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<?php
#
# Copyright (C) 2003-2004 Brion Vibber <brion@pobox.com>
# http://www.mediawiki.org/
#
# 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
/**
* @defgroup Cache Cache
*
* @file
* @ingroup Cache
*/
/**
* interface is intended to be more or less compatible with
* the PHP memcached client.
*
* backends for local hash array and SQL table included:
* <code>
* $bag = new HashBagOStuff();
* $bag = new SqlBagOStuff(); # connect to db first
* </code>
*
* @ingroup Cache
*/
abstract class BagOStuff {
var $debugMode = false;
public function set_debug( $bool ) {
$this->debugMode = $bool;
}
/* *** THE GUTS OF THE OPERATION *** */
/* Override these with functional things in subclasses */
/**
* Get an item with the given key. Returns false if it does not exist.
* @param $key string
*/
abstract public function get( $key );
/**
* Set an item.
* @param $key string
* @param $value mixed
* @param $exptime int Either an interval in seconds or a unix timestamp for expiry
*/
abstract public function set( $key, $value, $exptime = 0 );
/*
* Delete an item.
* @param $key string
* @param $time int Amount of time to delay the operation (mostly memcached-specific)
*/
abstract public function delete( $key, $time = 0 );
public function lock( $key, $timeout = 0 ) {
/* stub */
return true;
}
public function unlock( $key ) {
/* stub */
return true;
}
public function keys() {
/* stub */
return array();
}
/* *** Emulated functions *** */
/* Better performance can likely be got with custom written versions */
public function get_multi( $keys ) {
$out = array();
foreach ( $keys as $key ) {
$out[$key] = $this->get( $key );
}
return $out;
}
public function set_multi( $hash, $exptime = 0 ) {
foreach ( $hash as $key => $value ) {
$this->set( $key, $value, $exptime );
}
}
public function add( $key, $value, $exptime = 0 ) {
if ( $this->get( $key ) == false ) {
$this->set( $key, $value, $exptime );
return true;
}
}
public function add_multi( $hash, $exptime = 0 ) {
foreach ( $hash as $key => $value ) {
$this->add( $key, $value, $exptime );
}
}
public function delete_multi( $keys, $time = 0 ) {
foreach ( $keys as $key ) {
$this->delete( $key, $time );
}
}
public function replace( $key, $value, $exptime = 0 ) {
if ( $this->get( $key ) !== false ) {
$this->set( $key, $value, $exptime );
}
}
public function incr( $key, $value = 1 ) {
if ( !$this->lock( $key ) ) {
return false;
}
$value = intval( $value );
$n = false;
if ( ( $n = $this->get( $key ) ) !== false ) {
$n += $value;
$this->set( $key, $n ); // exptime?
}
$this->unlock( $key );
return $n;
}
public function decr( $key, $value = 1 ) {
return $this->incr( $key, - $value );
}
public function debug( $text ) {
if ( $this->debugMode )
wfDebug( "BagOStuff debug: $text\n" );
}
/**
* Convert an optionally relative time to an absolute time
*/
protected function convertExpiry( $exptime ) {
if ( ( $exptime != 0 ) && ( $exptime < 3600 * 24 * 30 ) ) {
return time() + $exptime;
} else {
return $exptime;
}
}
}
/**
* Functional versions!
* This is a test of the interface, mainly. It stores things in an associative
* array, which is not going to persist between program runs.
*
* @ingroup Cache
*/
class HashBagOStuff extends BagOStuff {
var $bag;
function __construct() {
$this->bag = array();
}
protected function expire( $key ) {
$et = $this->bag[$key][1];
if ( ( $et == 0 ) || ( $et > time() ) ) {
return false;
}
$this->delete( $key );
return true;
}
function get( $key ) {
if ( !isset( $this->bag[$key] ) ) {
return false;
}
if ( $this->expire( $key ) ) {
return false;
}
return $this->bag[$key][0];
}
function set( $key, $value, $exptime = 0 ) {
$this->bag[$key] = array( $value, $this->convertExpiry( $exptime ) );
}
function delete( $key, $time = 0 ) {
if ( !isset( $this->bag[$key] ) ) {
return false;
}
unset( $this->bag[$key] );
return true;
}
function keys() {
return array_keys( $this->bag );
}
}
/**
* Class to store objects in the database
*
* @ingroup Cache
*/
class SqlBagOStuff extends BagOStuff {
var $lb, $db;
var $lastExpireAll = 0;
protected function getDB() {
global $wgDBtype;
if ( !isset( $this->db ) ) {
/* We must keep a separate connection to MySQL in order to avoid deadlocks
* However, SQLite has an opposite behaviour.
