Part A
Put the attached file (testlock.php) in your moodle root.
Open 2 different browsers (not just windows of same browser) and load the testlock.php page in each.
When refreshed simultaneously - one window should get a lock and either hold it for 6 seconds, or exit without releasing the lock, the other window should either timeout after 3 seconds (if the first window held the lock) or get a lock as soon as the first window finishes.
Test this a few times and make sure both windows do not get a lock at the same time, and all attempts to get a lock either timeout after 3 seconds or succeed within that time. Also make sure that locks are auto-released at the end of the request always.
Part B
With Mysql as the DB and no setting for $CFG->lock_factory in config.php,
Repeat Part A
With Postgres as the DB and no setting for $CFG->lock_factory in config.php,
Repeat Part A
Set in config.php
$CFG->lock_factory = '\core\lock\db_row_lock_factory';
Repeat Part A
Set in config.php
$CFG->lock_factory = '\core\lock\file_lock_factory';
Repeat Part A
Run unit tests on mysql. (Just lib/tests/lock_test.php and lib/tests/lock_config_test.php)
Run unit tests on postgres. (Just lib/tests/lock_test.php and lib/tests/lock_config_test.php)
Sub-task
Major
MDL-41675 Convert MUC to use locking framework
MDL-67522 Config-dist refers to $CFG->lock_file_root but code uses $CFG->file_lock_root
MDL-21110 PHP locking class
