Release lock when deleting cache key

[mattwire]

Overview

I'm seeing SqlGroup: Failed to acquire lock on cache key. intermittently on a number of sites. I'm not able to trace the reason because it might happen once a day or less and the cause of the error is always the previous request - ie. the current request cannot get a lock because the previous request didn't release it.

Before

if CRM_Utils_Cache_SqlGroup::set() called with ttl<=0 cache key is deleted but lock is never released.

After

if CRM_Utils_Cache_SqlGroup::set() called with ttl<=0 cache key is deleted and lock is released.

Technical Details

You can see by tracing the function delete() that it performs various actions before returning but does not release the lock. The lock is only released at the bottom of the set() function but the code returns immediately after the call to delete and never reaches the lock release code.

Comments

[civibot]

(Standard links)

• If this is your first pull-request for CiviCRM, please browse CONTRIBUTING.md for information about the development and testing processes.
• If you are reviewing this pull-request, you may wish to consult the test sites and the Review Standards (long template, short template).

[seamuslee001]

This seems fine to me and tests have passed merging