* @todo Investigate behaviour for other databases
*/
if ( $wgDBtype == 'sqlite' ) {
$this->db = wfGetDB( DB_MASTER );
} else {
$this->lb = wfGetLBFactory()->newMainLB();
$this->db = $this->lb->getConnection( DB_MASTER );
$this->db->clearFlag( DBO_TRX );
}
}
return $this->db;
}
public function get( $key ) {
# expire old entries if any
$this->garbageCollect();
$db = $this->getDB();
$row = $db->selectRow( 'objectcache', array( 'value', 'exptime' ),
array( 'keyname' => $key ), __METHOD__ );
if ( !$row ) {
$this->debug( 'get: no matching rows' );
return false;
}
$this->debug( "get: retrieved data; expiry time is " . $row->exptime );
if ( $this->isExpired( $row->exptime ) ) {
$this->debug( "get: key has expired, deleting" );
try {
$db->begin();
# Put the expiry time in the WHERE condition to avoid deleting a
# newly-inserted value
$db->delete( 'objectcache',
array(
'keyname' => $key,
'exptime' => $row->exptime
), __METHOD__ );
$db->commit();
} catch ( DBQueryError $e ) {
$this->handleWriteError( $e );
}
return false;
}
return $this->unserialize( $db->decodeBlob( $row->value ) );
}
public function set( $key, $value, $exptime = 0 ) {
$db = $this->getDB();
$exptime = intval( $exptime );
if ( $exptime < 0 ) $exptime = 0;
if ( $exptime == 0 ) {
$encExpiry = $this->getMaxDateTime();
} else {
if ( $exptime < 3.16e8 ) # ~10 years
$exptime += time();
$encExpiry = $db->timestamp( $exptime );
}
try {
$db->begin();
$db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
$db->insert( 'objectcache',
array(
'keyname' => $key,
'value' => $db->encodeBlob( $this->serialize( $value ) ),
'exptime' => $encExpiry
), __METHOD__ );
$db->commit();
} catch ( DBQueryError $e ) {
$this->handleWriteError( $e );
return false;
}
return true;
}
public function delete( $key, $time = 0 ) {
$db = $this->getDB();
try {
$db->begin();
$db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
$db->commit();
} catch ( DBQueryError $e ) {
$this->handleWriteError( $e );
return false;
}
return true;
}
public function incr( $key, $step = 1 ) {
$db = $this->getDB();
$step = intval( $step );
try {
$db->begin();
$row = $db->selectRow( 'objectcache', array( 'value', 'exptime' ),
array( 'keyname' => $key ), __METHOD__, array( 'FOR UPDATE' ) );
if ( $row === false ) {
// Missing
$db->commit();
return false;
}
$db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
if ( $this->isExpired( $row->exptime ) ) {
// Expired, do not reinsert
$db->commit();
return false;
}
$oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
$newValue = $oldValue + $step;
$db->insert( 'objectcache',
array(
'keyname' => $key,
'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
'exptime' => $row->exptime
), __METHOD__ );
$db->commit();
} catch ( DBQueryError $e ) {
$this->handleWriteError( $e );
return false;
}
return $newValue;
}
public function keys() {
$db = $this->getDB();
$res = $db->select( 'objectcache', array( 'keyname' ), false, __METHOD__ );
$result = array();
foreach ( $res as $row ) {
$result[] = $row->keyname;
}
return $result;
}
protected function isExpired( $exptime ) {
return $exptime != $this->getMaxDateTime() && wfTimestamp( TS_UNIX, $exptime ) < time();
}
protected function getMaxDateTime() {
if ( time() > 0x7fffffff ) {
return $this->getDB()->timestamp( 1 << 62 );
} else {
return $this->getDB()->timestamp( 0x7fffffff );
}
}
protected function garbageCollect() {
/* Ignore 99% of requests */
if ( !mt_rand( 0, 100 ) ) {
$now = time();
/* Avoid repeating the delete within a few seconds */
if ( $now > ( $this->lastExpireAll + 1 ) ) {
$this->lastExpireAll = $now;
$this->expireAll();
}
}
}
public function expireAll() {
$db = $this->getDB();
$now = $db->timestamp();
try {
$db->begin();
$db->delete( 'objectcache', array( 'exptime < ' . $db->addQuotes( $now ) ), __METHOD__ );
$db->commit();
} catch ( DBQueryError $e ) {
$this->handleWriteError( $e );
}
}
public function deleteAll() {
$db = $this->getDB();
try {
$db->begin();
$db->delete( 'objectcache', '*', __METHOD__ );
$db->commit();
} catch ( DBQueryError $e ) {
$this->handleWriteError( $e );
}
}
/**
* Serialize an object and, if possible, compress the representation.
