includes/cache/FileCacheBase.php

   1 <?php
   2 /**
   3  * Contain the FileCacheBase class
   4  * @file
   5  * @ingroup Cache
   6  */
   7 abstract class FileCacheBase {
   8         protected $mKey;
   9         protected $mType = 'object';
  10         protected $mExt = 'cache';
  11         protected $mFilePath;
  12         protected $mUseGzip;
  13
  14         /* @TODO: configurable? */
  15         const MISS_FACTOR = 10; // log 1 every MISS_FACTOR cache misses
  16
  17         protected function __construct() {
  18                 global $wgUseGzip;
  19
  20                 $this->mUseGzip = (bool)$wgUseGzip;
  21         }
  22
  23         /**
  24          * Get the base file cache directory
  25          * @return string
  26          */
  27         final protected function baseCacheDirectory() {
  28                 global $wgCacheDirectory, $wgFileCacheDirectory, $wgFileCacheDepth;
  29                 if ( $wgFileCacheDirectory ) {
  30                         $dir = $wgFileCacheDirectory;
  31                 } elseif ( $wgCacheDirectory ) {
  32                         $dir = $wgCacheDirectory;
  33                 } else {
  34                         throw new MWException( 'Please set $wgCacheDirectory in LocalSettings.php if you wish to use the HTML file cache' );
  35                 }
  36                 return $dir;
  37         }
  38
  39         /**
  40          * Get the base cache directory (not speficic to this file)
  41          * @return string
  42          */
  43         abstract protected function cacheDirectory();
  44
  45         /**
  46          * Get the path to the cache file
  47          * @return string
  48          */
  49         protected function cachePath() {
  50                 if ( $this->mFilePath !== null ) {
  51                         return $this->mFilePath;
  52                 }
  53
  54                 $dir = $this->cacheDirectory();
  55                 # Build directories (methods include the trailing "/")
  56                 $subDirs = $this->typeSubdirectory() . $this->hashSubdirectory();
  57                 # Avoid extension confusion
  58                 $key = str_replace( '.', '%2E', urlencode( $this->mKey ) );
  59                 # Build the full file path
  60                 $this->mFilePath = "{$dir}/{$subDirs}{$key}.{$this->mExt}";
  61                 if ( $this->useGzip() ) {
  62                         $this->mFilePath .= '.gz';
  63                 }
  64
  65                 return $this->mFilePath;
  66         }
  67
  68         /**
  69          * Check if the cache file exists
  70          * @return bool
  71          */
  72         public function isCached() {
  73                 return file_exists( $this->cachePath() );
  74         }
  75
  76         /**
  77          * Get the last-modified timestamp of the cache file
  78          * @return string|false TS_MW timestamp
  79          */
  80         public function cacheTimestamp() {
  81                 $timestamp = filemtime( $this->cachePath() );
  82                 return ( $timestamp !== false )
  83                         ? wfTimestamp( TS_MW, $timestamp )
  84                         : false;
  85         }
  86
  87         /**
  88          * Check if up to date cache file exists
  89          * @param $timestamp string MW_TS timestamp
  90          *
  91          * @return bool
  92          */
  93         public function isCacheGood( $timestamp = '' ) {
  94                 global $wgCacheEpoch;
  95
  96                 if ( !$this->isCached() ) {
  97                         return false;
  98                 }
  99
 100                 $cachetime = $this->cacheTimestamp();
 101                 $good = ( $timestamp <= $cachetime && $wgCacheEpoch <= $cachetime );
 102                 wfDebug( __METHOD__ . ": cachetime $cachetime, touched '{$timestamp}' epoch {$wgCacheEpoch}, good $good\n");
 103
 104                 return $good;
 105         }
 106
 107         /**
 108          * Check if the cache is gzipped
 109          * @return bool
 110          */
 111         protected function useGzip() {
 112                 return $this->mUseGzip;
 113         }
 114
 115         /**
 116          * Get the uncompressed text from the cache
 117          * @return string
 118          */
 119         public function fetchText() {
 120                 if ( $this->useGzip() ) {
 121                         /* Why is there no gzfile_get_contents() or gzdecode()? */
 122                         return implode( '', gzfile( $this->cachePath() ) );
 123                 } else {
 124                         return file_get_contents( $this->cachePath() );
 125                 }
