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std::mutex::try_lock(3)        C++ Standard Libary	 std::mutex::try_lock(3)

NAME
     std::mutex::try_lock - std::mutex::try_lock

Synopsis
	bool try_lock();  (since C++11)

	Tries  to lock the mutex. Returns immediately. On successful lock acqui-
     sition returns
	true, otherwise returns false.

	This function is allowed to fail spuriously and return false even if the
     mutex is
	not currently locked by any other thread.

	If try_lock is called by a thread that already owns the mutex,	the  be-
     havior is
	undefined.

	Prior unlock() operation on the same mutex synchronizes-with (as defined
     in
	std::memory_order)  this  operation  if it returns true. Note that prior
     lock() does
	not synchronize with this operation if it returns false.

Parameters
	(none)

Return value
	true if the lock was acquired successfully, otherwise false.

Exceptions
	Throws nothing.

Example
     // Run this code

      #include <chrono>
      #include <iostream> // std::cout
      #include <mutex>
      #include <thread>

      std::chrono::milliseconds interval(100);

      std::mutex mutex;
      int job_shared = 0; // both threads can modify 'job_shared',
			  // mutex will protect this variable

      int job_exclusive = 0; // only one thread can modify 'job_exclusive'
			     // no protection needed

      // this thread can modify both 'job_shared' and 'job_exclusive'
      void job_1()
      {
	  std::this_thread::sleep_for(interval); // let 'job_2' take a lock

	  while (true)
	  {
	      // try to lock mutex to modify 'job_shared'
	      if (mutex.try_lock())
	      {
		  std::cout << "job shared (" << job_shared << ")\n";
		  mutex.unlock();
		  return;
	      }
	      else
	      {
		  // can't get lock to modify 'job_shared'
		  // but there is some other work to do
		  ++job_exclusive;
		  std::cout << "job exclusive (" << job_exclusive << ")\n";
		  std::this_thread::sleep_for(interval);
	      }
	  }
      }

      // this thread can modify only 'job_shared'
      void job_2()
      {
	  mutex.lock();
	  std::this_thread::sleep_for(5 * interval);
	  ++job_shared;
	  mutex.unlock();
      }

      int main()
      {
	  std::thread thread_1(job_1);
	  std::thread thread_2(job_2);

	  thread_1.join();
	  thread_2.join();
      }

Possible output:
      job exclusive (1)
      job exclusive (2)
      job exclusive (3)
      job exclusive (4)
      job shared (1)

See also
	lock   locks the mutex, blocks if the mutex is not available
	       (public member function)
	unlock unlocks the mutex
	       (public member function)
	C documentation for
	mtx_trylock

http://cppreference.com 	   2024.06.10		 std::mutex::try_lock(3)
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