Merge "Don't fallback from uk to ru"

[lhc/web/wiklou.git] / includes / dao / DBAccessObjectUtils.php

diff --git a/includes/dao/DBAccessObjectUtils.php b/includes/dao/DBAccessObjectUtils.php
index ad7804c..cc63446 100644 (file)
--- a/includes/dao/DBAccessObjectUtils.php
+++ b/includes/dao/DBAccessObjectUtils.php
@@ -26,7 +26,7 @@
  *
  * @since 1.26
  */
-class DBAccessObjectUtils {
+class DBAccessObjectUtils implements IDBAccessObject {
        /**
         * @param integer $bitfield
         * @param integer $flags IDBAccessObject::READ_* constant
@@ -37,23 +37,45 @@ class DBAccessObjectUtils {
        }
 
        /**
-        * Get an appropriate DB index and options for a query
+        * Get an appropriate DB index, options, and fallback DB index for a query
         *
-        * @param integer $bitfield
-        * @return array (DB_MASTER/DB_SLAVE, SELECT options array)
+        * The fallback DB index and options are to be used if the entity is not found
+        * with the initial DB index, typically querying the master DB to avoid lag
+        *
+        * @param integer $bitfield Bitfield of IDBAccessObject::READ_* constants
+        * @return array List of DB indexes and options in this order:
+        *   - DB_MASTER or DB_REPLICA constant for the initial query
+        *   - SELECT options array for the initial query
+        *   - DB_MASTER constant for the fallback query; null if no fallback should happen
+        *   - SELECT options array for the fallback query; empty if no fallback should happen
         */
        public static function getDBOptions( $bitfield ) {
-               $index = self::hasFlags( $bitfield, IDBAccessObject::READ_LATEST )
-                       ? DB_MASTER
-                       : DB_SLAVE;
+               if ( self::hasFlags( $bitfield, self::READ_LATEST_IMMUTABLE ) ) {
+                       $index = DB_REPLICA; // override READ_LATEST if set
+                       $fallbackIndex = DB_MASTER;
+               } elseif ( self::hasFlags( $bitfield, self::READ_LATEST ) ) {
+                       $index = DB_MASTER;
+                       $fallbackIndex = null;
+               } else {
+                       $index = DB_REPLICA;
+                       $fallbackIndex = null;
+               }
+
+               $lockingOptions = [];
+               if ( self::hasFlags( $bitfield, self::READ_EXCLUSIVE ) ) {
+                       $lockingOptions[] = 'FOR UPDATE';
+               } elseif ( self::hasFlags( $bitfield, self::READ_LOCKING ) ) {
+                       $lockingOptions[] = 'LOCK IN SHARE MODE';
+               }
 
-               $options = array();
-               if ( self::hasFlags( $bitfield, IDBAccessObject::READ_EXCLUSIVE ) ) {
-                       $options[] = 'FOR UPDATE';
-               } elseif ( self::hasFlags( $bitfield, IDBAccessObject::READ_LOCKING ) ) {
-                       $options[] = 'LOCK IN SHARE MODE';
+               if ( $fallbackIndex !== null ) {
+                       $options = []; // locks on DB_REPLICA make no sense
+                       $fallbackOptions = $lockingOptions;
+               } else {
+                       $options = $lockingOptions;
+                       $fallbackOptions = []; // no fallback
                }
 
-               return array( $index, $options );
+               return [ $index, $options, $fallbackIndex, $fallbackOptions ];
        }
 }