...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
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.
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.
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.