gls_mutex.h

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/*! \file
  \brief  A cross platform mutex implementation.

  \par Copyright Information

  Copyright (c) 2017 by The DiSTI Corporation.<br>
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  NO WARRANTY. THE SOFTWARE IS PROVIDED "AS-IS," WITHOUT WARRANTY OF ANY KIND,
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*/

#ifndef INCLUDED_DISTI_MUTEX_H
#define INCLUDED_DISTI_MUTEX_H

#include "disti_include.h"

namespace disti
{
/**
    Provide a cross platform Mutex class to provide data locking capability in 
    a multithreaded environment. Uses the pimpl idiom to hide details.
*/
class Mutex
{
public:
    /// Constructor
    DISTI_EXPORT Mutex();

    /// Destructor
    virtual DISTI_EXPORT ~Mutex();

    /// Blocks to acquire the mutex
    DISTI_EXPORT void Lock();

    /// Attemps to acquire the mutex without blocking
    /// \return whether the lock succeeded
    DISTI_EXPORT bool TryLock();

    /// Releases the mutex, allowing another process to lock it
    DISTI_EXPORT void Unlock();

    /// A lock class to automagically un/lock a mutex within its scope
    class ScopedLock
    {
    public:
        /// Lock the given mutex (blocks on failure to acquire)
        ScopedLock( Mutex& mut )
            : _mut( mut )
        {
            _mut.Lock();
        }

        /// Releases the mutex automatically
        ~ScopedLock()
        {
            _mut.Unlock();
        }

    private:
        Mutex& _mut;
    };

    /// A lock to automagically try to lock and, if applicable, unlock a mutex within its scope.
    class ScopedTryLock
    {
    public:
        /// Tries to lock the given mutex
        ScopedTryLock( Mutex& mut )
            : _mut( mut )
            , _locked( _mut.TryLock() )
        {}

        /// Returns whether the lock succeeded
        bool IsLocked() const { return _locked; }

        /// Releases the mutex automatically, if needed
        ~ScopedTryLock()
        {
            if( _locked )
            {
                _mut.Unlock();
            }
        }

    private:
        Mutex& _mut;
        bool   _locked;
    };

private:
    // The pimpl idiom
    class Impl;
    Impl* const _impl;

    // Disable copying
    Mutex( const Mutex& );
    void operator=( const Mutex& );
};

} // namespace disti

#endif