std::mutex::unlock
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std::mutex
Member functions
Locking
mutex::unlock
Native handle
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.
[edit] Notes
unlock() is usually not called directly: std::unique_lock and std::lock_guard are used to manage exclusive locking.
[edit] 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
[edit] See also
C documentation for mtx_unlock