C++(14)：shared

C++14实现了读写锁：

通过shared_lock可以创建读锁

通过unique_lock可以创建写锁

多个读锁可以同时运行，但是如果写锁被加锁了，那么其他写锁或读锁都会被阻塞

#include 
#include 
#include 
#include 
using namespace std;

shared_timed_mutex sLock;
int data = 10;

unsigned long getTime()
{
	return chrono::system_clock::now().time_since_epoch().count()/chrono::system_clock::period::den;
}

void read_shared_data(int id)
{
	cout << getTime() << " thread "<< id << " begin" << endl;
	shared_lock slk(sLock);
	cout << getTime() << " thread " << id << " read data=" << data << endl;
}

int main()
{
	shared_lock slk(sLock);        //读锁加锁
	cout << getTime() << " shared_lock locked"< ulk(sLock);        //写锁加锁   
	cout << getTime() << " unique_lock locked"<