In addition to the current self-consistency checks (recursive locking, lock ordering graph check), it might be useful to allow the developer to specify certain conditions that are checked every time a lock is being acquired. For example:

• when locking lock class A, lock class B must be already locked
• when locking lock class A, lock class B must not be already locked
• when locking lock class A, lock C must be already locked

In tricky code where the developer knows the desired relationship between different lock classes and locks.