 126         }
 127
 128         /**
 129          * Save and compress text to the cache
 130          * @return string compressed text
 131          */
 132         public function saveText( $text ) {
 133                 global $wgUseFileCache;
 134
 135                 if ( !$wgUseFileCache ) {
 136                         return false;
 137                 }
 138
 139                 if ( $this->useGzip() ) {
 140                         $text = gzencode( $text );
 141                 }
 142
 143                 $this->checkCacheDirs(); // build parent dir
 144                 if ( !file_put_contents( $this->cachePath(), $text, LOCK_EX ) ) {
 145                         return false;
 146                 }
 147
 148                 return $text;
 149         }
 150
 151         /**
 152          * Clear the cache for this page
 153          * @return void
 154          */
 155         public function clearCache() {
 156                 wfSuppressWarnings();
 157                 unlink( $this->cachePath() );
 158                 wfRestoreWarnings();
 159         }
 160
 161         /**
 162          * Create parent directors of $this->cachePath()
 163          * @return void
 164          */
 165         protected function checkCacheDirs() {
 166                 wfMkdirParents( dirname( $this->cachePath() ), null, __METHOD__ );
 167         }
 168
 169         /**
 170          * Get the cache type subdirectory (with trailing slash) or the empty string
 171          * @return string
 172          */
 173         protected function typeSubdirectory() {
 174                 return $this->mType . '/';
 175         }
 176
 177         /**
 178          * Return relative multi-level hash subdirectory (with trailing slash)
 179          * or the empty string if not $wgFileCacheDepth
 180          * @return string
 181          */
 182         protected function hashSubdirectory() {
 183                 global $wgFileCacheDepth;
 184
 185                 $subdir = '';
 186                 if ( $wgFileCacheDepth > 0 ) {
 187                         $hash = md5( $this->mKey );
 188                         for ( $i = 1; $i <= $wgFileCacheDepth; $i++ ) {
 189                                 $subdir .= substr( $hash, 0, $i ) . '/';
 190                         }
 191                 }
 192
 193                 return $subdir;
 194         }
 195
 196         /**
 197          * Roughly increments the cache misses in the last hour by unique visitors
 198          * @param $request WebRequest
 199          * @return void
 200          */
 201         public function incrMissesRecent( WebRequest $request ) {
 202                 global $wgMemc;
 203                 if ( mt_rand( 0, self::MISS_FACTOR - 1 ) == 0 ) {
 204                         # Get an large IP range that should include the user
 205                         # even if that person's IP address changes...
 206                         $ip = $request->getIP();
 207                         if ( !IP::isValid( $ip ) ) {
 208                                 return;
 209                         }
 210                         $ip = IP::isIPv6( $ip )
 211                                 ? IP::sanitizeRange( "$ip/64" )
 212                                 : IP::sanitizeRange( "$ip/16" );
 213
 214                         # Bail out if a request already came from this range...
 215                         $key = wfMemcKey( get_class( $this ), 'attempt', $this->mType, $this->mKey, $ip );
 216                         if ( $wgMemc->get( $key ) ) {
 217                                 return; // possibly the same user
 218                         }
 219                         $wgMemc->set( $key, 1, 3600 );
 220
 221                         # Increment the number of cache misses...
 222                         $key = $this->cacheMissKey();
 223                         if ( $wgMemc->get( $key ) === false ) {
 224                                 $wgMemc->set( $key, 1, 3600 );
 225                         } else {
 226                                 $wgMemc->incr( $key );
 227                         }
 228                 }
 229         }
 230
 231         /**
 232          * Roughly gets the cache misses in the last hour by unique visitors
 233          * @return int
 234          */
 235         public function getMissesRecent() {
 236                 global $wgMemc;
 237                 return self::MISS_FACTOR * $wgMemc->get( $this->cacheMissKey() );
 238         }
 239
 240         /**
 241          * @return string
 242          */
 243         protected function cacheMissKey() {
 244                 return wfMemcKey( get_class( $this ), 'misses', $this->mType, $this->mKey );
 245         }
 246 }