includes/historyblob/ConcatenatedGzipHistoryBlob.php

   1 <?php
   2 /**
   3  * Efficient concatenated text storage.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * Concatenated gzip (CGZ) storage
  25  * Improves compression ratio by concatenating like objects before gzipping
  26  */
  27 class ConcatenatedGzipHistoryBlob implements HistoryBlob {
  28         public $mVersion = 0, $mCompressed = false, $mItems = [], $mDefaultHash = '';
  29         public $mSize = 0;
  30         public $mMaxSize = 10000000;
  31         public $mMaxCount = 100;
  32
  33         public function __construct() {
  34                 if ( !function_exists( 'gzdeflate' ) ) {
  35                         throw new MWException( "Need zlib support to read or write this "
  36                                 . "kind of history object (ConcatenatedGzipHistoryBlob)\n" );
  37                 }
  38         }
  39
  40         /**
  41          * @param string $text
  42          * @return string
  43          */
  44         public function addItem( $text ) {
  45                 $this->uncompress();
  46                 $hash = md5( $text );
  47                 if ( !isset( $this->mItems[$hash] ) ) {
  48                         $this->mItems[$hash] = $text;
  49                         $this->mSize += strlen( $text );
  50                 }
  51                 return $hash;
  52         }
  53
  54         /**
  55          * @param string $hash
  56          * @return array|bool
  57          */
  58         public function getItem( $hash ) {
  59                 $this->uncompress();
  60                 if ( array_key_exists( $hash, $this->mItems ) ) {
  61                         return $this->mItems[$hash];
  62                 } else {
  63                         return false;
  64                 }
  65         }
  66
  67         /**
  68          * @param string $text
  69          * @return void
  70          */
  71         public function setText( $text ) {
  72                 $this->uncompress();
  73                 $this->mDefaultHash = $this->addItem( $text );
  74         }
  75
  76         /**
  77          * @return array|bool
  78          */
  79         public function getText() {
  80                 $this->uncompress();
  81                 return $this->getItem( $this->mDefaultHash );
  82         }
  83
  84         /**
  85          * Remove an item
  86          *
  87          * @param string $hash
  88          */
  89         public function removeItem( $hash ) {
  90                 $this->mSize -= strlen( $this->mItems[$hash] );
  91                 unset( $this->mItems[$hash] );
  92         }
  93
  94         /**
  95          * Compress the bulk data in the object
  96          */
  97         public function compress() {
  98                 if ( !$this->mCompressed ) {
  99                         $this->mItems = gzdeflate( serialize( $this->mItems ) );
 100                         $this->mCompressed = true;
 101                 }
 102         }
 103
 104         /**
 105          * Uncompress bulk data
 106          */
 107         public function uncompress() {
 108                 if ( $this->mCompressed ) {
 109                         $this->mItems = unserialize( gzinflate( $this->mItems ) );
 110                         $this->mCompressed = false;
 111                 }
 112         }
 113
 114         /**
 115          * @return array
 116          */
 117         function __sleep() {
 118                 $this->compress();
 119                 return [ 'mVersion', 'mCompressed', 'mItems', 'mDefaultHash' ];
 120         }
 121
 122         function __wakeup() {
 123                 $this->uncompress();
 124         }
 125
 126         /**
 127          * Helper function for compression jobs
 128          * Returns true until the object is "full" and ready to be committed
 129          *
 130          * @return bool
 131          */
 132         public function isHappy() {
 133                 return $this->mSize < $this->mMaxSize
 134                         && count( $this->mItems ) < $this->mMaxCount;
 135         }
 136 }
 137
 138 // phpcs:ignore Generic.CodeAnalysis.UnconditionalIfStatement.Found
 139 if ( false ) {
 140         // Blobs generated by MediaWiki < 1.5 on PHP 4 were serialized with the
 141         // class name coerced to lowercase. We can improve efficiency by adding
 142         // autoload entries for the lowercase variants of these classes (T166759).
 143         // The code below is never executed, but it is picked up by the AutoloadGenerator
 144         // parser, which scans for class_alias() calls.
 145         // @phan-suppress-next-line PhanRedefineClassAlias
 146         class_alias( ConcatenatedGzipHistoryBlob::class, 'concatenatedgziphistoryblob' );
 147 }