A thread-safe, lock-free queue with non-blocking access. More...

#include <lfQueue.h>

Inheritance diagram for lunchbox::LFQueue< T >:

Collaboration diagram for lunchbox::LFQueue< T >:

Public Member Functions
	LFQueue (const int32_t size)
	Construct a new queue. More...

	~LFQueue ()
	Destruct this queue. More...

bool	isEmpty () const

void	clear ()
	Reset (empty) the queue. More...

void	resize (const int32_t size)
	Resize and reset the queue. More...

bool	pop (T &result)
	Retrieve and pop the front element from the queue. More...

bool	getFront (T &result)
	Retrieve the front element from the queue. More...

bool	push (const T &element)
	Push a new element to the back of the queue. More...

size_t	getCapacity () const

Detailed Description

template<typename T>
class lunchbox::LFQueue< T >

A thread-safe, lock-free queue with non-blocking access.

Typically used for caches and non-blocking communication between two threads.

Current implementation constraints:

One reader thread
One writer thread
Fixed maximum size (writes may fail)
Not copyable

Example:

/* Copyright (c) 2010-2011, Stefan Eilemann <eile@equalizergraphics.com>
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License version 2.1 as published
 * by the Free Software Foundation.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
#include <test.h>
#include <lunchbox/clock.h>
#include <lunchbox/lfQueue.h>
#include <lunchbox/thread.h>
#include <iostream>
#define RUNTIME 1000 /*ms*/
lunchbox::LFQueue< uint64_t > queue(1024);
class ReadThread : public lunchbox::Thread
{
public:
    virtual ~ReadThread() {}
    virtual void run()
        {
            uint64_t nOps = 0;
            uint64_t nEmpty = 0;
            uint64_t item = 0xffffffffffffffffull;
            lunchbox::Clock clock;
            while( clock.getTime64() < RUNTIME )
            {
                if( queue.getFront( item ))
                {
                    TEST( item == nOps );
                    uint64_t item2 = 0xffffffffffffffffull;
                    TEST( queue.pop( item2 ));
                    TEST( item2 == item );
                    ++nOps;
                }
                TEST( item + 1 == nOps );
                ++nEmpty;
            }
            const float time = clock.getTimef();
            std::cout << 2*nOps/time << " reads/ms, " << nEmpty/time
                      << " empty/ms" << std::endl;
        }
};
int main( int, char** )
{
    ReadThread reader;
    uint64_t nOps = 0;
    uint64_t nEmpty = 0;
    TEST( reader.start( ));
    lunchbox::Clock clock;
    while( clock.getTime64() < RUNTIME )
    {
        while( queue.push( nOps ))
            ++nOps;
        ++nEmpty;
    }
    const float time = clock.getTimef();
    TEST( reader.join( ));
    std::cout << nOps/time << " writes/ms, " << nEmpty/time << " full/ms"
              << std::endl;
    return EXIT_SUCCESS;
}

Definition at line 42 of file lfQueue.h.

Constructor & Destructor Documentation

template<typename T>

lunchbox::LFQueue< T >::LFQueue ( const int32_t size )

inlineexplicit

Construct a new queue.

Version: 1.0

Definition at line 46 of file lfQueue.h.

template<typename T>

lunchbox::LFQueue< T >::~LFQueue ( )

inline

Destruct this queue.

Version: 1.0

Definition at line 50 of file lfQueue.h.

Member Function Documentation

template<typename T >

void lunchbox::LFQueue< T >::clear ( )

Reset (empty) the queue.

Version: 1.0

Definition at line 20 of file lfQueue.ipp.

template<typename T>

size_t lunchbox::LFQueue< T >::getCapacity ( ) const

inline

Returns: the maximum number of elements held by the queue.

Version: 1.0

Definition at line 99 of file lfQueue.h.

template<typename T >

bool lunchbox::LFQueue< T >::getFront ( T & result )

Retrieve the front element from the queue.

Parameters

result the front value or unmodified

Returns: true if an element was placed in result, false if the queue is empty.

Version: 1.0

Definition at line 46 of file lfQueue.ipp.

template<typename T>

bool lunchbox::LFQueue< T >::isEmpty ( ) const

inline

Returns: true if the queue is empty, false otherwise.

Version: 1.0

Definition at line 53 of file lfQueue.h.

template<typename T >

bool lunchbox::LFQueue< T >::pop ( T & result )

Retrieve and pop the front element from the queue.

Parameters

result the front value or unmodified

Returns: true if an element was placed in result, false if the queue is empty.

Version: 1.0

Definition at line 35 of file lfQueue.ipp.

template<typename T >

bool lunchbox::LFQueue< T >::push ( const T & element )

Push a new element to the back of the queue.

Parameters

element the element to add.

Returns: true if the element was placed, false if the queue is full

Version: 1.0

Definition at line 56 of file lfQueue.ipp.

template<typename T >

void lunchbox::LFQueue< T >::resize ( const int32_t size )

Resize and reset the queue.

This method is not thread-safe. The queue has to be empty.

Version: 1.0

Definition at line 27 of file lfQueue.ipp.

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

Public Member Functions

Detailed Description

template<typename T> class lunchbox::LFQueue< T >

Constructor & Destructor Documentation

Member Function Documentation

template<typename T>
class lunchbox::LFQueue< T >