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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, the behavior is undefined.

[edit] Parameters

[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>
 
using namespace std::chrono_literals;
 
std::mutex cout_mutex; // control access to std::cout
std::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();
}

[0] failed failed failed 
[3] failed failed success 
[2] failed success failed 
[1] success failed success

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also

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