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diff --git a/www/wiki/includes/dao/DBAccessObjectUtils.php b/www/wiki/includes/dao/DBAccessObjectUtils.php
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+<?php
+/**
+ * This file contains database access object related constants.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Database
+ */
+
+/**
+ * Helper class for DAO classes
+ *
+ * @since 1.26
+ */
+class DBAccessObjectUtils implements IDBAccessObject {
+	/**
+	 * @param int $bitfield
+	 * @param int $flags IDBAccessObject::READ_* constant
+	 * @return bool Bitfield has flag $flag set
+	 */
+	public static function hasFlags( $bitfield, $flags ) {
+		return ( $bitfield & $flags ) == $flags;
+	}
+
+	/**
+	 * Get an appropriate DB index, options, and fallback DB index for a query
+	 *
+	 * 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 int $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 ) {
+		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';
+		}
+
+		if ( $fallbackIndex !== null ) {
+			$options = []; // locks on DB_REPLICA make no sense
+			$fallbackOptions = $lockingOptions;
+		} else {
+			$options = $lockingOptions;
+			$fallbackOptions = []; // no fallback
+		}
+
+		return [ $index, $options, $fallbackIndex, $fallbackOptions ];
+	}
+}