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Mutex.h
//
// Mutex.h
//
// $Id: //poco/1.3/Foundation/include/Poco/Mutex.h#2 $
//
// Library: Foundation
// Package: Threading
// Module:  Mutex
//
// Definition of the Mutex and FastMutex classes.
//
// Copyright (c) 2004-2008, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_Mutex_INCLUDED
#define Foundation_Mutex_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/Exception.h"
#include "Poco/ScopedLock.h"


#if defined(POCO_OS_FAMILY_WINDOWS)
#include "Poco/Mutex_WIN32.h"
#else
#include "Poco/Mutex_POSIX.h"
#endif


namespace Poco {


00058 class Foundation_API Mutex: private MutexImpl
      /// A Mutex (mutual exclusion) is a synchronization 
      /// mechanism used to control access to a shared resource
      /// in a concurrent (multithreaded) scenario.
      /// Mutexes are recursive, that is, the same mutex can be 
      /// locked multiple times by the same thread (but, of course,
      /// not by other threads).
      /// Using the ScopedLock class is the preferred way to automatically
      /// lock and unlock a mutex.
{
public:
      typedef Poco::ScopedLock<Mutex> ScopedLock;
      
      Mutex();
            /// creates the Mutex.
            
      ~Mutex();
            /// destroys the Mutex.

      void lock();
            /// Locks the mutex. Blocks if the mutex
            /// is held by another thread.
            
      void lock(long milliseconds);
            /// Locks the mutex. Blocks up to the given number of milliseconds
            /// if the mutex is held by another thread. Throws a TimeoutException
            /// if the mutex can not be locked within the given timeout.
            ///
            /// Performance Note: On most platforms (including Windows), this member function is 
            /// implemented using a loop calling (the equivalent of) tryLock() and Thread::sleep().
            /// On POSIX platforms that support pthread_mutex_timedlock(), this is used.

      bool tryLock();
            /// Tries to lock the mutex. Returns false immediately
            /// if the mutex is already held by another thread.
            /// Returns true if the mutex was successfully locked.

      bool tryLock(long milliseconds);
            /// Locks the mutex. Blocks up to the given number of milliseconds
            /// if the mutex is held by another thread.
            /// Returns true if the mutex was successfully locked.
            ///
            /// Performance Note: On most platforms (including Windows), this member function is 
            /// implemented using a loop calling (the equivalent of) tryLock() and Thread::sleep().
            /// On POSIX platforms that support pthread_mutex_timedlock(), this is used.

      void unlock();
            /// Unlocks the mutex so that it can be acquired by
            /// other threads.
      
private:
      Mutex(const Mutex&);
      Mutex& operator = (const Mutex&);
};


00114 class Foundation_API FastMutex: private FastMutexImpl
      /// A FastMutex (mutual exclusion) is similar to a Mutex.
      /// Unlike a Mutex, however, a FastMutex is not recursive,
      /// which means that a deadlock will occur if the same
      /// thread tries to lock a mutex it has already locked again.
      /// Locking a FastMutex is faster than locking a recursive Mutex.
      /// Using the ScopedLock class is the preferred way to automatically
      /// lock and unlock a mutex.
{
public:
      typedef Poco::ScopedLock<FastMutex> ScopedLock;

      FastMutex();
            /// creates the Mutex.
            
      ~FastMutex();
            /// destroys the Mutex.

      void lock();
            /// Locks the mutex. Blocks if the mutex
            /// is held by another thread.

      void lock(long milliseconds);
            /// Locks the mutex. Blocks up to the given number of milliseconds
            /// if the mutex is held by another thread. Throws a TimeoutException
            /// if the mutex can not be locked within the given timeout.
            ///
            /// Performance Note: On most platforms (including Windows), this member function is 
            /// implemented using a loop calling (the equivalent of) tryLock() and Thread::sleep().
            /// On POSIX platforms that support pthread_mutex_timedlock(), this is used.

      bool tryLock();
            /// Tries to lock the mutex. Returns false immediately
            /// if the mutex is already held by another thread.
            /// Returns true if the mutex was successfully locked.

      bool tryLock(long milliseconds);
            /// Locks the mutex. Blocks up to the given number of milliseconds
            /// if the mutex is held by another thread.
            /// Returns true if the mutex was successfully locked.
            ///
            /// Performance Note: On most platforms (including Windows), this member function is 
            /// implemented using a loop calling (the equivalent of) tryLock() and Thread::sleep().
            /// On POSIX platforms that support pthread_mutex_timedlock(), this is used.

      void unlock();
            /// Unlocks the mutex so that it can be acquired by
            /// other threads.
      
private:
      FastMutex(const FastMutex&);
      FastMutex& operator = (const FastMutex&);
};


//
// inlines
//
00172 inline void Mutex::lock()
{
      lockImpl();
}


00178 inline void Mutex::lock(long milliseconds)
{
      if (!tryLockImpl(milliseconds))
            throw TimeoutException();
}


00185 inline bool Mutex::tryLock()
{
      return tryLockImpl();
}


00191 inline bool Mutex::tryLock(long milliseconds)
{
      return tryLockImpl(milliseconds);
}


00197 inline void Mutex::unlock()
{
      unlockImpl();
}


00203 inline void FastMutex::lock()
{
      lockImpl();
}


00209 inline void FastMutex::lock(long milliseconds)
{
      if (!tryLockImpl(milliseconds))
            throw TimeoutException();
}


00216 inline bool FastMutex::tryLock()
{
      return tryLockImpl();
}


00222 inline bool FastMutex::tryLock(long milliseconds)
{
      return tryLockImpl(milliseconds);
}


00228 inline void FastMutex::unlock()
{
      unlockImpl();
}


} // namespace Poco


#endif // Foundation_Mutex_INCLUDED

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