text: //
  // AtomicCounter.h
  //
  // $Id: //poco/1.4/Foundation/include/Poco/AtomicCounter.h#1 $
  //
  // 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  LONG  ImplType;  // zach - removed "volatile" for CB compile issues
  #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
  