C++多线程编程

对全局数据线程同步

#ifndef THREAD_H#define THREAD_H#include <pthread.h>class Thread{public:    Thread();    int start();    int stop();    virtual void* run();    bool join();    const pthread_t& getID()const { return ntid; }    virtual ~Thread(){};private:    Thread(const Thread&);    static void* threadproc(void*);    pthread_t ntid;};

MyThread.h

#include <pthread.h>#include "Thread.h"Thread::Thread(){}void* Thread::run(){}int Thread::start(){return pthread_create(&this->ntid,0,threadproc,static_cast<void *>(this));        }int Thread::stop(){return pthread_cancel(this->getID());}bool Thread::join(){return pthread_join(this->getID(),0);}void* Thread::threadproc(void* a_param){Thread* pthread = static_cast<Thread *>(a_param);return pthread->run();

新建MyThread类，继承Thread

MyThread.h

#ifndef MYTHREAD_H#define MYTHREAD_H#include <string>#include "Thread.h"class MyThread:public Thread{public:MyThread(const int n,const char* aName):mCount(n),mName(aName){};virtual void* run();int setCount(const int n);int setName(const char* aName);private:    int mCount;    std::string mName;};

MyThread.cpp

#include <string>#include <stdio.h>#include <boost/thread/thread.hpp>#include "MyThread.h"void* MyThread::run() {    int sum = this->mCount*10;    for(int i = 0;i < sum ;i++)    {    printf("%2d,the name is %s;\t\n",i,this->mName.c_str());    }}int MyThread::setCount(const int n){    this->mCount = n;    return 0;}int MyThread::setName(const char* aName){    std::string aString(aName);    this->mName = aString;    return 0;

main.cpp

#include <stdio.h>#include "MyThread.h"int main(){    MyThread t1(15,"Thread 1");    MyThread t2(12,"Thread 2");    t1.start();    t2.start();    sleep(1);    return 0;}

添加互斥锁

修改MyThread.cpp

#include <string>#include <stdio.h>#include <boost/thread/thread.hpp>#include "MyThread.h"pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;//添加互斥量void* MyThread::run() {    pthread_mutex_lock(&mutex);  //加锁    int sum = this->mCount*10;    for(int i = 0;i < sum ;i++)    {    printf("%2d,the name is %s;\t\n",i,this->mName.c_str());    pthread_mutex_unlock(&mutex);  //解锁}int MyThread::setCount(const int n){    this->mCount = n;    return 0;}int MyThread::setName(const char* aName){    std::string aString(aName);    this->mName = aString;    return 0;}   

对私有数据线程同步

C++封装的概念使不同对象之间的私有数据不会交错，但是在遇见多线程的情况下，这些并不表明私有数据不需要加锁，因为可能涉及到类中不同的方法在同时访问或者修改数据。

main.cpp文件修改

#include <stdio.h>#include "MyThread.h"int main(){    MyThread t1(150,"Thread 1");    //MyThread t2(12,"Thread 2");    t1.start();    t1.setCount(12);    //t2.start();    sleep(1);    return 0; }

MyThread.cpp文件中run函数进行修改

#include <string>#include <stdio.h>#include <boost/thread/thread.hpp>#include "MyThread.h"void* MyThread::run() {    for(int i = 0;i < this->mCount*10000 ;i++){printf("%2d,the name is %s;\t\n",i,this->mName.c_str());}}int MyThread::setCount(const int n){    this->mCount = n;    return 0;}int MyThread::setName(const char* aName){    std::string aString(aName);    this->mName = aString;    return 0;}

为了解决上述问题，我们对MyThread.h MyThread.cpp以及main.cpp进行修改

MyThread.h

#ifndef MYTHREAD_H#define MYTHREAD_H#include <string>#include "Thread.h"class MyThread:public Thread{public:MyThread(const int n,const char* aName):mCount(n),mName(aName){    pthread_mutex_init(&mutex,NULL);}virtual void* run();int setCount(const int n);int setName(const char* aName);private:    int mCount;    std::string mName;    pthread_mutex_t mutex;};

MyThread.cpp

#include <string>#include <stdio.h>#include <boost/thread/thread.hpp>#include "MyThread.h"void* MyThread::run() {    pthread_mutex_lock(&mutex);    //int sum = this->mCount*10;    for(int i = 0;i < this->mCount*10000 ;i++)    {        printf("%2d,the name is %s;\t\n",i,this->mName.c_str());    }    pthread_mutex_unlock(&mutex);}int MyThread::setCount(const int n){    pthread_mutex_lock(&mutex);    this->mCount = n;    pthread_mutex_unlock(&mutex);    return 0;}int MyThread::setName(const char* aName){    std::string aString(aName);    this->mName = aString;}

main.cpp

#include <stdio.h>#include "MyThread.h"int main(){    MyThread t1(150,"Thread 1");    t1.start();    sleep(1);    t1.setCount(12);    t1.start();    return 0;}

C++多线程编程注意事项

1. 线程调用到函数在一个类中，那必须将该函数声明为静态函数函数。因为静态成员函数属于静态全局区，线程可以共享这个区域，故可以各自调用。
2. 线程调用过程中如何传入参数
3. 互斥锁的实现，全局变量互斥，私有成员变量互斥