Update and fixes.

[mediawiki.git] / includes / BagOStuff.php

<?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();
 *   $bag = new MediaWikiBagOStuff($tablename); # connect to db first
 * </code>
 *
 * @ingroup Cache
 */
class BagOStuff {
        var $debugmode;

        function __construct() {
                $this->set_debug( false );
        }

        function set_debug($bool) {
                $this->debugmode = $bool;
        }

        /* *** THE GUTS OF THE OPERATION *** */
        /* Override these with functional things in subclasses */

        function get($key) {
                /* stub */
                return false;
        }

        function set($key, $value, $exptime=0) {
                /* stub */
                return false;
        }

        function delete($key, $time=0) {
                /* stub */
                return false;
        }

        function lock($key, $timeout = 0) {
                /* stub */
                return true;
        }

        function unlock($key) {
                /* stub */
                return true;
        }

        function keys() {
                /* stub */
                return array();
        }

        /* *** Emulated functions *** */
        /* Better performance can likely be got with custom written versions */
        function get_multi($keys) {
                $out = array();
                foreach($keys as $key)
                        $out[$key] = $this->get($key);
                return $out;
        }

        function set_multi($hash, $exptime=0) {
                foreach($hash as $key => $value)
                        $this->set($key, $value, $exptime);
        }

        function add($key, $value, $exptime=0) {
                if( $this->get($key) == false ) {
                        $this->set($key, $value, $exptime);
                        return true;
                }
        }

        function add_multi($hash, $exptime=0) {
                foreach($hash as $key => $value)
                        $this->add($key, $value, $exptime);
        }

        function delete_multi($keys, $time=0) {
                foreach($keys as $key)
                        $this->delete($key, $time);
        }

        function replace($key, $value, $exptime=0) {
                if( $this->get($key) !== false )
                        $this->set($key, $value, $exptime);
        }

        function incr($key, $value=1) {
                if ( !$this->lock($key) ) {
                        return false;
                }
                $value = intval($value);
                if($value < 0) $value = 0;

                $n = false;
                if( ($n = $this->get($key)) !== false ) {
                        $n += $value;
                        $this->set($key, $n); // exptime?
                }
                $this->unlock($key);
                return $n;
        }

        function decr($key, $value=1) {
                if ( !$this->lock($key) ) {
                        return false;
                }
                $value = intval($value);
                if($value < 0) $value = 0;

                $m = false;
                if( ($n = $this->get($key)) !== false ) {
                        $m = $n - $value;
                        if($m < 0) $m = 0;
                        $this->set($key, $m); // exptime?
                }
                $this->unlock($key);
                return $m;
        }

        function _debug($text) {
                if($this->debugmode)
                        wfDebug("BagOStuff debug: $text\n");
        }

        /**
         * Convert an optionally relative time to an absolute time
         */
        static 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();
        }

        function _expire($key) {
                $et = $this->bag[$key][1];
                if(($et == 0) || ($et > time()))
                        return false;
                $this->delete($key);
                return true;
        }

        function get($key) {
                if(!$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, BagOStuff::convertExpiry( $exptime ) );
        }

        function delete($key,$time=0) {
                if(!$this->bag[$key])
                        return false;
                unset($this->bag[$key]);
                return true;
        }

        function keys() {
                return array_keys( $this->bag );
        }
}

/**
 * Generic class to store objects in a database
 *
 * @ingroup Cache
 */
abstract class SqlBagOStuff extends BagOStuff {
        var $table;
        var $lastexpireall = 0;

        /**
         * Constructor
         *
         * @param $tablename String: name of the table to use
         */
        function __construct($tablename = 'objectcache') {
                $this->table = $tablename;
        }

        function get($key) {
                /* expire old entries if any */
                $this->garbageCollect();

