【thread】shared_mutex

std::shared_mutex

1. 原型：

1）测试用例：

#include <iostream>
#include <mutex>
#include <shared_mutex>
#include <thread>

class ThreadSafeCounter {
 public:
  ThreadSafeCounter() = default;

  unsigned int get() const {
    std::shared_lock lock(mutex_);
    return value_;
  }

  unsigned int increment() {
    std::unique_lock lock(mutex_);
    return ++value_;
  }

  void reset() {
    std::unique_lock lock(mutex_);
    value_ = 0;
  }

 private:
  mutable std::shared_mutex mutex_;
  unsigned int value_ = 0;
};

int main() {
  ThreadSafeCounter counter;

  auto increment_and_print = [&counter]() {
    for (int i = 0; i < 3; i++) {
      std::cout << std::this_thread::get_id() << "-" << counter.increment() << std::endl;
    }
  };

  std::thread thread1(increment_and_print);
  std::thread thread2(increment_and_print);

  thread1.join();
  thread2.join();
}

 1 #include <iostream>
 2 #include <mutex>
 3 #include <shared_mutex>
 4 #include <thread>
 5  
 6 class ThreadSafeCounter {
 7  public:
 8   ThreadSafeCounter() = default;
 9  
10   unsigned int get() const {
11     std::shared_lock lock(mutex_);
12     return value_;
13   }
14  
15   unsigned int increment() {
16     std::unique_lock lock(mutex_);
17     return ++value_;
18   }
19  
20   void reset() {
21     std::unique_lock lock(mutex_);
22     value_ = 0;
23   }
24  
25  private:
26   mutable std::shared_mutex mutex_;
27   unsigned int value_ = 0;
28 };
29  
30 int main() {
31   ThreadSafeCounter counter;
32  
33   auto increment_and_print = [&counter]() {
34     for (int i = 0; i < 3; i++) {
35       std::cout << std::this_thread::get_id() << "-" << counter.increment() << std::endl;
36     }
37   };
38  
39   std::thread thread1(increment_and_print);
40   std::thread thread2(increment_and_print);
41  
42   thread1.join();
43   thread2.join();
44 }

输出：

2. 测试用例

 1 #include <iostream>
 2 #include <mutex>
 3 #include <shared_mutex>
 4 #include <thread>
 5 
 6 std::shared_mutex g_mutex;
 7 std::string g_str;
 8 
 9 void readLoop() {
10   while (true) {
11     std::this_thread::sleep_for(chrono::milliseconds(100));
12     g_mutex.lock_shared();
13     std::cout << g_str;
14     g_mutex.unlock_shared();
15   }
16 }
17 
18 void writeLoop() {
19   int number = 0;
20   while (true) {
21     stgd::this_thread::sleep_for(chrono::milliseconds(100));
22     g_mutex.lock();
23     g_str = to_string(number++) + "\n";
24     g_mutex.unlock();
25   }
26 }
27 
28 int main() {
29   std::thread t1(writeLoop);
30   std::thread t2(readLoop);
31   std::thread t3(readLoop);
32 
33   t1.join();
34   t2.join();
35   t3.join();
36 }

2）测试用例

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原文地址：https://www.cnblogs.com/sunbines/p/16153021.html