《C++（四）--线程同步》

简介

利用条件变量实现线程同步；

Example

读写变量同步：
写完变量后将标志位 ready 置为 true，读完变量后将ready 置为 false

#include <iostream>
#include <mutex>
#include <condition_variable>
#include <thread>
#include <chrono>

using namespace std;

condition_variable cv;
mutex m_mutex;

int i = 0;
bool ready = true;

void Add(){
	while(1){
		this_thread::sleep_for(chrono::milliseconds(500));
		unique_lock<mutex> lc(m_mutex);
		while(ready)
			cv.wait(lc);
		
		// cv.wait(lc,[]{return !ready;});

		//modify the data
		i++;
		ready = true;
		cv.notify_all();
	}
}

void Read(){
	while(1){
		this_thread::sleep_for(chrono::milliseconds(1));
		unique_lock<mutex> lc(m_mutex);
		while(!ready)
			cv.wait(lc);

		// cv.wait(lc,[]{return ready;});

		//Read the data
		cout<<i<<endl;
		ready = false;
		cv.notify_all();
	}
}

int main(int argc, char** argv)
{
	thread add(Add);
	thread read(Read);
	add.join();
	read.join();
	return 1;
}