                $res = $this->_query(
                        "SELECT value,exptime FROM $0 WHERE keyname='$1'", $key);
                if(!$res) {
                        $this->_debug("get: ** error: " . $this->_dberror($res) . " **");
                        return false;
                }
                if($row=$this->_fetchobject($res)) {
                        $this->_debug("get: retrieved data; exp time is " . $row->exptime);
                        if ( $row->exptime != $this->_maxdatetime() &&
                          wfTimestamp( TS_UNIX, $row->exptime ) < time() )
                        {
                                $this->_debug("get: key has expired, deleting");
                                $this->delete($key);
                                return false;
                        }
                        return $this->_unserialize($this->_blobdecode($row->value));
                } else {
                        $this->_debug('get: no matching rows');
                }
                return false;
        }

        function set($key,$value,$exptime=0) {
                if ( $this->_readonly() ) {
                        return false;
                }
                $exptime = intval($exptime);
                if($exptime < 0) $exptime = 0;
                if($exptime == 0) {
                        $exp = $this->_maxdatetime();
                } else {
                        if($exptime < 3.16e8) # ~10 years
                                $exptime += time();
                        $exp = $this->_fromunixtime($exptime);
                }
                $this->delete( $key );
                $this->_doinsert($this->getTableName(), array(
                                        'keyname' => $key,
                                        'value' => $this->_blobencode($this->_serialize($value)),
                                        'exptime' => $exp
                                ));
                return true; /* ? */
        }

        function delete($key,$time=0) {
                if ( $this->_readonly() ) {
                        return false;
                }
                $this->_query(
                        "DELETE FROM $0 WHERE keyname='$1'", $key );
                return true; /* ? */
        }

        function keys() {
                $res = $this->_query( "SELECT keyname FROM $0" );
                if(!$res) {
                        $this->_debug("keys: ** error: " . $this->_dberror($res) . " **");
                        return array();
                }
                $result = array();
                while( $row = $this->_fetchobject($res) ) {
                        $result[] = $row->keyname;
                }
                return $result;
        }

        function getTableName() {
                return $this->table;
        }

        function _query($sql) {
                $reps = func_get_args();
                $reps[0] = $this->getTableName();
                // ewwww
                for($i=0;$i<count($reps);$i++) {
                        $sql = str_replace(
                                '$' . $i,
                                $i > 0 ? $this->_strencode($reps[$i]) : $reps[$i],
                                $sql);
                }
                $res = $this->_doquery($sql);
                if($res == false) {
                        $this->_debug('query failed: ' . $this->_dberror($res));
                }
                return $res;
        }

        function _strencode($str) {
                /* Protect strings in SQL */
                return str_replace( "'", "''", $str );
        }
        function _blobencode($str) {
                return $str;
        }
        function _blobdecode($str) {
                return $str;
        }

        abstract function _doinsert($table, $vals);
        abstract function _doquery($sql);

        abstract function _readonly();

        function _freeresult($result) {
                /* stub */
                return false;
        }

        function _dberror($result) {
                /* stub */
                return 'unknown error';
        }

        abstract function _maxdatetime();
        abstract function _fromunixtime($ts);

        function garbageCollect() {
                /* Ignore 99% of requests */
                if ( !mt_rand( 0, 100 ) ) {
                        $nowtime = time();
                        /* Avoid repeating the delete within a few seconds */
                        if ( $nowtime > ($this->lastexpireall + 1) ) {
                                $this->lastexpireall = $nowtime;
                                $this->expireall();
                        }
                }
        }

        function expireall() {
                /* Remove any items that have expired */
                if ( $this->_readonly() ) {
                        return false;
                }
                $now = $this->_fromunixtime( time() );
                $this->_query( "DELETE FROM $0 WHERE exptime < '$now'" );
        }

        function deleteall() {
                /* Clear *all* items from cache table */
                if ( $this->_readonly() ) {
                        return false;
                }
                $this->_query( "DELETE FROM $0" );
        }

        /**
         * 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 $data mixed
         * @return string
         */
        function _serialize( &$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
         */
        function _unserialize( $serial ) {
                if( function_exists( 'gzinflate' ) ) {
                        $decomp = @gzinflate( $serial );
                        if( false !== $decomp ) {
                                $serial = $decomp;
                        }
                }
                $ret = unserialize( $serial );
                return $ret;
        }
}

