From 3353aecc8b633f7a54105586f45cbf31098a0e0f Mon Sep 17 00:00:00 2001
From: sam marshall <s.marshall@open.ac.uk>
Date: Wed, 4 Jan 2023 12:02:37 +0000
Subject: [PATCH] MDL-76791 core_cache: Locking breaks for multiple-identifiers
 store

Cache locking fails if the cache store supports multiple identifiers
(in core, the only two which do are cachestore_static and
cachestore_mongodb, so this is unlikely to cause severe problems).
---
 cache/classes/loaders.php  |  6 +++---
 cache/tests/cache_test.php | 24 ++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/cache/classes/loaders.php b/cache/classes/loaders.php
index 32ccdf16bae..e78697be15a 100644
--- a/cache/classes/loaders.php
+++ b/cache/classes/loaders.php
@@ -1679,7 +1679,7 @@ class cache_application extends cache implements cache_loader_with_locking {
         if ($this->get_loader() !== false) {
             $this->get_loader()->acquire_lock($key);
         }
-        $key = $this->parse_key($key);
+        $key = cache_helper::hash_key($key, $this->get_definition());
         $before = microtime(true);
         if ($this->nativelocking) {
             $lock = $this->get_store()->acquire_lock($key, $this->get_identifier());
@@ -1706,7 +1706,7 @@ class cache_application extends cache implements cache_loader_with_locking {
      *      someone else has the lock.
      */
     public function check_lock_state($key) {
-        $key = $this->parse_key($key);
+        $key = cache_helper::hash_key($key, $this->get_definition());
         if (!empty($this->locks[$key])) {
             return true; // Shortcut to save having to make a call to the cache store if the lock is held by this process.
         }
@@ -1726,7 +1726,7 @@ class cache_application extends cache implements cache_loader_with_locking {
      */
     public function release_lock($key) {
         $loaderkey = $key;
-        $key = $this->parse_key($key);
+        $key = cache_helper::hash_key($key, $this->get_definition());
         if ($this->nativelocking) {
             $released = $this->get_store()->release_lock($key, $this->get_identifier());
         } else {
diff --git a/cache/tests/cache_test.php b/cache/tests/cache_test.php
index 05242ef4f54..2ee1198f6fc 100644
--- a/cache/tests/cache_test.php
+++ b/cache/tests/cache_test.php
@@ -2111,6 +2111,30 @@ class cache_test extends \advanced_testcase {
         $this->assertFalse($cache->has('a'));
     }
 
+    /**
+     * The application locking feature should work with caches that support multiple identifiers
+     * (static cache and MongoDB with a specific setting).
+     *
+     * @covers \cache_application
+     */
+    public function test_application_locking_multiple_identifier_cache() {
+        // Get an arbitrary definition (modinfo).
+        $instance = cache_config_testing::instance(true);
+        $definitions = $instance->get_definitions();
+        $definition = \cache_definition::load('phpunit', $definitions['core/coursemodinfo']);
+
+        // Set up a static cache using that definition, wrapped in cache_application so we can do
+        // locking.
+        $store = new \cachestore_static('test');
+        $store->initialise($definition);
+        $cache = new cache_application($definition, $store);
+
+        // Test the three locking functions.
+        $cache->acquire_lock('frog');
+        $this->assertTrue($cache->check_lock_state('frog'));
+        $cache->release_lock('frog');
+    }
+
     /**
      * Test requiring a lock before attempting to set a key.
      *