source: tests/concurrency/pthread/bounded_buffer.cfa @ b2fa3c2

#include <stdlib.h>                                                                             // prototype: rand
#include <fstream.hfa>
#include <thread.hfa>
#include <pthread.h>
#include <errno.h>
// tested pthread mutex related routines, pthread cond related routines
// tested pthread_create/join

enum { BufferSize = 50 };

volatile int producer_val_total;
volatile int consumer_val_total;

pthread_mutex_t producer_cnt_lock, consumer_cnt_lock;


forall( T ){
    struct Buffer
    {
        int front, back, count;
                T elements[BufferSize];
        pthread_mutex_t _mutex;
            pthread_cond_t Full, Empty;                                                 // waiting consumers & producers
    };

    void ?{}( Buffer(T) & buffer ) with( buffer ) {
         [front, back, count] = 0; 
         pthread_mutex_init(&_mutex, NULL);
         pthread_cond_init(&Full, NULL);
         pthread_cond_init(&Empty, NULL);
    }

    void ^?{}( Buffer(T) & buffer ) with( buffer ){
        pthread_mutex_destroy(&_mutex);
        pthread_cond_destroy(&Full);
        pthread_cond_destroy(&Empty);
    }

    int query( Buffer(T) & buffer ) { return buffer.count; } // read-only, no mutual exclusion
    
    void insert( Buffer(T) & buffer, T elem ) with(buffer) {
                pthread_mutex_lock(&_mutex);
                while ( count == 20 ) pthread_cond_wait( &Empty, &_mutex ); // block producer
                elements[back] = elem;
                back = ( back + 1 ) % 20;
                count += 1;
                pthread_cond_signal( &Full );                                   // unblock consumer
        pthread_mutex_unlock(&_mutex);
        }

    T remove(Buffer(T) & buffer) with(buffer) {
                pthread_mutex_lock(&_mutex);
                while ( count == 0 ) pthread_cond_wait( &Full, &_mutex ); // block consumer
                T elem = elements[front];
                front = ( front + 1 ) % 20;
                count -= 1;
                pthread_cond_signal( &Empty );                                  // unblock producer
        pthread_mutex_unlock(&_mutex);
                return elem;
        }

}

void *producer( void *arg ) {
    Buffer(int) &buf = *(Buffer(int)*)arg;
        const int NoOfItems = prng(*active_thread(), 40);
        int item;
        for ( int i = 1; i <= NoOfItems; i += 1 ) {                     // produce a bunch of items
                item = prng(*active_thread(), 1, 101);                  // produce a random number
                //sout | "Producer:" | pthread_self() | " value:" | item;
                insert( buf,item );                                                             // insert element into queue
        pthread_mutex_lock(&producer_cnt_lock);
        producer_val_total += item;
        pthread_mutex_unlock(&producer_cnt_lock);
        } // for
        //sout | "Producer:" | pthread_self() | " is finished";
        return NULL;
} // producer

void *consumer( void *arg ) {
        Buffer(int) &buf = *(Buffer(int) *)arg;
        int item;
        for ( ;; ) {                                                                            // consume until a negative element appears
                item = remove(buf);                                                     // remove from front of queue
                //sout | "Consumer:" | pthread_self() | " value:" | item;
          if ( item == -1 ) break;
        pthread_mutex_lock(&consumer_cnt_lock);
        consumer_val_total += item;
        pthread_mutex_unlock(&consumer_cnt_lock);
        } // for
        //sout | "Consumer:" | pthread_self() | " is finished";
        return NULL;
} // consumer

int main() {
        const int NoOfCons = 20, NoOfProds = 30;
        Buffer(int) buf;                                                                // create a buffer monitor
        pthread_t cons[NoOfCons];                                                       // pointer to an array of consumers
        pthread_t prods[NoOfProds];                                                     // pointer to an array of producers
    pthread_mutex_init(&producer_cnt_lock, NULL);
    pthread_mutex_init(&consumer_cnt_lock, NULL);
        // parallelism
    set_seed( 1003 );

        processor p[5];
    {
        // create/join and mutex/condition test
        //sout | "create/join and mutex/condition test";
        for ( int i = 0; i < NoOfCons; i += 1 ) {                       // create consumers
            if ( pthread_create( &cons[i], NULL, consumer, (void*)&buf ) != 0 ) {
                sout | "create thread failure, errno:" | errno;
                exit( EXIT_FAILURE );
            } // if
        } // for
        for ( int i = 0; i < NoOfProds; i += 1 ) {                      //      create producers
            if ( pthread_create( &prods[i], NULL, producer, (void*)&buf ) != 0 ) {
                sout | "create thread failure";
                exit( EXIT_FAILURE );
            } // if
        } // for

        void *result;
        for ( int i = 0; i < NoOfProds; i += 1 ) {                      // wait for producers to end
            if ( pthread_join( prods[i], &result ) != 0 ) {
                sout | " producers join thread failure";
                exit( EXIT_FAILURE );
            } // if
            if ( (uint64_t)result != 0 ) {
                sout | "producers" | prods[i] |" bad return value " | result;
                exit( EXIT_FAILURE );
            } // if
            //sout | "join prods[" | i | "]:" | prods[i] | " result:" | result;
        } // for

        for ( int i = 0; i < NoOfCons; i += 1 ) {                       // terminate each consumer
            insert(buf, -1 );
        } // for

        for ( int i = 0; i < NoOfCons; i += 1 ) {                       // wait for consumer to end
            if ( pthread_join( cons[i], &result ) != 0 ) {
                sout| "consumers join thread failure" ;
                exit( EXIT_FAILURE );
            } // if
            if ( (uint64_t)result != 0 ) {
                sout| "consumers bad return value" | result;
                exit( EXIT_FAILURE );
            } // if
        } // for
        sout | "producer total value is " | producer_val_total;
        sout | "consumer total value is " | consumer_val_total;
    }

        

        
}