trylock

#include <pthread.h>
#include <iostream>
using namespace std;

pthread_mutex_t g_mutex = PTHREAD_MUTEX_INITIALIZER;

void testLock()
{
    int ret = pthread_mutex_trylock(&g_mutex);
    cout << "try lock:" << ret << endl;
    ret = pthread_mutex_unlock(&g_mutex);
    cout << "unlock:" << ret << endl;
}

int main()
{
    testLock();
    cout << "---------test lock twice---------" << endl;
    pthread_mutex_lock(&g_mutex);
    testLock();
    pthread_mutex_unlock(&g_mutex);
}

try lock:0
unlock:0
---------test lock twice---------
try lock:16
unlock:0