(lpName);
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m_fOwn = FALSE;
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CMTRACE1(TEXT("CNamedMutex::Lock() - Attempting to acquire mutex - %s"), lpName);
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m_hMutex = CreateMutexU(NULL,TRUE,lpName);
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MYDBGASSERT(m_hMutex);
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if (m_hMutex == NULL)
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{
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return FALSE;
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}
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DWORD dwRet = GetLastError();
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if (dwRet != ERROR_ALREADY_EXISTS)
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{
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//
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// We got the mutex
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//
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m_fOwn = TRUE;
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return TRUE;
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}
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CMTRACE1(TEXT("CNamedMutex::Lock() - Mutex already exists - %s"), lpName);
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//
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// Someone else own the mutex
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//
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if (!fWait) // caller does not want to wait
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{
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CMTRACE1(TEXT("CNamedMutex::Lock() - Not waiting for mutex - %s"), lpName);
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CloseHandle(m_hMutex);
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m_hMutex = NULL;
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return FALSE;
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}
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//
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// Caller want to wait until the mutex is released
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//
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CMTRACE(TEXT("CNamedMutex::Lock() - Entering Mutex wait"));
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dwRet = WaitForSingleObject(m_hMutex, dwMilliseconds);
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switch (dwRet)
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{
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case WAIT_ABANDONED:
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CMTRACE1(TEXT("CNamedMutex::Lock() - Mutex was abandoned by previous owner - %s"), lpName);
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//
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// If the thread that owns a mutex is blown away, the wait will
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// release with a return of WAIT_ABANDON. This typically happens
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// if the thread is dumped from memory, or someone doesn't clean
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// up before terminating. Either way, the caller may not want to
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// acquire an abandoned mutex, so just release it if that is what
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// the caller specified and the wait returned.
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//
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if (fNoAbandon)
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{
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CMTRACE1(TEXT("CNamedMutex::Lock() - Releasing abandoned mutex- %s"), lpName);
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ReleaseMutex(m_hMutex);
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break;
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}
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//
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// Fall through to standard mutex acquisition
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//
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case WAIT_OBJECT_0:
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//
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// We get the mutex
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//
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m_fOwn = TRUE;
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CMTRACE1(TEXT("CNamedMutex::Lock() - Mutex acquired - %s"), lpName);
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return TRUE;
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default:
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CMTRACE1(TEXT("CNamedMutex::Lock() - Mutex wait timed out - %s"), lpName);
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break;
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}
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CloseHandle(m_hMutex);
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m_hMutex = NULL;
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return FALSE;
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}
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//+----------------------------------------------------------------------------
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//
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// Function: CNamedMutex::Unlock
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//
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// Synopsis: Release the mutex
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//
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// Arguments:
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//
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// Returns: NONE
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//
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// History: fengsun Created Header 2/19/98
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//
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//+----------------------------------------------------------------------------
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void CNamedMutex::Unlock()
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{
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if (m_hMutex != NULL)
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{
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if (m_fOwn)
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{
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ReleaseMutex(m_hMutex);
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m_fOwn = FALSE;
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}
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CloseHandle(m_hMutex);
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m_hMutex = NULL;
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}
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}
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