81 lines
2.7 KiB
PHP
81 lines
2.7 KiB
PHP
<?php
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/**
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* This file contains database access object related constants.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Database
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*/
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/**
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* Helper class for DAO classes
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*
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* @since 1.26
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*/
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class DBAccessObjectUtils implements IDBAccessObject {
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/**
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* @param int $bitfield
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* @param int $flags IDBAccessObject::READ_* constant
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* @return bool Bitfield has flag $flag set
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*/
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public static function hasFlags( $bitfield, $flags ) {
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return ( $bitfield & $flags ) == $flags;
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}
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/**
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* Get an appropriate DB index, options, and fallback DB index for a query
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*
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* The fallback DB index and options are to be used if the entity is not found
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* with the initial DB index, typically querying the primary DB to avoid lag
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*
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* @param int $bitfield Bitfield of IDBAccessObject::READ_* constants
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* @return array List of DB indexes and options in this order:
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* - DB_PRIMARY or DB_REPLICA constant for the initial query
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* - SELECT options array for the initial query
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* - DB_PRIMARY constant for the fallback query; null if no fallback should happen
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* - SELECT options array for the fallback query; empty if no fallback should happen
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*/
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public static function getDBOptions( $bitfield ) {
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if ( self::hasFlags( $bitfield, self::READ_LATEST_IMMUTABLE ) ) {
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$index = DB_REPLICA; // override READ_LATEST if set
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$fallbackIndex = DB_PRIMARY;
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} elseif ( self::hasFlags( $bitfield, self::READ_LATEST ) ) {
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$index = DB_PRIMARY;
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$fallbackIndex = null;
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} else {
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$index = DB_REPLICA;
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$fallbackIndex = null;
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}
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$lockingOptions = [];
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if ( self::hasFlags( $bitfield, self::READ_EXCLUSIVE ) ) {
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$lockingOptions[] = 'FOR UPDATE';
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} elseif ( self::hasFlags( $bitfield, self::READ_LOCKING ) ) {
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$lockingOptions[] = 'LOCK IN SHARE MODE';
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}
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if ( $fallbackIndex !== null ) {
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$options = []; // locks on DB_REPLICA make no sense
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$fallbackOptions = $lockingOptions;
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} else {
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$options = $lockingOptions;
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$fallbackOptions = []; // no fallback
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}
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return [ $index, $options, $fallbackIndex, $fallbackOptions ];
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}
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}
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