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
(none).
Notes
unlock()
is usually not called directly: std::unique_lock
and std::lock_guard
are used to manage exclusive locking.
Example
This example shows lock
, try_lock
and unlock
in action:
#include <iostream> #include <mutex> int main() { std::mutex test; if (test.try_lock()) { std::cout << "first try_lock successful\n"; } else { std::cout << "first try_lock NOT successful\n"; return 0; } test.unlock(); test.lock(); if (test.try_lock()) { std::cout << "second try_lock successful\n"; } else { std::cout << "second try_lock NOT successful\n"; } test.lock(); // trying to lock an already-locked std::mutex will // block program execution, so we'll hang here }
Possible output:
first try_lock successful second try_lock NOT successful (program hangs)
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) |
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