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376 lines
8.3 KiB
C++
376 lines
8.3 KiB
C++
//
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// AtomicCounter.h
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//
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// $Id: //poco/1.4/Foundation/include/Poco/AtomicCounter.h#4 $
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//
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// Library: Foundation
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// Package: Core
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// Module: AtomicCounter
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//
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// Definition of the AtomicCounter class.
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//
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// Copyright (c) 2009, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// Permission is hereby granted, free of charge, to any person or organization
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// obtaining a copy of the software and accompanying documentation covered by
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// this license (the "Software") to use, reproduce, display, distribute,
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// execute, and transmit the Software, and to prepare derivative works of the
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// Software, and to permit third-parties to whom the Software is furnished to
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// do so, all subject to the following:
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//
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// The copyright notices in the Software and this entire statement, including
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// the above license grant, this restriction and the following disclaimer,
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// must be included in all copies of the Software, in whole or in part, and
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// all derivative works of the Software, unless such copies or derivative
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// works are solely in the form of machine-executable object code generated by
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// a source language processor.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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#ifndef Foundation_AtomicCounter_INCLUDED
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#define Foundation_AtomicCounter_INCLUDED
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#include "Poco/Foundation.h"
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#if POCO_OS == POCO_OS_WINDOWS_NT
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#include "Poco/UnWindows.h"
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#elif POCO_OS == POCO_OS_MAC_OS_X
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#include <libkern/OSAtomic.h>
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#elif ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 1) || __GNUC__ > 4) && (defined(__x86_64__) || defined(__i386__))
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#if !defined(POCO_HAVE_GCC_ATOMICS)
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#define POCO_HAVE_GCC_ATOMICS
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#endif
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#else
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#include "Poco/Mutex.h"
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#endif // POCO_OS
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namespace Poco {
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class Foundation_API AtomicCounter
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/// This class implements a simple counter, which
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/// provides atomic operations that are safe to
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/// use in a multithreaded environment.
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///
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/// Typical usage of AtomicCounter is for implementing
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/// reference counting and similar things.
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///
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/// On some platforms, the implementation of AtomicCounter
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/// is based on atomic primitives specific to the platform
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/// (such as InterlockedIncrement, etc. on Windows), and
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/// thus very efficient. On platforms that do not support
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/// atomic primitives, operations are guarded by a FastMutex.
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///
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/// The following platforms currently have atomic
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/// primitives:
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/// - Windows
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/// - Mac OS X
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/// - GCC 4.1+ (Intel platforms only)
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{
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public:
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typedef int ValueType; /// The underlying integer type.
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AtomicCounter();
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/// Creates a new AtomicCounter and initializes it to zero.
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explicit AtomicCounter(ValueType initialValue);
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/// Creates a new AtomicCounter and initializes it with
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/// the given value.
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AtomicCounter(const AtomicCounter& counter);
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/// Creates the counter by copying another one.
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~AtomicCounter();
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/// Destroys the AtomicCounter.
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AtomicCounter& operator = (const AtomicCounter& counter);
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/// Assigns the value of another AtomicCounter.
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AtomicCounter& operator = (ValueType value);
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/// Assigns a value to the counter.
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operator ValueType () const;
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/// Returns the value of the counter.
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ValueType value() const;
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/// Returns the value of the counter.
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ValueType operator ++ (); // prefix
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/// Increments the counter and returns the result.
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ValueType operator ++ (int); // postfix
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/// Increments the counter and returns the previous value.
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ValueType operator -- (); // prefix
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/// Decrements the counter and returns the result.
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ValueType operator -- (int); // postfix
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/// Decrements the counter and returns the previous value.
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bool operator ! () const;
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/// Returns true if the counter is zero, false otherwise.
