Boost C++ Libraries

Queue

The boost::lockfree::queue class implements a multi-writer/multi-reader queue. The following example shows how integer values are produced and consumed by 4 threads each:

#include <boost/lockfree/queue.hpp>
#include <boost/thread/thread.hpp>
#include <iostream>

#include <boost/atomic.hpp>

boost::atomic_int producer_count( 0 );
boost::atomic_int consumer_count( 0 );

boost::lockfree::queue< int > queue( 128 );

const int iterations            = 10000000;
const int producer_thread_count = 4;
const int consumer_thread_count = 4;

void producer( void )
{
    for ( int i = 0; i != iterations; ++i ) {
        int value = ++producer_count;
        while ( !queue.push( value ) )
            ;
    }
}

boost::atomic< bool > done( false );
void                  consumer( void )
{
    int value;
    while ( !done ) {
        while ( queue.pop( value ) )
            ++consumer_count;
    }

    while ( queue.pop( value ) )
        ++consumer_count;
}

int main( int argc, char* argv[] )
{
    using namespace std;
    cout << "boost::lockfree::queue is ";
    if ( !queue.is_lock_free() )
        cout << "not ";
    cout << "lockfree" << endl;

    boost::thread_group producer_threads, consumer_threads;

    for ( int i = 0; i != producer_thread_count; ++i )
        producer_threads.create_thread( producer );

    for ( int i = 0; i != consumer_thread_count; ++i )
        consumer_threads.create_thread( consumer );

    producer_threads.join_all();
    done = true;

    consumer_threads.join_all();

    cout << "produced " << producer_count << " objects." << endl;
    cout << "consumed " << consumer_count << " objects." << endl;
}

The program output is:

produced 40000000 objects.
consumed 40000000 objects.

Stack

The boost::lockfree::stack class implements a multi-writer/multi-reader stack. The following example shows how integer values are produced and consumed by 4 threads each:

#include <boost/lockfree/stack.hpp>
#include <boost/thread/thread.hpp>
#include <iostream>

#include <boost/atomic.hpp>

boost::atomic_int producer_count( 0 );
boost::atomic_int consumer_count( 0 );

boost::lockfree::stack< int > stack( 128 );

const int iterations            = 1000000;
const int producer_thread_count = 4;
const int consumer_thread_count = 4;

void producer( void )
{
    for ( int i = 0; i != iterations; ++i ) {
        int value = ++producer_count;
        while ( !stack.push( value ) )
            ;
    }
}

boost::atomic< bool > done( false );

void consumer( void )
{
    int value;
    while ( !done ) {
        while ( stack.pop( value ) )
            ++consumer_count;
    }

    while ( stack.pop( value ) )
        ++consumer_count;
}

int main( int argc, char* argv[] )
{
    using namespace std;
    cout << "boost::lockfree::stack is ";
    if ( !stack.is_lock_free() )
        cout << "not ";
    cout << "lockfree" << endl;

    boost::thread_group producer_threads, consumer_threads;

    for ( int i = 0; i != producer_thread_count; ++i )
        producer_threads.create_thread( producer );

    for ( int i = 0; i != consumer_thread_count; ++i )
        consumer_threads.create_thread( consumer );

    producer_threads.join_all();
    done = true;

    consumer_threads.join_all();

    cout << "produced " << producer_count << " objects." << endl;
    cout << "consumed " << consumer_count << " objects." << endl;
}

The program output is:

produced 4000000 objects.
consumed 4000000 objects.

Waitfree Single-Producer/Single-Consumer Queue

The boost::lockfree::spsc_queue class implements a wait-free single-producer/single-consumer queue. The following example shows how integer values are produced and consumed by 2 separate threads:

#include <boost/lockfree/spsc_queue.hpp>
#include <boost/thread/thread.hpp>
#include <iostream>

#include <boost/atomic.hpp>

int               producer_count = 0;
boost::atomic_int consumer_count( 0 );

boost::lockfree::spsc_queue< int, boost::lockfree::capacity< 1024 > > spsc_queue;

const int iterations = 10000000;

void producer( void )
{
    for ( int i = 0; i != iterations; ++i ) {
        int value = ++producer_count;
        while ( !spsc_queue.push( value ) )
            ;
    }
}

boost::atomic< bool > done( false );

void consumer( void )
{
    int value;
    while ( !done ) {
        while ( spsc_queue.pop( value ) )
            ++consumer_count;
    }

    while ( spsc_queue.pop( value ) )
        ++consumer_count;
}

int main( int argc, char* argv[] )
{
    using namespace std;
    cout << "boost::lockfree::queue is ";
    if ( !spsc_queue.is_lock_free() )
        cout << "not ";
    cout << "lockfree" << endl;

    boost::thread producer_thread( producer );
    boost::thread consumer_thread( consumer );

    producer_thread.join();
    done = true;
    consumer_thread.join();

    cout << "produced " << producer_count << " objects." << endl;
    cout << "consumed " << consumer_count << " objects." << endl;
}

The program output is:

produced 10000000 objects.
consumed 10000000 objects.