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<?php
/**
* Efficient concatenated text storage.
*
* 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
*/
/**
* Concatenated gzip (CGZ) storage
* Improves compression ratio by concatenating like objects before gzipping
*
* WARNING: Objects of this class are serialized and permanently stored in the DB.
* Do not change the name or visibility of any property!
*/
class ConcatenatedGzipHistoryBlob implements HistoryBlob {
/** @var int */
public $mVersion = 0;
/** @var bool */
public $mCompressed = false;
/** @var string[]|string Array if uncompressed, string if compressed */
public $mItems = [];
/** @var string */
public $mDefaultHash = '';
/** @var int */
public $mSize = 0;
/** @var int */
public $mMaxSize = 10_000_000;
/** @var int */
public $mMaxCount = 100;
public function __construct() {
if ( !function_exists( 'gzdeflate' ) ) {
throw new RuntimeException( "Need zlib support to read or write this "
. "kind of history object (ConcatenatedGzipHistoryBlob)\n" );
}
}
/**
* @param string $text
* @return string
*/
public function addItem( $text ) {
$this->uncompress();
$hash = md5( $text );
if ( !isset( $this->mItems[$hash] ) ) {
$this->mItems[$hash] = $text;
$this->mSize += strlen( $text );
}
return $hash;
}
/**
* @param string $hash
* @return string|false
*/
public function getItem( $hash ) {
$this->uncompress();
if ( array_key_exists( $hash, $this->mItems ) ) {
return $this->mItems[$hash];
} else {
return false;
}
}
/**
* @param string $text
* @return void
*/
public function setText( $text ) {
$this->uncompress();
$this->mDefaultHash = $this->addItem( $text );
}
/**
* @return string|false
*/
public function getText() {
$this->uncompress();
return $this->getItem( $this->mDefaultHash );
}
/**
* Remove an item
*
* @param string $hash
*/
public function removeItem( $hash ) {
$this->mSize -= strlen( $this->mItems[$hash] );
unset( $this->mItems[$hash] );
}
/**
* Compress the bulk data in the object
*/
public function compress() {
if ( !$this->mCompressed ) {
$this->mItems = gzdeflate( serialize( $this->mItems ) );
$this->mCompressed = true;
}
}
/**
* Uncompress bulk data
*/
public function uncompress() {
if ( $this->mCompressed ) {
$this->mItems = HistoryBlobUtils::unserializeArray( gzinflate( $this->mItems ) );
$this->mCompressed = false;
}
}
/**
* @return array
*/
public function __sleep() {
$this->compress();
return [ 'mVersion', 'mCompressed', 'mItems', 'mDefaultHash' ];
}
public function __wakeup() {
$this->uncompress();
}
/**
* Helper function for compression jobs
* Returns true until the object is "full" and ready to be committed
*
* @return bool
*/
public function isHappy() {
return $this->mSize < $this->mMaxSize
&& count( $this->mItems ) < $this->mMaxCount;
}
}
// Blobs generated by MediaWiki < 1.5 on PHP 4 were serialized with the
// class name coerced to lowercase. We can improve efficiency by adding
// autoload entries for the lowercase variants of these classes (T166759).
// The code below is never executed, but it is picked up by the AutoloadGenerator
// parser, which scans for class_alias() calls.
/*
class_alias( ConcatenatedGzipHistoryBlob::class, 'concatenatedgziphistoryblob' );
*/
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