genesis-3d_engine/Engine/foundation/threading/safequeue.h

#pragma once
/****************************************************************************
Copyright (c) 2007, Radon Labs GmbH
Copyright (c) 2011-2013,WebJet Business Division,CYOU
 
http://www.genesis-3d.com.cn

Permission is hereby granted, free of charge, to any person obtaining a copy
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The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
****************************************************************************/

#include "util/queue.h"
#include "threading/criticalsection.h"
#include "threading/event.h"

//------------------------------------------------------------------------------
namespace Threading
{
template<class TYPE> class SafeQueue : protected Util::Queue<TYPE>
{
public:
    /// constructor
    SafeQueue();
    /// copy constructor
    SafeQueue(const SafeQueue<TYPE>& rhs);

    /// assignment operator
    void operator=(const SafeQueue<TYPE>& rhs);
    /// enable/disable signalling on Enqueue() (default is enabled)
    void SetSignalOnEnqueueEnabled(bool b);
    /// return signalling-on-Enqueue() flag
    bool IsSignalOnEnqueueEnabled() const;
    /// returns number of elements in the queue
    SizeT Size() const;
    /// return true if queue is empty
    bool IsEmpty() const;
    /// remove all elements from the queue
    void Clear();
    /// add element to the back of the queue
    void Enqueue(const TYPE& e);
    /// enqueue an array of elements
    void EnqueueArray(const Util::Array<TYPE>& a);
    /// remove the element from the front of the queue
    TYPE Dequeue();
    /// dequeue all events (only requires one lock)
    void DequeueAll(Util::Array<TYPE>& outArray);
	/// dequeue all events by swap(only requires one lock)
	void DequeueAllBySwap(Util::Array<TYPE>& outArray);

    /// access to element at front of queue without removing it
    TYPE Peek() const;
    /// wait until queue contains at least one element
    void Wait();
    /// wait until queue contains at least one element, or time-out happens
    void WaitTimeout(int ms);
    /// signal the internal event, so that Wait() will return
    void Signal();
    /// erase all matching elements
    void EraseMatchingElements(const TYPE& e);

protected:
    CriticalSection criticalSection;
    Event enqueueEvent;
    bool signalOnEnqueueEnabled;
};

//------------------------------------------------------------------------------
/**
*/
template<class TYPE>
SafeQueue<TYPE>::SafeQueue() :
    signalOnEnqueueEnabled(true)
{
    // empty
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE>
SafeQueue<TYPE>::SafeQueue(const SafeQueue<TYPE>& rhs)
{
    this->criticalSection.Enter();
    this->queueArray = rhs.queueArray;
    this->signalOnEnqueueEnabled = rhs.signalOnEnqueueEnabled;
    this->criticalSection.Leave();
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::operator=(const SafeQueue<TYPE>& rhs)
{
    this->criticalSection.Enter();
    this->queueArray = rhs.queueArray;
    this->signalOnEnqueueEnabled = rhs.signalOnEnqueueEnabled;
    this->criticalSection.Leave();
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::SetSignalOnEnqueueEnabled(bool b)
{
    this->criticalSection.Enter();
    this->signalOnEnqueueEnabled = b;
    this->criticalSection.Leave();
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::Clear()
{
    this->criticalSection.Enter();
    this->queueArray.Clear();
    this->criticalSection.Leave();
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> SizeT
SafeQueue<TYPE>::Size() const
{
    return this->queueArray.Size();
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> bool
SafeQueue<TYPE>::IsEmpty() const
{
    this->criticalSection.Enter();
    bool isEmpty = this->queueArray.IsEmpty();
    this->criticalSection.Leave();
    return isEmpty;
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::Enqueue(const TYPE& e)
{
    this->criticalSection.Enter();
    this->queueArray.Append(e);
    this->criticalSection.Leave();
    if (this->signalOnEnqueueEnabled)
    {
        this->enqueueEvent.Signal();
    }
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::EnqueueArray(const Util::Array<TYPE>& a)
{
    this->criticalSection.Enter();
    this->queueArray.AppendArray(a);
    this->criticalSection.Leave();
    if (this->signalOnEnqueueEnabled)
    {
        this->enqueueEvent.Signal();
    }
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> TYPE
SafeQueue<TYPE>::Dequeue()
{
    this->criticalSection.Enter();
    TYPE e = this->queueArray.Front();
    this->queueArray.EraseIndex(0);
    this->criticalSection.Leave();
    return e;
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::DequeueAll(Util::Array<TYPE>& outArray)
{
    this->criticalSection.Enter();
    outArray = this->queueArray;
    this->queueArray.Clear();
    this->criticalSection.Leave();
}
//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
	SafeQueue<TYPE>::DequeueAllBySwap(Util::Array<TYPE>& outArray)
{
	this->criticalSection.Enter();
	outArray.Swap(this->queueArray);
	this->criticalSection.Leave();
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> TYPE
SafeQueue<TYPE>::Peek() const
{
    this->criticalSection.Enter();
    TYPE e = this->queueArray.Front();
    this->criticalSection.Leave();
    return e;
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::Wait()
{
    if (this->signalOnEnqueueEnabled && this->IsEmpty())
    {
        this->enqueueEvent.Wait();
    }
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::WaitTimeout(int ms)
{
    if (this->signalOnEnqueueEnabled && this->IsEmpty())
    {
        this->enqueueEvent.WaitTimeout(ms);
    }
}

//------------------------------------------------------------------------------
/**
    This signals the internal event object, on which Wait() may be waiting.
    This method may be useful to wake up a thread waiting for events
    when it should stop.
*/
template<class TYPE> void
SafeQueue<TYPE>::Signal()
{
    this->enqueueEvent.Signal();
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
SafeQueue<TYPE>::EraseMatchingElements(const TYPE& e)
{
    this->criticalSection.Enter();
    IndexT i;
    for (i = this->queueArray.Size() - 1; i >= 0; i--)
    {
        if (e == this->queueArray[i])
        {
            this->queueArray.EraseIndex(i);
        }
    }
    this->criticalSection.Leave();
}

} // namespace Threading
//------------------------------------------------------------------------------