includes/cache/FileCacheBase.php

   1 <?php
   2 /**
   3  * Data storage in the file system.
   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  * @ingroup Cache
  22  */
  23
  24 /**
  25  * Base class for data storage in the file system.
  26  *
  27  * @ingroup Cache
  28  */
  29 abstract class FileCacheBase {
  30         protected $mKey;
  31         protected $mType = 'object';
  32         protected $mExt = 'cache';
  33         protected $mFilePath;
  34         protected $mUseGzip;
  35         /* lazy loaded */
  36         protected $mCached;
  37
  38         /* @todo configurable? */
  39         const MISS_FACTOR = 15; // log 1 every MISS_FACTOR cache misses
  40         const MISS_TTL_SEC = 3600; // how many seconds ago is "recent"
  41
  42         protected function __construct() {
  43                 global $wgUseGzip;
  44
  45                 $this->mUseGzip = (bool)$wgUseGzip;
  46         }
  47
  48         /**
  49          * Get the base file cache directory
  50          * @return string
  51          */
  52         final protected function baseCacheDirectory() {
  53                 global $wgFileCacheDirectory;
  54
  55                 return $wgFileCacheDirectory;
  56         }
  57
  58         /**
  59          * Get the base cache directory (not specific to this file)
  60          * @return string
  61          */
  62         abstract protected function cacheDirectory();
  63
  64         /**
  65          * Get the path to the cache file
  66          * @return string
  67          */
  68         protected function cachePath() {
  69                 if ( $this->mFilePath !== null ) {
  70                         return $this->mFilePath;
  71                 }
  72
  73                 $dir = $this->cacheDirectory();
  74                 # Build directories (methods include the trailing "/")
  75                 $subDirs = $this->typeSubdirectory() . $this->hashSubdirectory();
  76                 # Avoid extension confusion
  77                 $key = str_replace( '.', '%2E', urlencode( $this->mKey ) );
  78                 # Build the full file path
  79                 $this->mFilePath = "{$dir}/{$subDirs}{$key}.{$this->mExt}";
  80                 if ( $this->useGzip() ) {
  81                         $this->mFilePath .= '.gz';
  82                 }
  83
  84                 return $this->mFilePath;
  85         }
  86
  87         /**
  88          * Check if the cache file exists
  89          * @return bool
  90          */
  91         public function isCached() {
  92                 if ( $this->mCached === null ) {
  93                         $this->mCached = file_exists( $this->cachePath() );
  94                 }
  95
  96                 return $this->mCached;
  97         }
  98
  99         /**
 100          * Get the last-modified timestamp of the cache file
 101          * @return string|bool TS_MW timestamp
 102          */
 103         public function cacheTimestamp() {
 104                 $timestamp = filemtime( $this->cachePath() );
 105
 106                 return ( $timestamp !== false )
 107                         ? wfTimestamp( TS_MW, $timestamp )
 108                         : false;
 109         }
 110
 111         /**
 112          * Check if up to date cache file exists
 113          * @param string $timestamp MW_TS timestamp
 114          *
 115          * @return bool
 116          */
 117         public function isCacheGood( $timestamp = '' ) {
 118                 global $wgCacheEpoch;
 119
 120                 if ( !$this->isCached() ) {
 121                         return false;
 122                 }
 123
 124                 $cachetime = $this->cacheTimestamp();
 125                 $good = ( $timestamp <= $cachetime && $wgCacheEpoch <= $cachetime );
 126                 wfDebug( __METHOD__ .
