This sample text is one of the simplest examples of thread programming in C/C++ that I've ever seen - not that I've done that much looking. Taken from
Gregory R. Andrews's book. It is also, not a terrible example of split binary semaphores.
#include <pthread.h>
#include <semaphore.h>
#include <stdio.h> #define SHARED 1
void* producer( void* ); // The two threads
void* consumer( void* );sem_t empty, full;
int data;
int numIters;
int main( int argc, char* argv[] )
{
pthread_t pid, cid;
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM );
sem_init(&empty, SHARED, 1); // sem empty = 1
sem_init(&full, SHARED, 0 ); // sem full = 0 numIters = atoi( argv[1] ); pthread_create(&pid, &attr, producer, NULL );
pthread_create(&cid, &attr, consumer, NULL ); pthread_join(pid, NULL);
pthread_join(cid, NULL);
}
void* producer( void* argc)
{
int produced;
for( produced = 1; produced <= numIters; produced++)
{ sem_wait( &empty );
data = produced;
sem_post( &full );
}
}
void* consumer( void* argc)
{ int total = 0, consumed;
for( consumed = 1; consumed <= numIters; consumed++)
{ sem_wait( &full );
total += data;
sem_post( &empty);
}
printf( "the total is %d\n", total);
}
