39.mutex 的lock_guard与unique

39.mutex 的lock_guard与unique_lock

 1 #include <iostream>
 2 #include <thread>
 3 #include <mutex>
 4 using namespace std;
 5 
 6 #define N 100000
 7 
 8 mutex g_mutex;
 9 
10 void add(int *p)
11 {
12     for (int i = 0; i < N; i++)
13     {
14         //拥有mutex所有权,自动加锁自动解锁,读取失败就会一直等待
15         //lock_guard<mutex> lgd(g_mutex);
16         //unique也能加锁,但是速度比较慢,根据块语句锁定,根据mutex属性能否加锁
17         unique_lock<mutex> ulk(g_mutex);
18         (*p)++;
19     }
20 }
21 
22 void main()
23 {
24     int a = 0;
25     thread t1(add, &a);
26     thread t2(add, &a);
27     t1.join();
28     t2.join();
29     cout << a << endl;
30     cin.get();
31 }