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| Member functions | ||||
| Locking | ||||
unique_lock::try_lock | ||||
| Modifiers | ||||
| Observers | ||||
| Non-member functions | ||||
bool try_lock(); | (since C++11) | |
Tries to lock (i.e., takes ownership of) the associated mutex without blocking. Effectively callsmutex()->try_lock().
std::system_error is thrown if there is no associated mutex or if the mutex is already locked by thisstd::unique_lock.
Contents |
(none)
true if the ownership of the mutex has been acquired successfully,false otherwise.
try_lock, but a customLockable might).std::unique_lock,std::system_error with an error code ofstd::errc::resource_deadlock_would_occur.The following examples try to acquire a mutex that was locked and unlocked.
#include <chrono>#include <iostream>#include <mutex>#include <thread>#include <vector> usingnamespace std::chrono_literals; int main(){std::mutex counter_mutex;std::vector<std::thread> threads;using Id=int; auto worker_task=[&](Id id,std::chrono::seconds wait,std::chrono::seconds acquire){// wait for a few seconds before acquiring lock.std::this_thread::sleep_for(wait); std::unique_lock<std::mutex> lock(counter_mutex,std::defer_lock);if(lock.try_lock())std::cout<<'#'<< id<<", lock acquired.\n";else{std::cout<<'#'<< id<<", failed acquiring lock.\n";return;} // keep the lock for a while.std::this_thread::sleep_for(acquire); std::cout<<'#'<< id<<", releasing lock (via destructor).\n";}; threads.emplace_back(worker_task, Id{0}, 0s, 2s); threads.emplace_back(worker_task, Id{1}, 1s, 0s); threads.emplace_back(worker_task, Id{2}, 3s, 0s); for(auto& thread: threads) thread.join();}
Output:
#0, lock acquired.#1, failed acquiring lock.#0, releasing lock (via destructor).#2, lock acquired.#2, releasing lock (via destructor).
| locks (i.e., takes ownership of) the associated mutex (public member function)[edit] | |
| attempts to lock (i.e., takes ownership of) the associatedTimedLockable mutex, returns if the mutex has been unavailable for the specified time duration (public member function)[edit] | |
| tries to lock (i.e., takes ownership of) the associatedTimedLockable mutex, returns if the mutex has been unavailable until specified time point has been reached (public member function)[edit] | |
| unlocks (i.e., releases ownership of) the associated mutex (public member function)[edit] |
