cout << "counter--(decrement, before): " << counter << endl;
counter--; //等待signal激活后再执行
cout << "counter--(decrement, after): " << counter << endl;
pthread_mutex_unlock(&counter_lock);
return NULL;
}
void* increment_counter(void* argv)
{
cout << "counter(increment): " << counter << endl;
pthread_mutex_lock(&counter_lock);
if (counter == 0)
pthread_cond_signal(&counter_nonzero); //激活(signal)阻塞(wait)的线程(先执行完signal线程，然后再执行wait线程)
cout << "counter++(increment, before): " << counter << endl;
counter++;
cout << "counter++(increment, after): " << counter << endl;
pthread_mutex_unlock(&counter_lock);
return NULL;
}
//终端执行：$ g++ -o test_thread_cond1 test_thread_cond1.cpp -lpthread
// $ ./test_thread_cond1
5. test_thread_cond2.cpp：
#include <pthread.h>
#include <iostream>
#include <unistd.h>
using namespace std;
pthread_mutex_t counter_lock1, counter_lock2;
pthread_cond_t counter_nonzero1, counter_nonzero2;
int counter = 0;
void* decrement_increment_counter(void* argv);
int main()
{
cout << "counter: " << counter << endl;
pthread_mutex_init(&counter_lock1, NULL);
pthread_mutex_init(&counter_lock2, NULL);
pthread_cond_init(&counter_nonzero1, NULL);
pthread_cond_init(&counter_nonzero2, NULL);
pthread_t thd;
int ret = -1;
ret = pthread_create(&thd, NULL, decrement_increment_counter, NULL);
if (ret){
cout << "create thread1 fail" << endl;
return -1;
}
int counter = 0;
while (counter != 10) {
cout << "counter(main): " << counter << endl;
sleep(1);
counter++;
}
pthread_join(thd, NULL);
pthread_mutex_destroy(&counter_lock1);
pthread_mutex_destroy(&counter_lock2);
pthread_cond_destroy(&counter_nonzero1);
pthread_cond_destroy(&counter_nonzero2);
cout << "ok!" << endl;
}
void* decrement_increment_counter(void* argv)
{
cout << "start counter: " << counter << endl;
pthread_mutex_lock(&counter_lock1);
cout << "counter(decrement): " << counter << endl;
while (counter == 1)
pthread_cond_wait(&counter_nonzero1, &counter_lock1); //进入阻塞(wait)，等待激活(signal)
cout << "counter--(decrement, before): " << counter << endl;
counter--; //等待signal激活后再执行
cout << "counter--(decrement, after): " << counter << endl;
pthread_mutex_unlock(&counter_lock1);
pthread_mutex_lock(&counter_lock2);
cout << "counter(increment): " << counter << endl;
if (counter == 0)
pthread_cond_signal(&counter_nonzero2); //激活(signal)阻塞(wait)的线程(先执行完signal线程，然后再执行wait线程)
cout << "counter++(increment, before): " << counter << endl;
counter++;
cout << "counter++(increment, after): " << counter << endl;
pthread_mutex_unlock(&counter_lock2);
return NULL;
}
//终端执行：$ g++ -o test_thread_cond2 test_thread_cond2.cpp -lpthread
// $ ./test_thread_cond2