33 Concurrency support library [thread]

33.6 Mutual exclusion [thread.mutex]

33.6.6 Generic locking algorithms [thread.lock.algorithm]

🔗
template<class L1, class L2, class... L3> int try_lock(L1&, L2&, L3&...);
1
#
Preconditions: Each template parameter type meets the Cpp17Lockable requirements.
[Note 1: 
The unique_lock class template meets these requirements when suitably instantiated.
— end note]
2
#
Effects: Calls try_lock() for each argument in order beginning with the first until all arguments have been processed or a call to try_lock() fails, either by returning false or by throwing an exception.
If a call to try_lock() fails, unlock() is called for all prior arguments with no further calls to try_lock().
3
#
Returns: -1 if all calls to try_lock() returned true, otherwise a zero-based index value that indicates the argument for which try_lock() returned false.
🔗
template<class L1, class L2, class... L3> void lock(L1&, L2&, L3&...);
4
#
Preconditions: Each template parameter type meets the Cpp17Lockable requirements.
[Note 2: 
The unique_lock class template meets these requirements when suitably instantiated.
— end note]
5
#
Effects: All arguments are locked via a sequence of calls to lock(), try_lock(), or unlock() on each argument.
The sequence of calls does not result in deadlock, but is otherwise unspecified.
[Note 3: 
A deadlock avoidance algorithm such as try-and-back-off can be used, but the specific algorithm is not specified to avoid over-constraining implementations.
— end note]
If a call to lock() or try_lock() throws an exception, unlock() is called for any argument that had been locked by a call to lock() or try_lock().