template< class Rep, class Period > bool try_lock_for( const std::chrono::duration<Rep,Period>& timeout_duration ); | (since C++11) |
Tries to lock the mutex. Blocks until specified timeout_duration
has elapsed or the lock is acquired, 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()
.
A steady clock is used to measure the duration. This function may block for longer than timeout_duration
due to scheduling or resource contention delays.
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
, the behavior is undefined.
Parameters
timeout_duration | - | maximum duration to block for |
Return value
true
if the lock was acquired successfully, otherwise false
.
Exceptions
Any exception thrown by clock, time_point, or duration during the execution (clocks, time points, and durations provided by the standard library never throw).
Example
#include <iostream> #include <mutex> #include <thread> #include <vector> #include <sstream> std::mutex cout_mutex; // control access to std::cout std::timed_mutex mutex; void job(int id) { using Ms = std::chrono::milliseconds; std::ostringstream stream; for (int i = 0; i < 3; ++i) { if (mutex.try_lock_for(Ms(100))) { stream << "success "; std::this_thread::sleep_for(Ms(100)); mutex.unlock(); } else { stream << "failed "; } std::this_thread::sleep_for(Ms(100)); } 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& i: threads) { i.join(); } }
Possible output:
[0] failed failed failed [3] failed failed success [2] failed success failed [1] success failed success
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) |
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