std::shared_timed_mutex::try_lock_for
template<class Rep, class Period > bool try_lock_for(conststd::chrono::duration<Rep, Period>& timeout_duration ); | (since C++14) | |
Tries to lock the mutex. Blocks until the specified duration timeout_duration has elapsed (timeout) or the lock is acquired (owns the mutex), whichever comes first. On successful lock acquisition returns true, otherwise returns false.
If timeout_duration is less or equal timeout_duration.zero(), the function behaves like try_lock().
This function may block for longer than timeout_duration due to scheduling or resource contention delays.
The standard recommends that a std::steady_clock is used to measure the duration. If an implementation uses a std::system_clock instead, the wait time may also be sensitive to clock adjustments.
As with try_lock(), this function is allowed to fail spuriously and return false even if the mutex was not locked by any other thread at some point during timeout_duration.
Prior unlock() operation on the same mutex synchronizes-with (as defined in std::memory_order) this operation if it returns true.
If try_lock_for is called by a thread that already owns the mutex in any mode (shared or exclusive), the behavior is undefined.
Contents |
[edit]Parameters
| timeout_duration | - | minimum duration to block for |
[edit]Return value
true if the lock was acquired successfully, otherwise false.
[edit]Exceptions
Any exception thrown by timeout_duration (durations provided by the standard library never throw).
[edit]Example
#include <chrono>#include <iostream>#include <mutex>#include <sstream>#include <thread>#include <vector> usingnamespace std::chrono_literals; std::mutex cout_mutex;// control access to std::coutstd::timed_mutex mutex; void job(int id){std::ostringstream stream; for(int i =0; i <3;++i){if(mutex.try_lock_for(100ms)){ stream <<"success ";std::this_thread::sleep_for(100ms); mutex.unlock();}else stream <<"failed "; std::this_thread::sleep_for(100ms);} std::lock_guard<std::mutex> lock{cout_mutex};std::cout<<'['<< id <<"] "<< stream.str()<<'\n';} int main(){std::vector<std::thread> threads;for(int i{0}; i <4;++i) threads.emplace_back(job, i); for(auto& th : threads) th.join();}
Possible output:
[0] failed failed failed [3] failed failed success [2] failed success failed [1] success failed success
[edit]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) | |
| tries to lock the mutex, returns if the mutex has been unavailable until specified time point has been reached (public member function) | |
| unlocks the mutex (public member function) |
