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