ObjectCache.php

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<?php
# $Id: ObjectCache.php,v 1.4 2004/06/12 03:17:39 vibber Exp $
#
# 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.,
# 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
# http://www.gnu.org/copyleft/gpl.html

# Simple generic object store
# interface is intended to be more or less compatible with
# the PHP memcached client.
#
# backends for local hash array and SQL table included:
#  $bag = new HashBagOStuff();
#  $bag = new MysqlBagOStuff($tablename); # connect to db first

class /* abstract */ BagOStuff {
        var $debugmode;
        
        function BagOStuff() {
                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;
        }
        
        /* *** 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) {
                $value = intval($value);
                if($value < 0) $value = 0;
                if( ($n = $this->get($key)) !== false ) {
                        $this->set($key, $n+$value); // exptime?
                        return $n+$value;
                } else {
                        return false;
                }
        }
        
        function decr($key, $value=1) {
                $value = intval($value);
                if($value < 0) $value = 0;
                if( ($n = $this->get($key)) !== false ) {
                        $m = $n - $value;
                        if($m < 0) $m = 0;
                        $this->set($key, $m); // exptime?
                        return $m;
                } else {
                        return false;
                }
        }
        
        function _debug($text) {
                if($this->debugmode)
                        wfDebug("BagOStuff debug: $text\n");
        }
}


/* Functional versions! */
class HashBagOStuff extends BagOStuff {
        /*
           This is a test of the interface, mainly. It stores
           things in an associative array, which is not going to
           persist between program runs.
        */
        var $bag;
        
        function HashBagOStuff() {
                $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,$exptime=0) {
                if(($exptime != 0) && ($exptime < 3600*24*30))
                        $exptime = time() + $exptime;
                $this->bag[$key] = array( $value, $exptime );
        }
        
        function delete($key,$time=0) {
                if(!$this->bag[$key])
                        return false;
                unset($this->bag[$key]);
                return true;
        }
}

/*
CREATE TABLE objectcache (
  keyname char(255) binary not null default '',
  value mediumblob,
  exptime datetime,
  unique key (keyname),
  key (exptime)
);
*/
class /* abstract */ SqlBagOStuff extends BagOStuff {
        var $table;
        function SqlBagOStuff($tablename = "objectcache") {
                $this->table = $tablename;
        }
        
        function get($key) {
                /* expire old entries if any */
                $this->expireall();
                
                $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 " . $row->exptime);
                        return unserialize($row->value);
                } else {
                        $this->_debug("get: no matching rows");
                }
                return false;
        }
        
        function set($key,$value,$exptime=0) {
                $exptime = intval($exptime);
                if($exptime < 0) $exptime = 0;
                if($exptime == 0) {
                        $exp = $this->_maxdatetime();
                } else {
                        if($exptime < 3600*24*30)
                                $exptime += time();
                        $exp = $this->_fromunixtime($exptime);
                }
                $this->delete( $key );
                $this->_query(
                        "INSERT INTO $0 (keyname,value,exptime) VALUES('$1','$2','$exp')",
                        $key, serialize($value));
                return true; /* ? */
        }
        
        function delete($key,$time=0) {
                $this->_query(
                        "DELETE FROM $0 WHERE keyname='$1'", $key );
                return true; /* ? */
        }
        
        function _query($sql) {
                $reps = func_get_args();
                $reps[0] = $this->table;
                // ewwww
                for($i=0;$i<count($reps);$i++) {
                        $sql = str_replace(
                                "$" . $i,
                                $this->_strencode($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 _doquery($sql) {
                die( "abstract function SqlBagOStuff::_doquery() must be defined" );
        }
        
        function _fetchrow($res) {
                die( "abstract function SqlBagOStuff::_fetchrow() must be defined" );
        }
        
        function _freeresult($result) {
                /* stub */
                return false;
        }
        
        function _dberror($result) {
                /* stub */
                return "unknown error";
        }
        
        function _maxdatetime() {
                die( "abstract function SqlBagOStuff::_maxdatetime() must be defined" );
        }
        
        function _fromunixtime() {
                die( "abstract function SqlBagOStuff::_fromunixtime() must be defined" );
        }
        
        function expireall() {
                /* Remove any items that have expired */
                $now=$this->_fromunixtime(time());
                $this->_query( "DELETE FROM $0 WHERE exptime<'$now'" );
        }
        
        function deleteall() {
                /* Clear *all* items from cache table */
                $this->_query( "DELETE FROM $0" );
        }
}

class MediaWikiBagOStuff extends SqlBagOStuff {
        function _doquery($sql) {
                return wfQuery($sql, DB_READ, "MediaWikiBagOStuff:_doquery");
        }
        function _fetchobject($result) {
                return wfFetchObject($result);
        }
        function _freeresult($result) {
                return wfFreeResult($result);
        }
        function _dberror($result) {
                return wfLastError();
        }
        function _maxdatetime() {
                return "9999-12-31 12:59:59";
        }
        function _fromunixtime($ts) {
                return gmdate( "Y-m-d H:i:s", $ts );
        }
        function _strencode($s) {
                return wfStrEncode($s);
        }
}

?>

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