std::mutex::unlock
From cppreference.com
| void unlock(); |
(since C++11) | |
Unlocks the mutex.
The mutex must be locked by the current thread of execution, otherwise, the behavior is undefined.
This operation synchronizes-with (as defined in std::memory_order) any subsequent lock operation that obtains ownership of the same mutex.
Parameters
(none)
Return value
(none)
Exceptions
Throws nothing.
Notes
unlock() is usually not called directly: std::unique_lock and std::lock_guard are used to manage exclusive locking.
Example
This example shows how lock and unlock can be used to protect shared data.
Run this code
#include <chrono> #include <iostream> #include <mutex> #include <thread> int g_num = 0; // protected by g_num_mutex std::mutex g_num_mutex; void slow_increment(int id) { for (int i = 0; i < 3; ++i) { g_num_mutex.lock(); int g_num_running = ++g_num; g_num_mutex.unlock(); std::cout << id << " => " << g_num_running << '\n'; std::this_thread::sleep_for(std::chrono::seconds(1)); } } int main() { std::thread t1(slow_increment, 0); std::thread t2(slow_increment, 1); t1.join(); t2.join(); }
Possible output:
0 => 1 1 => 2 0 => 3 1 => 4 0 => 5 1 => 6
See also
| locks the mutex, blocks if the mutex is not available (public member function) | |
| tries to lock the mutex, returns if the mutex is not available (public member function) | |
| C documentation for mtx_unlock
| |