fix: Skip refresh if already in progress or if lock is already held

[ntkathole]

What this PR does / why we need it:

This is the fix to prevent deadlocks on registry cache refresh.

• Used self._refresh_lock.acquire(blocking=False) to avoid infinite waiting and avoids releasing an unlocked lock.
• Fixed recursive calls by checking self._refresh_lock.locked() flag to prevent self.refresh() from calling itself indirectly.
• Handled exceptions by wrapping logic inside try to catch errors and always release locks.

Which issue(s) this PR fixes:

#4898

Tests:

# pytest sdk/python/tests/unit/infra/registry/test_registry.py -svv
sdk/python/tests/unit/infra/registry/test_registry.py::test_cache_expiry_triggers_refresh 02/20/2025 03:36:21 PM feast.infra.registry.caching_registry INFO: Registry cache expired, so refreshing
02/20/2025 03:36:21 PM feast.infra.registry.caching_registry INFO: Skipping refresh if already in progress
02/20/2025 03:36:21 PM feast.infra.registry.caching_registry INFO: Registry cache expired, so refreshing
02/20/2025 03:36:21 PM feast.infra.registry.caching_registry INFO: Skipping refresh if already in progress
PASSED
sdk/python/tests/unit/infra/registry/test_registry.py::test_skip_refresh_if_lock_held 02/20/2025 03:36:21 PM feast.infra.registry.caching_registry INFO: Skipping refresh if lock is already held by another thread
PASSED
==================================================== 2 passed in 0.01s ====================================================

[franciscojavierarceo]

it looks like CachingRegistry doesn't have tests anywhere at all. It'd be good to add some and start to catch some of this stuff.

Could you add a test under sdk/python/tests/units/infra/registry/test_registry.py?

[lokeshrangineni]

integration test failure seems to be legit. may be better to investigate.

[ntkathole]

it looks like CachingRegistry doesn't have tests anywhere at all. It'd be good to add some and start to catch some of this stuff.

Could you add a test under sdk/python/tests/units/infra/registry/test_registry.py?

Tests added.

[franciscojavierarceo]

Nice thanks for this!