* On typical message and page data, this can provide a 3X decrease
* in storage requirements.
*
* @param $data mixed
* @return string
*/
protected function serialize( &$data ) {
$serial = serialize( $data );
if ( function_exists( 'gzdeflate' ) ) {
return gzdeflate( $serial );
} else {
return $serial;
}
}
/**
* Unserialize and, if necessary, decompress an object.
* @param $serial string
* @return mixed
*/
protected function unserialize( $serial ) {
if ( function_exists( 'gzinflate' ) ) {
$decomp = @gzinflate( $serial );
if ( false !== $decomp ) {
$serial = $decomp;
}
}
$ret = unserialize( $serial );
return $ret;
}
/**
* Handle a DBQueryError which occurred during a write operation.
* Ignore errors which are due to a read-only database, rethrow others.
*/
protected function handleWriteError( $exception ) {
$db = $this->getDB();
if ( !$db->wasReadOnlyError() ) {
throw $exception;
}
try {
$db->rollback();
} catch ( DBQueryError $e ) {
}
wfDebug( __METHOD__ . ": ignoring query error\n" );
$db->ignoreErrors( false );
}
}
/**
* Backwards compatibility alias
*/
class MediaWikiBagOStuff extends SqlBagOStuff { }
/**
* This is a wrapper for APC's shared memory functions
*
* @ingroup Cache
*/
class APCBagOStuff extends BagOStuff {
public function get( $key ) {
$val = apc_fetch( $key );
if ( is_string( $val ) ) {
$val = unserialize( $val );
}
return $val;
}
public function set( $key, $value, $exptime = 0 ) {
apc_store( $key, serialize( $value ), $exptime );
return true;
}
public function delete( $key, $time = 0 ) {
apc_delete( $key );
return true;
}
public function keys() {
$info = apc_cache_info( 'user' );
$list = $info['cache_list'];
$keys = array();
foreach ( $list as $entry ) {
$keys[] = $entry['info'];
}
return $keys;
}
}
/**
* This is a wrapper for eAccelerator's shared memory functions.
*
* This is basically identical to the deceased Turck MMCache version,
* mostly because eAccelerator is based on Turck MMCache.
*
* @ingroup Cache
*/
class eAccelBagOStuff extends BagOStuff {
public function get( $key ) {
$val = eaccelerator_get( $key );
if ( is_string( $val ) ) {
$val = unserialize( $val );
}
return $val;
}
public function set( $key, $value, $exptime = 0 ) {
eaccelerator_put( $key, serialize( $value ), $exptime );
return true;
}
public function delete( $key, $time = 0 ) {
eaccelerator_rm( $key );
return true;
}
public function lock( $key, $waitTimeout = 0 ) {
eaccelerator_lock( $key );
return true;
}
public function unlock( $key ) {
eaccelerator_unlock( $key );
return true;
}
}
/**
* Wrapper for XCache object caching functions; identical interface
* to the APC wrapper
*
* @ingroup Cache
*/
class XCacheBagOStuff extends BagOStuff {
/**
* Get a value from the XCache object cache
*
* @param $key String: cache key
* @return mixed
*/
public function get( $key ) {
$val = xcache_get( $key );
if ( is_string( $val ) )
$val = unserialize( $val );
return $val;
}
/**
* Store a value in the XCache object cache
*
* @param $key String: cache key
* @param $value Mixed: object to store
* @param $expire Int: expiration time
* @return bool
*/
public function set( $key, $value, $expire = 0 ) {
xcache_set( $key, serialize( $value ), $expire );
return true;
}
/**
* Remove a value from the XCache object cache
*
* @param $key String: cache key
* @param $time Int: not used in this implementation
* @return bool
*/
public function delete( $key, $time = 0 ) {
xcache_unset( $key );
return true;
}
}
/**
* Cache that uses DBA as a backend.
