std::recursive_timed_mutex::try_lock_for (3) - Linux Manuals

std::recursive_timed_mutex::try_lock_for: std::recursive_timed_mutex::try_lock_for

NAME

std::recursive_timed_mutex::try_lock_for - std::recursive_timed_mutex::try_lock_for

Synopsis

template< class Rep, class Period > (since C++11)
bool try_lock_for( const std::chrono::duration<Rep,Period>& timeout_duration );

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().
This function may block for longer than timeout_duration due to scheduling or resource contention delays.
The standard recommends that a steady_clock is used to measure the duration. If an implementation uses a 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.
A thread may call try_lock_for on a recursive mutex repeatedly. Successful calls to try_lock_for increment the ownership count: the mutex will only be released after the thread makes a matching number of calls to unlock.
The maximum number of levels of ownership is unspecified. A call to try_lock_for will return false if this number is exceeded.

Parameters

timeout_duration - minimum 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

// Run this code

  #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