AtomicCounter.h

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//
// AtomicCounter.h
//
// Library: Foundation
// Package: Core
// Module:  AtomicCounter
//
// Definition of the AtomicCounter class.
//
// Copyright (c) 2009, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
 
 
#ifndef Foundation_AtomicCounter_INCLUDED
#define Foundation_AtomicCounter_INCLUDED
 
 
#include "Poco/Foundation.h"
#include <atomic>
 
 
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 functionality.
{
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;
        /// Converts the AtomicCounter to ValueType.
 
    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:
    std::atomic<int> _counter;
};
 
 
//
// inlines
//
 
inline AtomicCounter::operator AtomicCounter::ValueType () const
{
    return _counter.load();
}
 
 
inline AtomicCounter::ValueType AtomicCounter::value() const
{
    return _counter.load();
}
 
 
inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix
{
    return ++_counter;
}
 
 
inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix
{
    return _counter++;
}
 
 
inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix
{
    return --_counter;
}
 
 
inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix
{
    return _counter--;
}
 
 
inline bool AtomicCounter::operator ! () const
{
    return _counter.load() == 0;
}
 
 
} // namespace Poco
 
 
#endif // Foundation_AtomicCounter_INCLUDED