public member function
<mutex>
template <class Rep, class Period> bool try_lock_for (const chrono::duration<Rep,Period>& rel_time);
Try to lock mutex during time span
Parameters
rel_time
The maximum time span during which the thread will block, waiting to acquire a lock.
duration is an object that represents a specific relative time.
Return value
true if the function succeeds in locking the managed timed mutex object.
false otherwise.
Example
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// unique_lock::try_lock_for example
#include <iostream> // std::cout
#include <chrono> // std::chrono::milliseconds
#include <thread> // std::thread
#include <mutex> // std::timed_mutex, std::unique_lock, std::defer_lock
std::timed_mutex mtx;
void fireworks () {
std::unique_lock<std::timed_mutex> lck(mtx,std::defer_lock);
// waiting to get a lock: each thread prints "-" every 200ms:
while (!lck.try_lock_for(std::chrono::milliseconds(200))) {
std::cout << "-";
}
// got a lock! - wait for 1s, then this thread prints "*"
std::this_thread::sleep_for(std::chrono::milliseconds(1000));
std::cout << "*\n";
}
int main ()
{
std::thread threads[10];
// spawn 10 threads:
for (int i=0; i<10; ++i)
threads[i] = std::thread(fireworks);
for (auto& th : threads) th.join();
return 0;
}
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Possible output (after around 10s, length of lines may vary slightly):
------------------------------------*
----------------------------------------*
-----------------------------------*
------------------------------*
-------------------------*
--------------------*
---------------*
----------*
-----*
*
|
Data races
The unique_lock object is accessed/modified.
The managed timed mutex object is accessed/modified as an atomic operation (causing no data races).
Exception safety
Basic guarantee: if an exception is thrown by this member function, the unique_lock object is left in a valid state.
If the call fails, a system_error exception is thrown:
An exception is also thrown if the call to try_lock_for on the managed timed mutex object fails, and on any other condition reported with such mechanism by the library implementation.