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NamedMutex.h

//
// NamedMutex.h
//
// $Id: //poco/1.3/Foundation/include/Poco/NamedMutex.h#1 $
//
// Library: Foundation
// Package: Processes
// Module:  NamedMutex
//
// Definition of the NamedMutex class.
//
// Copyright (c) 2004-2006, 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_NamedMutex_INCLUDED
#define Foundation_NamedMutex_INCLUDED


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


#if defined(POCO_OS_FAMILY_WINDOWS) && defined(POCO_WIN32_UTF8)
#include "Poco/NamedMutex_WIN32U.h"
#elif defined(POCO_OS_FAMILY_WINDOWS)
#include "Poco/NamedMutex_WIN32.h"
#elif defined(POCO_OS_FAMILY_UNIX)
#include "Poco/NamedMutex_UNIX.h"
#else
#include "Poco/NamedMutex_VMS.h"
#endif


namespace Poco {


00061 class Foundation_API NamedMutex: private NamedMutexImpl
      /// A NamedMutex (mutual exclusion) is a global synchronization 
      /// mechanism used to control access to a shared resource
      /// in a concurrent (multi process) scenario.
      /// Using the ScopedLock class is the preferred way to automatically
      /// lock and unlock a mutex.
      ///
      /// Unlike a Mutex or a FastMutex, which itself is the unit of synchronization,
      /// a NamedMutex refers to a named operating system resource being the
      /// unit of synchronization.
      /// In other words, there can be multiple instances of NamedMutex referring
      /// to the same actual synchronization object.
      ///
      ///
      /// There should not be more than one instance of NamedMutex for
      /// a given name in a process. Otherwise, the instances may
      /// interfere with each other.
{
public:
      typedef Poco::ScopedLock<NamedMutex> ScopedLock;
      
      NamedMutex(const std::string& name);
            /// creates the Mutex.
            
      ~NamedMutex();
            /// destroys the Mutex.

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

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

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


//
// inlines
//
00111 inline void NamedMutex::lock()
{
      lockImpl();
}


00117 inline bool NamedMutex::tryLock()
{
      return tryLockImpl();
}


00123 inline void NamedMutex::unlock()
{
      unlockImpl();
}


} // namespace Poco


#endif // Foundation_NamedMutex_INCLUDED

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