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csutil/threading/win32_mutex.h

00001 /*
00002   Copyright (C) 2006 by Marten Svanfeldt
00003 
00004   This library is free software; you can redistribute it and/or
00005   modify it under the terms of the GNU Lesser General Public
00006   License as published by the Free Software Foundation; either
00007   version 2 of the License, or (at your option) any later version.
00008 
00009   This library is distributed in the hope that it will be useful,
00010   but WITHOUT ANY WARRANTY; without even the implied warranty of
00011   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012   Library General Public License for more details.
00013 
00014   You should have received a copy of the GNU Library General Public
00015   License along with this library; if not, write to the Free
00016   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00017 */
00018 
00019 #ifndef __CS_CSUTIL_THREADING_WIN32_MUTEX_H__
00020 #define __CS_CSUTIL_THREADING_WIN32_MUTEX_H__
00021 
00022 #include "csutil/threading/atomicops.h"
00023 #include "csutil/threading/win32_apifuncs.h"
00024 
00025 #if !defined(CS_PLATFORM_WIN32)
00026 #error "This file is only for Windows and requires you to include csysdefs.h before"
00027 #else
00028 
00029 namespace CS
00030 {
00031 namespace Threading
00032 {
00033 namespace Implementation
00034 {
00035 
00039   class MutexBase
00040   {
00041   public:
00042     void Initialize ()
00043     {
00044       activeFlag = 0;
00045       semaphore = 0;
00046     }
00047 
00048     void Destroy ()
00049     {
00050       void* oldSemaphore = AtomicOperations::Set (&semaphore, (void*)0);
00051       if (oldSemaphore)
00052       {
00053         Implementation::CloseHandle (semaphore);
00054       }
00055     }
00056     
00057     bool IsLocked ()
00058     {
00059       return AtomicOperations::Read (&activeFlag) > 0;
00060     }
00061 
00062     bool Lock ()
00063     {
00064       if (AtomicOperations::Increment (&activeFlag) != 1)
00065       {
00066         Implementation::WaitForSingleObject (GetSemaphore (), INFINITE);
00067       }
00068       return IsLocked ();
00069     }
00070 
00071     bool TryLock ()
00072     {
00073       return !AtomicOperations::CompareAndSet (&activeFlag, 1, 0);
00074     }
00075 
00076     void Unlock ()
00077     {
00078       if (AtomicOperations::Decrement (&activeFlag) > 0)
00079       {
00080         Implementation::ReleaseSemaphore (GetSemaphore (), 1, 0);
00081       }
00082     }
00083 
00084   private:
00085     void* GetSemaphore ()
00086     {
00087       void* currentSem = AtomicOperations::Read (&semaphore);
00088       if (!currentSem)
00089       {
00090         //Create a new semaphore and try to set it
00091         void* const newSem = Implementation::CreateSemaphoreA (0,0,1,0);
00092         void* const oldSem = AtomicOperations::CompareAndSet (&semaphore, 
00093           newSem, 0);
00094 
00095         //We already have one, use it
00096         if (oldSem != 0)
00097         {
00098           Implementation::CloseHandle (newSem);
00099           return oldSem;
00100         }
00101         else
00102         {
00103           //We didn't have any before, so use our new semaphore
00104           return newSem;
00105         }
00106       }
00107       return currentSem;
00108     }
00109 
00110     int32 activeFlag; //Lock flag for mutex
00111     void* semaphore; //Semaphore for being able to wait for
00112   };
00113 
00114 
00118   class RecursiveMutexBase
00119   {
00120   public:
00121     void Initialize ()
00122     {
00123       recursionCount = 0;
00124       lockingThreadID = 0;
00125       mutex.Initialize ();
00126     }
00127 
00128     void Destroy ()
00129     {
00130       mutex.Destroy ();
00131     }
00132 
00133     bool IsLocked ()
00134     {
00135       return mutex.IsLocked ();
00136     }
00137 
00138     bool Lock ()
00139     {
00140       int32 currentThreadID = (int32)Implementation::GetCurrentThreadId ();
00141       if (!TryRecursiveLock (currentThreadID))
00142       {
00143         mutex.Lock ();
00144         AtomicOperations::Set (&lockingThreadID, currentThreadID);
00145         recursionCount = 1;
00146       }
00147       return IsLocked ();
00148     }
00149 
00150     bool TryLock ()
00151     {
00152       int32 currentThreadID = (int32)Implementation::GetCurrentThreadId ();
00153       return TryRecursiveLock (currentThreadID) || 
00154              TryNormalLock (currentThreadID);
00155     }
00156 
00157     void Unlock ()
00158     {
00159       if(!--recursionCount)
00160       {
00161         AtomicOperations::Set (&lockingThreadID, 0);
00162         mutex.Unlock ();
00163       }
00164     }
00165 
00166   private:
00167     bool TryRecursiveLock (int32 currentThreadID)
00168     {
00169       if (AtomicOperations::Read (&lockingThreadID) == currentThreadID)
00170       {
00171         ++recursionCount;
00172         return true;
00173       }
00174       return false;
00175     }
00176 
00177     bool TryNormalLock (int32 currentThreadID)
00178     {
00179       if (mutex.TryLock ())
00180       {
00181         AtomicOperations::Set (&lockingThreadID, currentThreadID);
00182         recursionCount = 1;
00183         return true;
00184       }
00185       return false;
00186     }
00187 
00188     MutexBase mutex; //Non-recursive base-mutex
00189     int32 recursionCount;
00190     int32 lockingThreadID;
00191   }; 
00192 
00193 } // namespace Implementation
00194 } // namespace Threading
00195 } // namespace CS
00196 
00197 #endif // !defined(CS_PLATFORM_WIN32)
00198 
00199 #endif // __CS_CSUTIL_THREADING_WIN32_MUTEX_H__

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