source: tests/concurrency/pthread/pthread_demo_lock.cfa@ cef5bfc

#include <fstream.hfa>
#include <thread.hfa>
/* 
    test pthread_mutex to provide mutual exclusion
    test pthread_mutex_trylock not block when lock is acquired by others; test pthread_mutex_trylock can acquire the lock
*/
volatile int cnt_nolock = 0;
volatile int cnt_lock = 0;
volatile int cnt_trylock = 0;
extern "C"{
    static pthread_mutex_t _mutex;
}

/* mutex pthread routine  */
// unlocked increnment
void* inc_unlock(void* cnt){
    for (int i = 0; i < (uint64_t)cnt; i++){
        cnt_nolock++;
    }   // for
    return NULL;
}   
// locked increment
void* inc_lock(void* cnt){
    pthread_mutex_lock(&_mutex);
    for (int i = 0; i < (uint64_t)cnt; i++){
        cnt_lock++;
    }   // for
    pthread_mutex_unlock(&_mutex);
    return NULL;
}

/* test lock vs unlock */
void test_unlock(){
    pthread_t threads[20];
    for (int i = 0; i < 20; i++){
        pthread_create(&threads[i], NULL, inc_unlock, (void*)100000000);
    }
    for (int i = 0; i < 20; i++){
        void * res = NULL;
        pthread_join(threads[i], &res);
    }
    sout | "unlock res is" | cnt_nolock;
    cnt_nolock = 0;
}
extern "C"{
    void test_lock(){
        pthread_mutex_init(&_mutex, NULL);
        pthread_t threads[20];
        for (int i = 0; i < 20; i++){
            
            pthread_create(&threads[i], NULL, inc_lock, (void*)100000000);
        }
        for (int i = 0; i < 20; i++){
            void * res = NULL;
            pthread_join(threads[i], &res);
        }
        sout | "lock res is" | cnt_lock;
        pthread_mutex_destroy(&_mutex);
        if (cnt_lock != 100000000 * 20) {
            sout | "pthread mutex not working";
            exit(1);
        }
        cnt_lock = 0;
    }
}


/* mutex trylock pthread routine  */
void* trylock_test2(void* arg){
    int res = pthread_mutex_trylock(&_mutex);
    sout | "in trylocktest2 res1 is" | res;
    res = pthread_mutex_trylock(&_mutex);
    sout | "in trylocktest2 res2 is" | res;
    pthread_mutex_lock(&_mutex);
    for (int i = 0; i < (uint64_t)arg; i++) cnt_trylock++;
    pthread_mutex_unlock(&_mutex);
    return NULL;
}

void* trylock_test1(void* arg){
    int res = pthread_mutex_trylock(&_mutex);
    sout | "in trylocktest1 res1 is" | res;
    res = pthread_mutex_trylock(&_mutex);
    sout | "in trylocktest1 res2 is" | res;
    pthread_t task2;
    pthread_create(&task2, NULL, trylock_test2, (void*)100000000);

    // inc cnt then release the lock
    for (int i = 0; i < (uint64_t)arg; i++) cnt_trylock++;
    pthread_mutex_unlock(&_mutex);
    pthread_mutex_unlock(&_mutex);
    void * dummy = NULL;
    pthread_join(task2, &dummy);
    sout | "cnt_trylock is " | cnt_trylock;
    return NULL;
}

// trylock test
void test_trylock(){
    pthread_mutex_init(&_mutex, NULL);
    pthread_t task1;
    pthread_create(&task1, NULL, trylock_test1, (void*)100000000);
    void * dummy = NULL;
    pthread_join(task1,&dummy);
    pthread_mutex_destroy(&_mutex);
    if (cnt_trylock != 100000000 * 2) {
        sout | "pthread try mutex not working";
        exit(1);
    }
    cnt_trylock = 0;
}



int main(int argc, char const *argv[])
{
    
    // compare unlock vs lock
    test_lock();
    // test trylock
    test_trylock();
    
    return 0;
}