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std::recurs...x::try_lock(3)   C++ Standard Libary  std::recurs...x::try_lock(3)

NAME
     std::recursive_mutex::try_lock - std::recursive_mutex::try_lock

Synopsis
	bool try_lock() noexcept;  (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.

	A thread may call try_lock on a recursive mutex  repeatedly.  Successful
     calls to
	try_lock  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 will
	return false if this number is exceeded.

	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 <iostream>
      #include <mutex>

      int main()
      {
	  std::recursive_mutex test;
	  if (test.try_lock())
	  {
	      std::cout << "lock acquired\n";
	      test.unlock();
	  }
	  else
	      std::cout << "lock not acquired\n";

	  test.lock();
	  // non-recursive mutex would return false from try_lock now
	  if (test.try_lock())
	  {
	      std::cout << "lock acquired\n";
	      test.unlock();
	  }
	  else
	      std::cout << "lock not acquired\n";

	  test.unlock();
      }

Output:
      lock acquired
      lock acquired

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::recurs...x::try_lock(3)
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