includes/HistoryBlob.php

   1 <?php
   2 /**
   3  *
   4  * @package MediaWiki
   5  */
   6
   7 /**
   8  * Pure virtual parent
   9  * @package MediaWiki
  10  */
  11 class HistoryBlob
  12 {
  13         # setMeta and getMeta currently aren't used for anything, I just thought they might be useful in the future
  14         # The meta value is a single string
  15         function setMeta( $meta ) {}
  16
  17         # Gets the meta-value
  18         function getMeta() {}
  19
  20         # Adds an item of text, returns a stub object which points to the item
  21         # You must call setLocation() on the stub object before storing it to the database
  22         function addItem() {}
  23
  24         # Get item by hash
  25         function getItem( $hash ) {}
  26
  27         # Set the "default text"
  28         # This concept is an odd property of the current DB schema, whereby each text item has a revision
  29         # associated with it. The default text is the text of the associated revision. There may, however,
  30         # be other revisions in the same object
  31         function setText() {}
  32
  33         # Get default text. This is called from Article::getRevisionText()
  34         function getText() {}
  35 }
  36
  37 /**
  38  * The real object
  39  * @package MediaWiki
  40  */
  41 class ConcatenatedGzipHistoryBlob extends HistoryBlob
  42 {
  43         /* private */ var $mVersion = 0, $mCompressed = false, $mItems = array(), $mDefaultHash = '';
  44         /* private */ var $mFast = 0, $mSize = 0;
  45
  46         function ConcatenatedGzipHistoryBlob() {
  47                 if ( !function_exists( 'gzdeflate' ) ) {
  48                         die( "Need zlib support to read or write this kind of history object (ConcatenatedGzipHistoryBlob)\n" );
  49                 }
  50         }
  51
  52         function setMeta( $metaData ) {
  53                 $this->uncompress();
  54                 $this->mItems['meta'] = $metaData;
  55         }
  56
  57         function getMeta() {
  58                 $this->uncompress();
  59                 return $this->mItems['meta'];
  60         }
  61
  62         function addItem( $text ) {
  63                 $this->uncompress();
  64                 $hash = md5( $text );
  65                 $this->mItems[$hash] = $text;
  66                 $this->mSize += strlen( $text );
  67
  68                 $stub = new HistoryBlobStub( $hash );
  69                 return $stub;
  70         }
  71
  72         function getItem( $hash ) {
  73                 $this->uncompress();
  74                 if ( array_key_exists( $hash, $this->mItems ) ) {
  75                         return $this->mItems[$hash];
  76                 } else {
  77                         return false;
  78                 }
  79         }
  80
  81         function removeItem( $hash ) {
  82                 $this->mSize -= strlen( $this->mItems[$hash] );
  83                 unset( $this->mItems[$hash] );
  84         }
  85
  86         function compress() {
  87                 if ( !$this->mCompressed  ) {
  88                         $this->mItems = gzdeflate( serialize( $this->mItems ) );
  89                         $this->mCompressed = true;
  90                 }
  91         }
  92
  93         function uncompress() {
  94                 if ( $this->mCompressed ) {
  95                         $this->mItems = unserialize( gzinflate( $this->mItems ) );
  96                         $this->mCompressed = false;
  97                 }
  98         }
  99
 100         function getText() {
 101                 $this->uncompress();
 102                 return $this->getItem( $this->mDefaultHash );
 103         }
 104
 105         function setText( $text ) {
 106                 $this->uncompress();
 107                 $stub = $this->addItem( $text );
 108                 $this->mDefaultHash = $stub->mHash;
 109         }
 110
 111         function __sleep() {
 112                 $this->compress();
 113                 return array( 'mVersion', 'mCompressed', 'mItems', 'mDefaultHash' );
 114         }
 115
 116         function __wakeup() {
 117                 $this->uncompress();
 118         }
 119
 120         # Determines if this object is happy
 121         function isHappy( $maxFactor, $factorThreshold ) {
 122                 if ( count( $this->mItems ) == 0 ) {
 123                         return true;
 124                 }
 125                 if ( $this->mFast ) {
 126                         $this->uncompress();
 127                         $record = serialize( $this->mItems );
 128                         $size = strlen( $record );
 129                         $avgUncompressed = $size / count( $this->mItems );
 130                         $compressed = strlen( gzdeflate( $record ) );
 131
 132                         if ( $compressed < $factorThreshold * 1024 ) {
 133                                 return true;
 134                         } else {
 135                                 return $avgUncompressed * $maxFactor < $compressed;
 136                         }
 137                 } else {
 138                         return count( $this->mItems ) <= 10;
 139                 }
 140         }
 141 }
 142
 143 class HistoryBlobStub
 144 {
 145         var $mOldId, $mHash;
 146
 147         function HistoryBlobStub( $hash = '', $oldid = 0 ) {
 148                 $this->mHash = $hash;
 149         }
 150
 151         # Sets the location (old_id) of the main object to which this object points
 152         function setLocation( $id ) {
 153                 $this->mOldId = $id;
 154         }
 155
 156         function getText() {
 157                 $dbr =& wfGetDB( DB_SLAVE );
 158                 $row = $dbr->selectRow( 'old', array( 'old_flags', 'old_text' ), array( 'old_id' => $this->mOldId ) );
 159                 if ( !$row || $row->old_flags != 'object' ) {
 160                         return false;
 161                 }
 162                 $obj = unserialize( $row->old_text );
 163                 if ( !is_object( $obj ) ) {
 164                         $obj = unserialize( $obj );
 165                 }
 166                 return $obj->getItem( $this->mHash );
 167         }
 168
 169         function getHash() {
 170                 return $this->mHash;
 171         }
 172 }
 173 ?>