.. currentmodule:: llvmlite.binding.ffi
.. function:: register_lock_callback(acq_fn, rel_fn) Register callback functions for lock acquire and release. ``acq_fn`` and ``exit_fn`` are callables that take no arguments.
.. function:: unregister_lock_callback(acq_fn, rel_fn) Remove the registered callback functions for lock acquire and release. The arguments are the same as used in ``register_lock_callback()``.