std::unique_lock::lock

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< cpp‎ | thread‎ | unique lock
 
 
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void lock();
(C++11 起)

锁定关联互斥。等效地调用 mutex()->lock()

目录

[编辑] 参数

(无)

[编辑] 返回值

(无)

[编辑] 异常

  • 任何 mutex()->lock() 所抛的异常
  • 若无关联互斥,则为以 std::errc::operation_not_permitted 为错误码的 std::system_error
  • 若关联互斥已为此 unique_lock 所锁定(换言之, owns_lock 为 true ),则为以 std::errc::resource_deadlock_would_occur 为错误码的 std::system_error

[编辑] 示例

下列示例用 lock 重获得被解锁的互斥。

#include <mutex>
#include <thread>
#include <iostream>
#include <vector>
#include <chrono>
 
int main()
{
    int counter = 0;
    std::mutex counter_mutex;
    std::vector<std::thread> threads;
 
    auto worker_task = [&](int id) {
        std::unique_lock<std::mutex> lock(counter_mutex);
        ++counter;
        std::cout << id << ", initial counter: " << counter << '\n';
        lock.unlock();
 
        // 我们模拟昂贵操作时不保有锁
        std::this_thread::sleep_for(std::chrono::seconds(1));
 
        lock.lock();
        ++counter;
        std::cout << id << ", final counter: " << counter << '\n';
    };
 
    for (int i = 0; i < 10; ++i) threads.emplace_back(worker_task, i);
 
    for (auto &thread : threads) thread.join();
}

可能的输出:

0, initial counter: 1
1, initial counter: 2
2, initial counter: 3
3, initial counter: 4
4, initial counter: 5
5, initial counter: 6
6, initial counter: 7
7, initial counter: 8
8, initial counter: 9
9, initial counter: 10
6, final counter: 11
3, final counter: 12
4, final counter: 13
2, final counter: 14
5, final counter: 15
0, final counter: 16
1, final counter: 17
7, final counter: 18
9, final counter: 19
8, final counter: 20

[编辑] 参阅

尝试锁定关联互斥,若互斥不可用则返回
(公开成员函数) [编辑]
解锁关联互斥
(公开成员函数) [编辑]