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//
// AtomicCounter.h
//
// $Id: //poco/1.4/Foundation/include/Poco/AtomicCounter.h#8 $
//
// 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>
#elif ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 2) || __GNUC__ > 4) && (defined(__x86_64__) || defined(__i386__))
#if !defined(POCO_HAVE_GCC_ATOMICS) && !defined(POCO_NO_GCC_ATOMICS)
#define POCO_HAVE_GCC_ATOMICS
#endif
#elif ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 3) || __GNUC__ > 4)
#if !defined(POCO_HAVE_GCC_ATOMICS) && !defined(POCO_NO_GCC_ATOMICS)
#define POCO_HAVE_GCC_ATOMICS
#endif
#endif // POCO_OS
#include "Poco/Mutex.h"
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
/// - GCC 4.1+ (Intel platforms only)
{
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;
#elif defined(POCO_HAVE_GCC_ATOMICS)
typedef int 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 = InterlockedIncrement(&_counter);
return --result;
}
inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
{
return InterlockedDecrement(&_counter);
}
inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
{
ValueType result = 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 = OSAtomicIncrement32(&_counter);
return --result;
}
inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
{
return OSAtomicDecrement32(&_counter);
}
inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
{
ValueType result = OSAtomicDecrement32(&_counter);
return ++result;
}
inline bool AtomicCounter::operator ! () const
{
return _counter == 0;
}
#elif defined(POCO_HAVE_GCC_ATOMICS)
//
// GCC 4.1+ atomic builtins.
//
inline AtomicCounter::operator AtomicCounter::ValueType () const
{
return _counter;
}
inline AtomicCounter::ValueType AtomicCounter::value() const
{
return _counter;
}
inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
{
return __sync_add_and_fetch(&_counter, 1);
}
inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
{
return __sync_fetch_and_add(&_counter, 1);
}
inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
{
return __sync_sub_and_fetch(&_counter, 1);
}
inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
{
return __sync_fetch_and_sub(&_counter, 1);
}
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
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