/**
 * Stores objects in the main database of the wiki
 *
 * @ingroup Cache
 */
class MediaWikiBagOStuff extends SqlBagOStuff {
        var $tableInitialised = false;

        function _getDB(){
                static $db;
                if( !isset( $db ) )
                        $db = wfGetDB( DB_MASTER );
                return $db;
        }
        function _doquery($sql) {
                return $this->_getDB()->query( $sql, __METHOD__ );
        }
        function _doinsert($t, $v) {
                return $this->_getDB()->insert($t, $v, __METHOD__, array( 'IGNORE' ) );
        }
        function _fetchobject($result) {
                return $this->_getDB()->fetchObject($result);
        }
        function _freeresult($result) {
                return $this->_getDB()->freeResult($result);
        }
        function _dberror($result) {
                return $this->_getDB()->lastError();
        }
        function _maxdatetime() {
                if ( time() > 0x7fffffff ) {
                        return $this->_fromunixtime( 1<<62 );
                } else {
                        return $this->_fromunixtime( 0x7fffffff );
                }
        }
        function _fromunixtime($ts) {
                return $this->_getDB()->timestamp($ts);
        }
        function _readonly(){
                return wfReadOnly();
        }
        function _strencode($s) {
                return $this->_getDB()->strencode($s);
        }
        function _blobencode($s) {
                return $this->_getDB()->encodeBlob($s);
        }
        function _blobdecode($s) {
                return $this->_getDB()->decodeBlob($s);
        }
        function getTableName() {
                if ( !$this->tableInitialised ) {
                        $dbw = $this->_getDB();
                        /* This is actually a hack, we should be able
                           to use Language classes here... or not */
                        if (!$dbw)
                                throw new MWException("Could not connect to database");
                        $this->table = $dbw->tableName( $this->table );
                        $this->tableInitialised = true;
                }
                return $this->table;
        }
}

/**
 * This is a wrapper for Turck MMCache's shared memory functions.
 *
 * You can store objects with mmcache_put() and mmcache_get(), but Turck seems
 * to use a weird custom serializer that randomly segfaults. So we wrap calls
 * with serialize()/unserialize().
 *
 * The thing I noticed about the Turck serialized data was that unlike ordinary
 * serialize(), it contained the names of methods, and judging by the amount of
 * binary data, perhaps even the bytecode of the methods themselves. It may be
 * that Turck's serializer is faster, so a possible future extension would be
 * to use it for arrays but not for objects.
 *
 * @ingroup Cache
 */
class TurckBagOStuff extends BagOStuff {
        function get($key) {
                $val = mmcache_get( $key );
                if ( is_string( $val ) ) {
                        $val = unserialize( $val );
                }
                return $val;
        }

        function set($key, $value, $exptime=0) {
                mmcache_put( $key, serialize( $value ), $exptime );
                return true;
        }

        function delete($key, $time=0) {
                mmcache_rm( $key );
                return true;
        }

        function lock($key, $waitTimeout = 0 ) {
                mmcache_lock( $key );
                return true;
        }

        function unlock($key) {
                mmcache_unlock( $key );
                return true;
        }
}

/**
 * This is a wrapper for APC's shared memory functions
 *
 * @ingroup Cache
 */
class APCBagOStuff extends BagOStuff {
        function get($key) {
                $val = apc_fetch($key);
                if ( is_string( $val ) ) {
                        $val = unserialize( $val );
                }
                return $val;
        }

        function set($key, $value, $exptime=0) {
                apc_store($key, serialize($value), $exptime);
                return true;
        }

        function delete($key, $time=0) {
                apc_delete($key);
                return true;
        }
}


/**
 * This is a wrapper for eAccelerator's shared memory functions.
 *
 * This is basically identical to the Turck MMCache version,
 * mostly because eAccelerator is based on Turck MMCache.
 *
 * @ingroup Cache
 */
class eAccelBagOStuff extends BagOStuff {
        function get($key) {
                $val = eaccelerator_get( $key );
                if ( is_string( $val ) ) {
                        $val = unserialize( $val );
                }
                return $val;
        }

        function set($key, $value, $exptime=0) {
                eaccelerator_put( $key, serialize( $value ), $exptime );
                return true;
        }

        function delete($key, $time=0) {
                eaccelerator_rm( $key );
                return true;
        }

        function lock($key, $waitTimeout = 0 ) {
                eaccelerator_lock( $key );
                return true;
        }

        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;
        }

}

/**
 * @todo document
 * @ingroup Cache
 */
class DBABagOStuff extends BagOStuff {
        var $mHandler, $mFile, $mReader, $mWriter, $mDisabled;

        function __construct( $handler = 'db3', $dir = false ) {
                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 = $handler;
        }

        /**
         * Encode value and expiry for storage
         */
        function encode( $value, $expiry ) {
                # Convert to absolute time
                $expiry = BagOStuff::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;
        }
}