MDL-36120 cache: now uses sha1 and has an option for simple keys

cache/classes/definition.php

@@ -39,6 +39,11 @@ defined('MOODLE_INTERNAL') || die();
  *          [int] Sets the mode for the definition. Must be one of cache_store::MODE_*
  *
  * Optional settings:
+ *     + simplekeys
+ *          [bool] Set to true if your cache will only use simple keys for its items.
+ *          Simple keys consist of digits, underscores and the 26 chars of the english language. a-zA-Z0-9_
+ *          If true the keys won't be hashed before being passed to the cache store for gets/sets/deletes. It will be
+ *          better for performance and possible only becase we know the keys are safe.
  *     + simpledata
  *          [bool] If set to true we know that the data is scalar or array of scalar.
  *     + requireidentifiers
@@ -129,6 +134,12 @@ class cache_definition {
      */
     protected $area;
 
+    /**
+     * If set to true we know the keys are simple. a-zA-Z0-9_
+     * @var bool
+     */
+    protected $simplekeys = false;
+
     /**
      * Set to true if we know the data is scalar or array of scalar.
      * @var bool
@@ -289,6 +300,7 @@ class cache_definition {
         $area = (string)$definition['area'];
 
         // Set the defaults.
+        $simplekeys = false;
         $simpledata = false;
         $requireidentifiers = array();
         $requiredataguarantee = false;
@@ -306,6 +318,9 @@ class cache_definition {
         $mappingsonly = false;
         $invalidationevents = array();
 
+        if (array_key_exists('simplekeys', $definition)) {
+            $simplekeys = (bool)$definition['simplekeys'];
+        }
         if (array_key_exists('simpledata', $definition)) {
             $simpledata = (bool)$definition['simpledata'];
         }
@@ -410,6 +425,7 @@ class cache_definition {
         $cachedefinition->mode = $mode;
         $cachedefinition->component = $component;
         $cachedefinition->area = $area;
+        $cachedefinition->simplekeys = $simplekeys;
         $cachedefinition->simpledata = $simpledata;
         $cachedefinition->requireidentifiers = $requireidentifiers;
         $cachedefinition->requiredataguarantee = $requiredataguarantee;
@@ -515,6 +531,14 @@ class cache_definition {
         return $this->component;
     }
 
+    /**
+     * Returns the PARAM type that best describes the expected keys.
+     * @return bool
+     */
+    public function uses_simple_keys() {
+        return $this->simplekeys;
+    }
+
     /**
      * Returns the identifiers that are being used for this definition.
      * @return array