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         /* lazy loaded */
  14         protected $mCached;
  15
  16         /* @TODO: configurable? */
  17         const MISS_FACTOR = 15; // log 1 every MISS_FACTOR cache misses
  18         const MISS_TTL_SEC = 3600; // how many seconds ago is "recent"
  19
  20         protected function __construct() {
  21                 global $wgUseGzip;
  22
  23                 $this->mUseGzip = (bool)$wgUseGzip;
  24         }
  25
  26         /**
  27          * Get the base file cache directory
  28          * @return string
  29          */
  30         final protected function baseCacheDirectory() {
  31                 global $wgCacheDirectory, $wgFileCacheDirectory, $wgFileCacheDepth;
  32                 if ( $wgFileCacheDirectory ) {
  33                         $dir = $wgFileCacheDirectory;
  34                 } elseif ( $wgCacheDirectory ) {
  35                         $dir = $wgCacheDirectory;
  36                 } else {
  37                         throw new MWException( 'Please set $wgCacheDirectory in LocalSettings.php if you wish to use the HTML file cache' );
  38                 }
  39                 return $dir;
  40         }
  41
  42         /**
  43          * Get the base cache directory (not speficic to this file)
  44          * @return string
  45          */
  46         abstract protected function cacheDirectory();
  47
  48         /**
  49          * Get the path to the cache file
  50          * @return string
  51          */
  52         protected function cachePath() {
  53                 if ( $this->mFilePath !== null ) {
  54                         return $this->mFilePath;
  55                 }
  56
  57                 $dir = $this->cacheDirectory();
  58                 # Build directories (methods include the trailing "/")
  59                 $subDirs = $this->typeSubdirectory() . $this->hashSubdirectory();
  60                 # Avoid extension confusion
  61                 $key = str_replace( '.', '%2E', urlencode( $this->mKey ) );
  62                 # Build the full file path
  63                 $this->mFilePath = "{$dir}/{$subDirs}{$key}.{$this->mExt}";
  64                 if ( $this->useGzip() ) {
  65                         $this->mFilePath .= '.gz';
  66                 }
  67
  68                 return $this->mFilePath;
  69         }
  70
  71         /**
  72          * Check if the cache file exists
  73          * @return bool
  74          */
  75         public function isCached() {
  76                 if ( $this->mCached === null ) {
  77                         $this->mCached = file_exists( $this->cachePath() );
  78                 }
  79                 return $this->mCached;
  80         }
  81
  82         /**
  83          * Get the last-modified timestamp of the cache file
  84          * @return string|false TS_MW timestamp
  85          */
  86         public function cacheTimestamp() {
  87                 $timestamp = filemtime( $this->cachePath() );
  88                 return ( $timestamp !== false )
  89                         ? wfTimestamp( TS_MW, $timestamp )
  90                         : false;
  91         }
  92
  93         /**
  94          * Check if up to date cache file exists
  95          * @param $timestamp string MW_TS timestamp
  96          *
  97          * @return bool
  98          */
  99         public function isCacheGood( $timestamp = '' ) {
 100                 global $wgCacheEpoch;
 101
 102                 if ( !$this->isCached() ) {
 103                         return false;
 104                 }
 105
 106                 $cachetime = $this->cacheTimestamp();
 107                 $good = ( $timestamp <= $cachetime && $wgCacheEpoch <= $cachetime );
 108                 wfDebug( __METHOD__ . ": cachetime $cachetime, touched '{$timestamp}' epoch {$wgCacheEpoch}, good $good\n");
 109
 110                 return $good;
 111         }
 112
 113         /**
 114          * Check if the cache is gzipped
 115          * @return bool
 116          */
 117         protected function useGzip() {
 118                 return $this->mUseGzip;
 119         }
 120
 121         /**
 122          * Get the uncompressed text from the cache
 123          * @return string
 124          */
 125         public function fetchText() {
 126                 if ( $this->useGzip() ) {
 127                         /* Why is there no gzfile_get_contents() or gzdecode()? */
 128                         return implode( '', gzfile( $this->cachePath() ) );
 129                 } else {
 130                         return file_get_contents( $this->cachePath() );
 131                 }
 132         }
 133
 134         /**
 135          * Save and compress text to the cache
