[ 2017-03-01, Kona ]

SG1 recommends: Close as NAD

Several participants voiced strong objections, based on either memory model issues or lock elision. No support. It is already possible to write a wrapper that explicitly tracks ownership for testing in the owning thread, which may have been part of the intent here.

[ 2010 Batavia ]

The Concurrency subgroup reviewed this issue and deemed it to be an extension to be handled after publishing C++0x.

[ Resolution proposed by ballot comment: ]

Add a member function:

bool is_locked() const;

to std::mutex and std::recursive_mutex. These functions return true if the current thread would not be able to obtain a mutex. These functions do not synchronize with anything (and, thus, can avoid a memory fence).

Addresses US-189

mutex and recursive_mutex should have an is_locked() member function. is_locked allows a user to test a lock without acquiring it and can be used to implement a lightweight try_try_lock.