From 69a3928c4b3a8bd7b288b818fbbdccae5d22189f Mon Sep 17 00:00:00 2001
From: Adam Olley <adam.olley@openlms.net>
Date: Tue, 17 Aug 2021 11:13:18 +0930
Subject: [PATCH] Support custom locks

Without this - there is no way to define custom lock instances and the default
file locking is forced.

This lets you define your own:
```
$CFG->tool_forcedcache_config_array = [
  'locks' => [
    'muclock_default' => [
      'name' => 'Example custom lock',
      'type' => 'cachelock_file',
    ],
  ],
];
```
---
 classes/cache_config.php     | 41 +++++++++++++++++++++++++++---------
 lang/en/tool_forcedcache.php |  2 ++
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/classes/cache_config.php b/classes/cache_config.php
index deb4e5d..9ee89d9 100644
--- a/classes/cache_config.php
+++ b/classes/cache_config.php
@@ -113,7 +113,10 @@ private function generate_config_array(): array {
         }
 
         // Generate locks.
-        $locks = $this->generate_locks();
+        if (!isset($config['locks'])) {
+            $config['locks'] = [];
+        }
+        $locks = $this->generate_locks($config['locks']);
 
         // Get the siteidentifier. Copies pattern from cache_config.
         // Uses 'forcedcache' if not known.
@@ -387,15 +390,33 @@ private function generate_definition_mappings_from_rules(array $rules, array $de
      *
      * @return array array of locks to use.
      */
-    private function generate_locks() : array {
-        return array(
-            'default_file_lock' => array(
-                'name' => 'cachelock_file_default',
-                'type' => 'cachelock_file',
-                'dir' => 'filelocks',
-                'default' => true
-            )
-        );
+    private function generate_locks(array $locks) : array {
+        if (empty($locks)) {
+            return array(
+                'default_file_lock' => array(
+                    'name' => 'cachelock_file_default',
+                    'type' => 'cachelock_file',
+                    'dir' => 'filelocks',
+                    'default' => true
+                )
+            );
+        }
+
+        foreach ($locks as $key => $lock) {
+            // First check that all the required fields are present in the lock.
+            if (!(array_key_exists('name', $lock) || array_key_exists('type', $lock))) {
+                throw new cache_exception(get_string('lock_missing_fields', 'tool_forcedcache', $key));
+            }
+
+            // Then check the lock plugins exist.
+            $pluginname = substr($lock['type'], 10);
+            $cachepath = __DIR__.'/../../../../cache/locks/' . $pluginname . '/lib.php';
+            if (!file_exists($cachepath)) {
+                throw new cache_exception(get_string('lock_bad_type', 'tool_forcedcache', $pluginname));
+            }
+        }
+
+        return $locks;
     }
 
     /**
diff --git a/lang/en/tool_forcedcache.php b/lang/en/tool_forcedcache.php
index 5196819..ef69ac5 100644
--- a/lang/en/tool_forcedcache.php
+++ b/lang/en/tool_forcedcache.php
@@ -33,6 +33,8 @@
 $string['config_json_missing'] = 'Error reading specified JSON file. File may not exist, or path is incorrect.';
 $string['config_path_and_array'] = 'Detected both path to file and config array. Only one can be specified.';
 $string['definition_not_found'] = 'Definition not defined for configuration override: {$a}.';
+$string['lock_bad_type'] = 'Error loading lock {$a}. Lock may not exist or type is malformed.';
+$string['lock_missing_fields'] = 'Error reading lock {$a}, it may be missing field or malformed.';
 $string['store_missing_fields'] = 'Error reading store {$a}, it may be missing fields or malformed.';
 $string['store_bad_type'] = 'Error loading store {$a}. Store may not exist or type is malformed.';
 $string['store_not_ready'] = 'Error creating store {$a}, config may be incorrect or missing required fields.';