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private:
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#if POCO_OS == POCO_OS_WINDOWS_NT
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typedef volatile LONG ImplType;
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#elif POCO_OS == POCO_OS_MAC_OS_X
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typedef int32_t ImplType;
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#elif defined(POCO_HAVE_GCC_ATOMICS)
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typedef int ImplType;
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#else // generic implementation based on FastMutex
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struct ImplType
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{
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mutable FastMutex mutex;
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volatile int value;
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};
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#endif // POCO_OS
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ImplType _counter;
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};
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//
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// inlines
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//
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#if POCO_OS == POCO_OS_WINDOWS_NT
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//
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// Windows
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//
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inline AtomicCounter::operator AtomicCounter::ValueType () const
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{
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return _counter;
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}
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inline AtomicCounter::ValueType AtomicCounter::value() const
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{
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return _counter;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
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{
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return InterlockedIncrement(&_counter);
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}
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inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
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{
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ValueType result = InterlockedIncrement(&_counter);
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return --result;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
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{
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return InterlockedDecrement(&_counter);
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}
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inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
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{
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ValueType result = InterlockedDecrement(&_counter);
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return ++result;
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}
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inline bool AtomicCounter::operator ! () const
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{
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return _counter == 0;
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}
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#elif POCO_OS == POCO_OS_MAC_OS_X
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//
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// Mac OS X
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//
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inline AtomicCounter::operator AtomicCounter::ValueType () const
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{
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return _counter;
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}
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inline AtomicCounter::ValueType AtomicCounter::value() const
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{
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return _counter;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
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{
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return OSAtomicIncrement32(&_counter);
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}
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inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
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{
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ValueType result = OSAtomicIncrement32(&_counter);
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return --result;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
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{
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return OSAtomicDecrement32(&_counter);
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}
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inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
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{
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ValueType result = OSAtomicDecrement32(&_counter);
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return ++result;
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}
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inline bool AtomicCounter::operator ! () const
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{
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return _counter == 0;
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}
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#elif defined(POCO_HAVE_GCC_ATOMICS)
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//
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// GCC 4.1+ atomic builtins.
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//
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inline AtomicCounter::operator AtomicCounter::ValueType () const
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{
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return _counter;
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}
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inline AtomicCounter::ValueType AtomicCounter::value() const
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{
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return _counter;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
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{
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return __sync_add_and_fetch(&_counter, 1);
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}
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inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
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{
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return __sync_fetch_and_add(&_counter, 1);
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}
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inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
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{
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return __sync_sub_and_fetch(&_counter, 1);
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}
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inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
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{
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return __sync_fetch_and_sub(&_counter, 1);
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}
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inline bool AtomicCounter::operator ! () const
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{
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return _counter == 0;
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}
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#else
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//
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// Generic implementation based on FastMutex
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//
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inline AtomicCounter::operator AtomicCounter::ValueType () const
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{
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ValueType result;
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{
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FastMutex::ScopedLock lock(_counter.mutex);
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result = _counter.value;
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}
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return result;
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}
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inline AtomicCounter::ValueType AtomicCounter::value() const
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{
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ValueType result;
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{
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FastMutex::ScopedLock lock(_counter.mutex);
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result = _counter.value;
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}
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return result;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
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{
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ValueType result;
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{
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FastMutex::ScopedLock lock(_counter.mutex);
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result = ++_counter.value;
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}
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return result;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
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{
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ValueType result;
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{
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FastMutex::ScopedLock lock(_counter.mutex);
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result = _counter.value++;
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}
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return result;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
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{
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ValueType result;
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{
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FastMutex::ScopedLock lock(_counter.mutex);
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result = --_counter.value;
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}
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return result;
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}
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inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
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{
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ValueType result;
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{
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FastMutex::ScopedLock lock(_counter.mutex);
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result = _counter.value--;
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}
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return result;
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}
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inline bool AtomicCounter::operator ! () const
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{
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bool result;
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{
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FastMutex::ScopedLock lock(_counter.mutex);
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result = _counter.value == 0;
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}
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return result;
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}
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#endif // POCO_OS
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} // namespace Poco
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#endif // Foundation_AtomicCounter_INCLUDED
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