Sean Mooney
72132f89ee
This change improves FairLockGuard to properly support two previously
unsupported (or broken) usage patterns:
1. Cross-thread sharing: When threads share the same FairLockGuard
instance, they now correctly wait for each other instead of raising
TypeError. Fixed by:
- Adding _active_thread tracking to identify the owning thread
- Restructuring lock acquisition order: named locks are now acquired
OUTSIDE of locks_lock to prevent deadlock when Thread-B waits on
locks held by Thread-A
- Only same-thread re-entry triggers the nesting logic, not
cross-thread access
2. Same-thread nesting: The same FairLockGuard instance can now be
nested within itself. Fixed by:
- Adding _nesting_depth counter initialized to 0
- Nested entries increment depth and return early (locks held)
- Exits decrement depth; locks only released when depth reaches 0
- This prevents lock leaks that would occur if inner exit cleared
self.locks before outer exit could release them
Additional improvements:
- Exception handling during partial lock acquisition now properly
releases any locks acquired before the failure
- Lock release moved outside locks_lock in __exit__ for consistency
The docstring has been updated to reflect that both patterns now work,
while continuing to discourage them in favor of creating separate
FairLockGuard instances for clarity.
New tests added:
- test_deep_nesting: Verifies 3+ levels of nesting
- test_nested_exception_outer_still_holds_locks: Verifies outer context
retains locks when inner context raises an exception
- test_empty_lock_list: Verifies empty lock list edge case
Related-Bug: #2048837
Generated-By: claude-code opus 4.5
Change-Id: Ia937b0e2d76c814360f168d5f33b821bfc61aade
Signed-off-by: Sean Mooney <work@seanmooney.info>
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