多线程编程：用互斥锁同步资源(pthread_mutex_lock测试加锁)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <errno.h>
pthread_mutex_t mutex_x= PTHREAD_MUTEX_INITIALIZER;
int total_ticket_num=20;
void *sell_ticket1(void *arg){
    int iRet=0;
    for(int i=0;i<20;i++){
        iRet=pthread_mutex_trylock(&mutex_x);
        if(iRet==EBUSY&&total_ticket_num>0){
            printf ("sell_ticket1:the variable is locked by sell_ticket2.\n");
        }else if(iRet==0){
            if(total_ticket_num>0){
                printf("thread1 sell the %dth ticket\n",20-total_ticket_num+1);
                total_ticket_num--;
            }
            pthread_mutex_unlock(&mutex_x);
        }
        sleep(1);
    }
    return 0;
}
void *sell_ticket2(void *arg){
    int iRet=0;
    for(int i=0;i<20;i++){
        iRet=pthread_mutex_trylock(&mutex_x);
        if(iRet==EBUSY&&total_ticket_num>0){
            printf ("sell_ticket2:the variable is locked by sell_ticket1.\n");
        }else if(iRet==0){
            if(total_ticket_num>0){
                printf("thread2 sell the %dth ticket\n",20-total_ticket_num+1);
                total_ticket_num--;
            }
            pthread_mutex_unlock(&mutex_x);
        }
        sleep(1);
    }
    return 0;
}

int main(){
    pthread_t tids[2];
    int iRet = pthread_create(&tids[0], NULL, &sell_ticket1, NULL);
    if(iRet){
        printf("pthread_create error, iRet=%d\n",iRet);
        return iRet;
    }
    iRet = pthread_create(&tids[1], NULL, &sell_ticket2, NULL);
    if(iRet){
        printf("pthread_create error, iRet=%d\n",iRet);
        return iRet;
    }
    sleep(30);
    void *retval;
    iRet=pthread_join(tids[0], &retval);
    if(iRet){
        printf("tid=%d join error, iRet=%d\n",(int)tids[0],iRet);
    }else{
        printf("retval=%ld\n",(long*)retval);
    }
    iRet=pthread_join(tids[1], &retval);
    if(iRet){
        printf("tid=%d join error, iRet=%d\n",(int)tids[1],iRet);
    }else{
        printf("retval=%ld\n",(long*)retval);
    }
    return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.6)
project(pthread_mutex)

set(CMAKE_CXX_STANDARD 11)

set(SOURCE_FILES mutex.cpp)

add_executable(pthread_mutex ${SOURCE_FILES})
target_link_libraries(pthread_mutex -lpthread)