* Slow due to the need to constantly open and close the file to avoid holding
* writer locks. Intended for development use only, as a memcached workalike
* for systems that don't have it.
*
* @ingroup Cache
*/
class DBABagOStuff extends BagOStuff {
var $mHandler, $mFile, $mReader, $mWriter, $mDisabled;
public function __construct( $dir = false ) {
global $wgDBAhandler;
if ( $dir === false ) {
global $wgTmpDirectory;
$dir = $wgTmpDirectory;
}
$this->mFile = "$dir/mw-cache-" . wfWikiID();
$this->mFile .= '.db';
wfDebug( __CLASS__ . ": using cache file {$this->mFile}\n" );
$this->mHandler = $wgDBAhandler;
}
/**
* Encode value and expiry for storage
*/
function encode( $value, $expiry ) {
# Convert to absolute time
$expiry = $this->convertExpiry( $expiry );
return sprintf( '%010u', intval( $expiry ) ) . ' ' . serialize( $value );
}
/**
* @return list containing value first and expiry second
*/
function decode( $blob ) {
if ( !is_string( $blob ) ) {
return array( null, 0 );
} else {
return array(
unserialize( substr( $blob, 11 ) ),
intval( substr( $blob, 0, 10 ) )
);
}
}
function getReader() {
if ( file_exists( $this->mFile ) ) {
$handle = dba_open( $this->mFile, 'rl', $this->mHandler );
} else {
$handle = $this->getWriter();
}
if ( !$handle ) {
wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
}
return $handle;
}
function getWriter() {
$handle = dba_open( $this->mFile, 'cl', $this->mHandler );
if ( !$handle ) {
wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
}
return $handle;
}
function get( $key ) {
wfProfileIn( __METHOD__ );
wfDebug( __METHOD__ . "($key)\n" );
$handle = $this->getReader();
if ( !$handle ) {
return null;
}
$val = dba_fetch( $key, $handle );
list( $val, $expiry ) = $this->decode( $val );
# Must close ASAP because locks are held
dba_close( $handle );
if ( !is_null( $val ) && $expiry && $expiry < time() ) {
# Key is expired, delete it
$handle = $this->getWriter();
dba_delete( $key, $handle );
dba_close( $handle );
wfDebug( __METHOD__ . ": $key expired\n" );
$val = null;
}
wfProfileOut( __METHOD__ );
return $val;
}
function set( $key, $value, $exptime = 0 ) {
wfProfileIn( __METHOD__ );
wfDebug( __METHOD__ . "($key)\n" );
$blob = $this->encode( $value, $exptime );
$handle = $this->getWriter();
if ( !$handle ) {
return false;
}
$ret = dba_replace( $key, $blob, $handle );
dba_close( $handle );
wfProfileOut( __METHOD__ );
return $ret;
}
function delete( $key, $time = 0 ) {
wfProfileIn( __METHOD__ );
wfDebug( __METHOD__ . "($key)\n" );
$handle = $this->getWriter();
if ( !$handle ) {
return false;
}
$ret = dba_delete( $key, $handle );
dba_close( $handle );
wfProfileOut( __METHOD__ );
return $ret;
}
function add( $key, $value, $exptime = 0 ) {
wfProfileIn( __METHOD__ );
$blob = $this->encode( $value, $exptime );
$handle = $this->getWriter();
if ( !$handle ) {
return false;
}
$ret = dba_insert( $key, $blob, $handle );
# Insert failed, check to see if it failed due to an expired key
if ( !$ret ) {
list( $value, $expiry ) = $this->decode( dba_fetch( $key, $handle ) );
if ( $expiry < time() ) {
# Yes expired, delete and try again
dba_delete( $key, $handle );
$ret = dba_insert( $key, $blob, $handle );
# This time if it failed then it will be handled by the caller like any other race
}
}
dba_close( $handle );
wfProfileOut( __METHOD__ );
return $ret;
}
function keys() {
$reader = $this->getReader();
$k1 = dba_firstkey( $reader );
if ( !$k1 ) {
return array();
}
$result[] = $k1;
while ( $key = dba_nextkey( $reader ) ) {
$result[] = $key;
}
return $result;
}
}