shared_mutex
- shared_mutex::lock()用法同mutex::lock()
- shared_mutex::lock_shared()允许多线程同时进入临界区，只用用于只读场景，不然是线程不安全的
- shared_mutex::lock_shared()与shared_mutex::lock()互斥，不能同时上锁
#include <shared_mutex>
#include <iostream>
#include <thread>
using namespace std;
shared_mutex m;
int share_counter{0};
void increment1(int target)
{
for (int i = 0; i < target; i++)
{
m.lock();
share_counter++;
m.unlock();
}
}
void increment2(int target)
{
for (int i = 0; i < target; i++)
{
m.lock_shared();
share_counter++;
m.unlock_shared();
}
}
using incre_fun = void(int);
void test_increment(int target, incre_fun fun)
{
share_counter = 0;
thread t1(fun, target);
thread t2(fun, target);
t1.join();
t2.join();
cout << "Count result: " << share_counter << endl;
}
void test_increment2(int target, incre_fun fun1, incre_fun fun2)
{
share_counter = 0;
thread t1(fun1, target);
thread t2(fun2, target);
t1.join();
t2.join();
cout << "Count result: " << share_counter << endl;
}
void SharedMutexTest()
{
test_increment(1000000, increment1); // Count result: 2000000
test_increment(1000000, increment2); // Count result: 1906613
test_increment2(1000000, increment1, increment2); // Count result: 2000000
}