linux下锁的使用

利用pthread_mutex_lock

代码：

#include <iostream>
#include <pthread.h>
#include <unistd.h>

class Mutex
{
public:
    Mutex()
    {
        //设置递归属性
        pthread_mutexattr_t attr;
        pthread_mutexattr_init(&attr);
        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE_NP);
        pthread_mutex_init(&m_locker, &attr);
        pthread_mutexattr_destroy(&attr);
    }
    ~Mutex()
    {
        pthread_mutex_destroy(&m_locker);
    }
    //加锁
    bool Lock(bool block = true)
    {
        if (block)
        {
            pthread_mutex_lock(&m_locker);
            return true;
        }
        return (pthread_mutex_trylock(&m_locker) == 0);
    }
    //加锁
    bool Trylock()
    {
        return (pthread_mutex_trylock(&m_locker) == 0);
    }
    //解锁
    void Unlock()
    {
        pthread_mutex_unlock(&m_locker);
    }

private:
    pthread_mutex_t m_locker;
};

Mutex locker;
int jiu = 0;
//读操作
void *rthread (void *t)
{
    while (true)
    {
        locker.Lock();
        printf("hello read!\n");
        if (jiu)
        {
            printf ("read\n");
            jiu = 0;
        }
        locker.Unlock();
        sleep(1);
    }
}
//写操作
void *wthread (void *t)
{
    while (true)
    {
        locker.Lock();
        printf("hello write!\n");
        if (!jiu)
        {
            printf ("write\n");
            jiu = 1;
        }
        locker.Unlock();
        sleep(1);
    }
}

int main ()
{
    pthread_t id;
    long t = 0x123;
    pthread_attr_t attr;
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);//分离式线程
    pthread_create(&id, &attr, rthread, (void *)t);
    pthread_create(&id, &attr, wthread, (void *)t);
    sleep(60);
    return 0;
}

上面代码，大意是实现一个临界资源的读写操作，写与读不能冲突。线程创建部分，可参看Linux下的多线程编程

 

配置make编译文件：

创建src文件夹，将cpp文件放该文件夹下。在src文件夹同级目录下创建CMakeLists.txt文件，内容为：

cmake_minimum_required(VERSION 2.8)
PROJECT(thread)
SET(CMAKE_CXX_FLAGS "-DDEBUG -Wno-invalid-offsetof -Wno-deprecated -gdwarf-2 -g3 -std=c++0x -g")
AUX_SOURCE_DIRECTORY(src DIR_SRCS)
SET(THREAD ${DIR_SRCS})
ADD_EXECUTABLE(./bin ${THREAD})
TARGET_LINK_LIBRARIES(./bin pthread)

在终端，执行命令：

cmake .
make -j

也可以使用make -jn命令，其中n为cpu的核数。