tpie::queue< T > Class Template Reference

Basic Implementation of I/O Efficient FIFO queue. More...

#include <tpie/queue.h>

Public Member Functions
	queue (cache_hint cacheHint=access_sequential, compression_flags compressionFlags=compression_normal)
	Constructor for Temporary Queue. More...
bool	empty ()
	Check if the queue is empty. More...
stream_size_type	size ()
	Returns the number of items currently on the queue. More...
void	push (const T &t)
	Enqueue an item. More...
const T &	pop ()
	Dequeues an item. More...
const T &	front ()
	Returns at the frontmost item in the queue. More...

Static Public Member Functions
static memory_size_type	memory_usage (double blockFactor=1.0)
	Compute the memory used by the queue. More...

Detailed Description

template<class T>
class tpie::queue< T >

Basic Implementation of I/O Efficient FIFO queue.

The queue uses a pop stream, a center queue, and a push stream, to model a queue. The front elements of the queue are the pop stream items, followed by the center queue items, followed by the push stream items.

Elements are pushed to the center queue. When the center queue is full, subsequent pushed elements are written to the push stream.

Elements are popped from the pop stream. When this is empty, the center queue is used instead. When the center queue is also empty, the push stream and the pop stream are swapped.

Definition at line 53 of file queue.h.

Constructor & Destructor Documentation

template<class T >

tpie::queue< T >::queue ( cache_hint  cacheHint = access_sequential, compression_flags  compressionFlags = compression_normal  )

inline

Constructor for Temporary Queue.

Definition at line 58 of file queue.h.

        : m_size(0)
        , m_queueA(1.0)
        , m_queueB(1.0)
        , m_centerQueue(get_block_size()/sizeof(T))
        , m_currentQueue(true)
    {
        m_queueA.open(0, cacheHint, compressionFlags);
        m_queueB.open(0, cacheHint, compressionFlags);
    }

Member Function Documentation

template<class T >

bool tpie::queue< T >::empty ( )

inline

Check if the queue is empty.

Returns

true if the queue is empty otherwize false

Definition at line 74 of file queue.h.

{return m_size == 0;}

template<class T >

const T& tpie::queue< T >::front ( )

inline

Returns at the frontmost item in the queue.

Returns

The front most item in the queue

Definition at line 123 of file queue.h.

                      {
        if(pop_queue().can_read())
            return pop_queue().peek();
        else if(!m_centerQueue.empty())
            return m_centerQueue.front();
        else {
            swap_file_streams();
            return pop_queue().peek();
        }
    }

template<class T >

static memory_size_type tpie::queue< T >::memory_usage ( double  blockFactor = 1.0 )

inlinestatic

Compute the memory used by the queue.

Definition at line 137 of file queue.h.

                                                                 {
        return sizeof(queue<T>)
            + 3*file_stream<T>::memory_usage(blockFactor) - 2*sizeof(file_stream<T>);
    }

template<class T >

const T& tpie::queue< T >::pop ( )

inline

Dequeues an item.

Returns

The dequeued item

Definition at line 101 of file queue.h.

                    {
        --m_size;
        if(pop_queue().can_read()) {
            // The front of the queue is the pop stream
            return pop_queue().read();
        } else if (!m_centerQueue.empty()) {
            // The front of the queue is the center queue
            const T & i = m_centerQueue.front();
            m_centerQueue.pop();
            return i;
        } else {
            // The front of the queue is the push stream,
            // so we swap the push stream and the pop stream.
            swap_file_streams();
            return pop_queue().read();
        }
    }

template<class T >

void tpie::queue< T >::push ( const T &  t )

inline

Enqueue an item.

Parameters

t	The item to be enqueued

Definition at line 86 of file queue.h.

References tpie::queue< T >::size().

                                  {
        if (push_queue().size() == 0 && !m_centerQueue.full()) {
            // The back of the queue is the center queue
            m_centerQueue.push(t);
        } else {
            // The back of the queue is the push stream
            push_queue().write(t);
        }
        ++m_size;
    }

template<class T >

stream_size_type tpie::queue< T >::size ( )

inline

Returns the number of items currently on the queue.

Returns

Number of itmes in the queue

Definition at line 80 of file queue.h.

Referenced by tpie::queue< T >::push().

{return m_size;}

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The documentation for this class was generated from the following file:

• queue.h