 136          * @return string compressed text
 137          */
 138         public function saveText( $text ) {
 139                 global $wgUseFileCache;
 140
 141                 if ( !$wgUseFileCache ) {
 142                         return false;
 143                 }
 144
 145                 if ( $this->useGzip() ) {
 146                         $text = gzencode( $text );
 147                 }
 148
 149                 $this->checkCacheDirs(); // build parent dir
 150                 if ( !file_put_contents( $this->cachePath(), $text, LOCK_EX ) ) {
 151                         $this->mCached = null;
 152                         return false;
 153                 }
 154
 155                 $this->mCached = true;
 156                 return $text;
 157         }
 158
 159         /**
 160          * Clear the cache for this page
 161          * @return void
 162          */
 163         public function clearCache() {
 164                 wfSuppressWarnings();
 165                 unlink( $this->cachePath() );
 166                 wfRestoreWarnings();
 167                 $this->mCached = false;
 168         }
 169
 170         /**
 171          * Create parent directors of $this->cachePath()
 172          * @return void
 173          */
 174         protected function checkCacheDirs() {
 175                 wfMkdirParents( dirname( $this->cachePath() ), null, __METHOD__ );
 176         }
 177
 178         /**
 179          * Get the cache type subdirectory (with trailing slash) or the empty string
 180          * @return string
 181          */
 182         protected function typeSubdirectory() {
 183                 return $this->mType . '/';
 184         }
 185
 186         /**
 187          * Return relative multi-level hash subdirectory (with trailing slash)
 188          * or the empty string if not $wgFileCacheDepth
 189          * @return string
 190          */
 191         protected function hashSubdirectory() {
 192                 global $wgFileCacheDepth;
 193
 194                 $subdir = '';
 195                 if ( $wgFileCacheDepth > 0 ) {
 196                         $hash = md5( $this->mKey );
 197                         for ( $i = 1; $i <= $wgFileCacheDepth; $i++ ) {
 198                                 $subdir .= substr( $hash, 0, $i ) . '/';
 199                         }
 200                 }
 201
 202                 return $subdir;
 203         }
 204
 205         /**
 206          * Roughly increments the cache misses in the last hour by unique visitors
 207          * @param $request WebRequest
 208          * @return void
 209          */
 210         public function incrMissesRecent( WebRequest $request ) {
 211                 global $wgMemc;
 212                 if ( mt_rand( 0, self::MISS_FACTOR - 1 ) == 0 ) {
 213                         # Get an large IP range that should include the user
 214                         # even if that person's IP address changes...
 215                         $ip = $request->getIP();
 216                         if ( !IP::isValid( $ip ) ) {
 217                                 return;
 218                         }
 219                         $ip = IP::isIPv6( $ip )
 220                                 ? IP::sanitizeRange( "$ip/64" )
 221                                 : IP::sanitizeRange( "$ip/16" );
 222
 223                         # Bail out if a request already came from this range...
 224                         $key = wfMemcKey( get_class( $this ), 'attempt', $this->mType, $this->mKey, $ip );
 225                         if ( $wgMemc->get( $key ) ) {
 226                                 return; // possibly the same user
 227                         }
 228                         $wgMemc->set( $key, 1, self::MISS_TTL_SEC );
 229
 230                         # Increment the number of cache misses...
 231                         $key = $this->cacheMissKey();
 232                         if ( $wgMemc->get( $key ) === false ) {
 233                                 $wgMemc->set( $key, 1, self::MISS_TTL_SEC );
 234                         } else {
 235                                 $wgMemc->incr( $key );
 236                         }
 237                 }
 238         }
 239
 240         /**
 241          * Roughly gets the cache misses in the last hour by unique visitors
 242          * @return int
 243          */
 244         public function getMissesRecent() {
 245                 global $wgMemc;
 246                 return self::MISS_FACTOR * $wgMemc->get( $this->cacheMissKey() );
 247         }
 248
 249         /**
 250          * @return string
 251          */
 252         protected function cacheMissKey() {
 253                 return wfMemcKey( get_class( $this ), 'misses', $this->mType, $this->mKey );
 254         }
 255 }