source: XMLIO_V2/external/src/POCO/Foundation.save/Poco/AtomicCounter.h @ 80

//
// AtomicCounter.h
//
// $Id: //poco/1.3/Foundation/include/Poco/AtomicCounter.h#6 $
//
// Library: Foundation
// Package: Core
// Module:  AtomicCounter
//
// Definition of the AtomicCounter class.
//
// Copyright (c) 2009, 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_AtomicCounter_INCLUDED
#define Foundation_AtomicCounter_INCLUDED


#include "Poco/Foundation.h"
#if POCO_OS == POCO_OS_WINDOWS_NT
#include "Poco/UnWindows.h"
#elif POCO_OS == POCO_OS_MAC_OS_X
#include <libkern/OSAtomic.h>
#else
#include "Poco/Mutex.h"
#endif // POCO_OS


namespace Poco {


class Foundation_API AtomicCounter
        /// This class implements a simple counter, which
        /// provides atomic operations that are safe to
        /// use in a multithreaded environment.
        ///
        /// Typical usage of AtomicCounter is for implementing
        /// reference counting and similar things.
        ///
        /// On some platforms, the implementation of AtomicCounter
        /// is based on atomic primitives specific to the platform
        /// (such as InterlockedIncrement, etc. on Windows), and
        /// thus very efficient. On platforms that do not support
        /// atomic primitives, operations are guarded by a FastMutex.
        ///
        /// The following platforms currently have atomic
        /// primitives:
        ///   - Windows
        ///   - Mac OS X
{
public:
        typedef int ValueType; /// The underlying integer type.
        
        AtomicCounter();
                /// Creates a new AtomicCounter and initializes it to zero.
                
        explicit AtomicCounter(ValueType initialValue);
                /// Creates a new AtomicCounter and initializes it with
                /// the given value.
        
        AtomicCounter(const AtomicCounter& counter);
                /// Creates the counter by copying another one.
        
        ~AtomicCounter();
                /// Destroys the AtomicCounter.

        AtomicCounter& operator = (const AtomicCounter& counter);
                /// Assigns the value of another AtomicCounter.
                
        AtomicCounter& operator = (ValueType value);
                /// Assigns a value to the counter.

        operator ValueType () const;
                /// Returns the value of the counter.
                
        ValueType value() const;
                /// Returns the value of the counter.
                
        ValueType operator ++ (); // prefix
                /// Increments the counter and returns the result.
                
        ValueType operator ++ (int); // postfix
                /// Increments the counter and returns the previous value.
                
        ValueType operator -- (); // prefix
                /// Decrements the counter and returns the result.
                
        ValueType operator -- (int); // postfix
                /// Decrements the counter and returns the previous value.
                
        bool operator ! () const;
                /// Returns true if the counter is zero, false otherwise.

private:
#if POCO_OS == POCO_OS_WINDOWS_NT
        typedef volatile LONG ImplType;
#elif POCO_OS == POCO_OS_MAC_OS_X
        typedef int32_t ImplType;
#else // generic implementation based on FastMutex
        struct ImplType
        {
                mutable FastMutex mutex;
                volatile int      value;
        };
#endif // POCO_OS

        ImplType _counter;
};


//
// inlines
//


#if POCO_OS == POCO_OS_WINDOWS_NT
//
// Windows
//
inline AtomicCounter::operator AtomicCounter::ValueType () const
{
        return _counter;
}

        
inline AtomicCounter::ValueType AtomicCounter::value() const
{
        return _counter;
}


inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
{
        return InterlockedIncrement(&_counter);
}

        
inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
{
        ValueType result(_counter);
        InterlockedIncrement(&_counter);
        return result;
}


inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
{
        return InterlockedDecrement(&_counter);
}

        
inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
{
        ValueType result(_counter);
        InterlockedDecrement(&_counter);
        return result;
}

        
inline bool AtomicCounter::operator ! () const
{
        return _counter == 0;
}


#elif POCO_OS == POCO_OS_MAC_OS_X
//
// Mac OS X
//
inline AtomicCounter::operator AtomicCounter::ValueType () const
{
        return _counter;
}

        
inline AtomicCounter::ValueType AtomicCounter::value() const
{
        return _counter;
}


inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
{
        return OSAtomicIncrement32(&_counter);
}

        
inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
{
        ValueType result(_counter);
        OSAtomicIncrement32(&_counter);
        return result;
}


inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
{
        return OSAtomicDecrement32(&_counter);
}

        
inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
{
        ValueType result(_counter);
        OSAtomicDecrement32(&_counter);
        return result;
}

        
inline bool AtomicCounter::operator ! () const
{
        return _counter == 0;
}


#else
//
// Generic implementation based on FastMutex
//
inline AtomicCounter::operator AtomicCounter::ValueType () const
{
        ValueType result;
        {
                FastMutex::ScopedLock lock(_counter.mutex);
                result = _counter.value;
        }
        return result;
}

        
inline AtomicCounter::ValueType AtomicCounter::value() const
{
        ValueType result;
        {
                FastMutex::ScopedLock lock(_counter.mutex);
                result = _counter.value;
        }
        return result;
}


inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
{
        ValueType result;
        {
                FastMutex::ScopedLock lock(_counter.mutex);
                result = ++_counter.value;
        }
        return result;
}

        
inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
{
        ValueType result;
        {
                FastMutex::ScopedLock lock(_counter.mutex);
                result = _counter.value++;
        }
        return result;
}


inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
{
        ValueType result;
        {
                FastMutex::ScopedLock lock(_counter.mutex);
                result = --_counter.value;
        }
        return result;
}

        
inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
{
        ValueType result;
        {
                FastMutex::ScopedLock lock(_counter.mutex);
                result = _counter.value--;
        }
        return result;
}

        
inline bool AtomicCounter::operator ! () const
{
        bool result;
        {
                FastMutex::ScopedLock lock(_counter.mutex);
                result = _counter.value == 0;
        }
        return result;
}


#endif // POCO_OS


} // namespace Poco


#endif // Foundation_AtomicCounter_INCLUDED