 127                         ": cachetime $cachetime, touched '{$timestamp}' epoch {$wgCacheEpoch}, good $good\n" );
 128
 129                 return $good;
 130         }
 131
 132         /**
 133          * Check if the cache is gzipped
 134          * @return bool
 135          */
 136         protected function useGzip() {
 137                 return $this->mUseGzip;
 138         }
 139
 140         /**
 141          * Get the uncompressed text from the cache
 142          * @return string
 143          */
 144         public function fetchText() {
 145                 if ( $this->useGzip() ) {
 146                         $fh = gzopen( $this->cachePath(), 'rb' );
 147
 148                         return stream_get_contents( $fh );
 149                 } else {
 150                         return file_get_contents( $this->cachePath() );
 151                 }
 152         }
 153
 154         /**
 155          * Save and compress text to the cache
 156          * @param string $text
 157          * @return string Compressed text
 158          */
 159         public function saveText( $text ) {
 160                 if ( $this->useGzip() ) {
 161                         $text = gzencode( $text );
 162                 }
 163
 164                 $this->checkCacheDirs(); // build parent dir
 165                 if ( !file_put_contents( $this->cachePath(), $text, LOCK_EX ) ) {
 166                         wfDebug( __METHOD__ . "() failed saving " . $this->cachePath() . "\n" );
 167                         $this->mCached = null;
 168
 169                         return false;
 170                 }
 171
 172                 $this->mCached = true;
 173
 174                 return $text;
 175         }
 176
 177         /**
 178          * Clear the cache for this page
 179          * @return void
 180          */
 181         public function clearCache() {
 182                 MediaWiki\suppressWarnings();
 183                 unlink( $this->cachePath() );
 184                 MediaWiki\restoreWarnings();
 185                 $this->mCached = false;
 186         }
 187
 188         /**
 189          * Create parent directors of $this->cachePath()
 190          * @return void
 191          */
 192         protected function checkCacheDirs() {
 193                 wfMkdirParents( dirname( $this->cachePath() ), null, __METHOD__ );
 194         }
 195
 196         /**
 197          * Get the cache type subdirectory (with trailing slash)
 198          * An extending class could use that method to alter the type -> directory
 199          * mapping. @see HTMLFileCache::typeSubdirectory() for an example.
 200          *
 201          * @return string
 202          */
 203         protected function typeSubdirectory() {
 204                 return $this->mType . '/';
 205         }
 206
 207         /**
 208          * Return relative multi-level hash subdirectory (with trailing slash)
 209          * or the empty string if not $wgFileCacheDepth
 210          * @return string
 211          */
 212         protected function hashSubdirectory() {
 213                 global $wgFileCacheDepth;
 214
 215                 $subdir = '';
 216                 if ( $wgFileCacheDepth > 0 ) {
 217                         $hash = md5( $this->mKey );
 218                         for ( $i = 1; $i <= $wgFileCacheDepth; $i++ ) {
 219                                 $subdir .= substr( $hash, 0, $i ) . '/';
 220                         }
 221                 }
 222
 223                 return $subdir;
 224         }
 225
 226         /**
 227          * Roughly increments the cache misses in the last hour by unique visitors
 228          * @param WebRequest $request
 229          * @return void
 230          */
 231         public function incrMissesRecent( WebRequest $request ) {
 232                 if ( mt_rand( 0, self::MISS_FACTOR - 1 ) == 0 ) {
 233                         $cache = ObjectCache::getLocalClusterInstance();
 234                         # Get a large IP range that should include the user  even if that
 235                         # person's IP address changes
 236                         $ip = $request->getIP();
 237                         if ( !IP::isValid( $ip ) ) {
 238                                 return;
 239                         }
 240                         $ip = IP::isIPv6( $ip )
 241                                 ? IP::sanitizeRange( "$ip/32" )
 242                                 : IP::sanitizeRange( "$ip/16" );
 243
 244                         # Bail out if a request already came from this range...
 245                         $key = wfMemcKey( get_class( $this ), 'attempt', $this->mType, $this->mKey, $ip );
 246                         if ( $cache->get( $key ) ) {
 247                                 return; // possibly the same user
 248                         }
 249                         $cache->set( $key, 1, self::MISS_TTL_SEC );
 250
 251                         # Increment the number of cache misses...
 252                         $key = $this->cacheMissKey();
 253                         if ( $cache->get( $key ) === false ) {
 254                                 $cache->set( $key, 1, self::MISS_TTL_SEC );
 255                         } else {
 256                                 $cache->incr( $key );
 257                         }
 258                 }
 259         }
 260
 261         /**
 262          * Roughly gets the cache misses in the last hour by unique visitors
 263          * @return int
 264          */
 265         public function getMissesRecent() {
 266                 $cache = ObjectCache::getLocalClusterInstance();
 267
 268                 return self::MISS_FACTOR * $cache->get( $this->cacheMissKey() );
 269         }
 270
 271         /**
 272          * @return string
 273          */
 274         protected function cacheMissKey() {
 275                 return wfMemcKey( get_class( $this ), 'misses', $this->mType, $this->mKey );
 276         }
 277 }