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 $wgFileCacheDirectory;
  32                 return $wgFileCacheDirectory;
  33         }
  34
  35         /**
  36          * Get the base cache directory (not specific to this file)
  37          * @return string
  38          */
  39         abstract protected function cacheDirectory();
  40
  41         /**
  42          * Get the path to the cache file
  43          * @return string
  44          */
  45         protected function cachePath() {
  46                 if ( $this->mFilePath !== null ) {
  47                         return $this->mFilePath;
  48                 }
  49
  50                 $dir = $this->cacheDirectory();
  51                 # Build directories (methods include the trailing "/")
  52                 $subDirs = $this->typeSubdirectory() . $this->hashSubdirectory();
  53                 # Avoid extension confusion
  54                 $key = str_replace( '.', '%2E', urlencode( $this->mKey ) );
  55                 # Build the full file path
  56                 $this->mFilePath = "{$dir}/{$subDirs}{$key}.{$this->mExt}";
  57                 if ( $this->useGzip() ) {
  58                         $this->mFilePath .= '.gz';
  59                 }
  60
  61                 return $this->mFilePath;
  62         }
  63
  64         /**
  65          * Check if the cache file exists
  66          * @return bool
  67          */
  68         public function isCached() {
  69                 if ( $this->mCached === null ) {
  70                         $this->mCached = file_exists( $this->cachePath() );
  71                 }
  72                 return $this->mCached;
  73         }
  74
  75         /**
  76          * Get the last-modified timestamp of the cache file
  77          * @return string|false TS_MW timestamp
  78          */
  79         public function cacheTimestamp() {
  80                 $timestamp = filemtime( $this->cachePath() );
  81                 return ( $timestamp !== false )
  82                         ? wfTimestamp( TS_MW, $timestamp )
  83                         : false;
  84         }
  85
  86         /**
  87          * Check if up to date cache file exists
  88          * @param $timestamp string MW_TS timestamp
  89          *
  90          * @return bool
  91          */
  92         public function isCacheGood( $timestamp = '' ) {
  93                 global $wgCacheEpoch;
  94
  95                 if ( !$this->isCached() ) {
  96                         return false;
  97                 }
  98
  99                 $cachetime = $this->cacheTimestamp();
 100                 $good = ( $timestamp <= $cachetime && $wgCacheEpoch <= $cachetime );
 101                 wfDebug( __METHOD__ . ": cachetime $cachetime, touched '{$timestamp}' epoch {$wgCacheEpoch}, good $good\n" );
 102
 103                 return $good;
 104         }
 105
 106         /**
 107          * Check if the cache is gzipped
 108          * @return bool
 109          */
 110         protected function useGzip() {
 111                 return $this->mUseGzip;
 112         }
 113
 114         /**
 115          * Get the uncompressed text from the cache
 116          * @return string
 117          */
 118         public function fetchText() {
 119                 if ( $this->useGzip() ) {
 120                         /* Why is there no gzfile_get_contents() or gzdecode()? */
 121                         return implode( '', gzfile( $this->cachePath() ) );
 122                 } else {
 123                         return file_get_contents( $this->cachePath() );
 124                 }
 125         }
 126
 127         /**
 128          * Save and compress text to the cache
 129          * @return string compressed text
 130          */
 131         public function saveText( $text ) {
 132                 global $wgUseFileCache;
 133
 134                 if ( !$wgUseFileCache ) {
 135                         return false;
 136                 }
 137
 138                 if ( $this->useGzip() ) {
 139                         $text = gzencode( $text );
 140                 }
 141
 142                 $this->checkCacheDirs(); // build parent dir
 143                 if ( !file_put_contents( $this->cachePath(), $text, LOCK_EX ) ) {
 144                         $this->mCached = null;
 145                         return false;
 146                 }
 147
 148                 $this->mCached = true;
 149                 return $text;
 150         }
 151
 152         /**
 153          * Clear the cache for this page
 154          */
 155         public function clearCache() {
 156                 wfSuppressWarnings();
 157                 unlink( $this->cachePath() );
 158                 wfRestoreWarnings();
 159                 $this->mCached = false;
 160         }
 161
 162         /**
 163          * Create parent directors of $this->cachePath()
 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          */
 200         public function incrMissesRecent( WebRequest $request ) {
 201                 global $wgMemc;
 202                 if ( mt_rand( 0, self::MISS_FACTOR - 1 ) == 0 ) {
 203                         # Get a large IP range that should include the user  even if that
 204                         # person's IP address changes
 205                         $ip = $request->getIP();
 206                         if ( !IP::isValid( $ip ) ) {
 207                                 return;
 208                         }
 209                         $ip = IP::isIPv6( $ip )
 210                                 ? IP::sanitizeRange( "$ip/32" )
 211                                 : IP::sanitizeRange( "$ip/16" );
 212
 213                         # Bail out if a request already came from this range...
 214                         $key = wfMemcKey( get_class( $this ), 'attempt', $this->mType, $this->mKey, $ip );
 215                         if ( $wgMemc->get( $key ) ) {
 216                                 return; // possibly the same user
 217                         }
 218                         $wgMemc->set( $key, 1, self::MISS_TTL_SEC );
 219
 220                         # Increment the number of cache misses...
 221                         $key = $this->cacheMissKey();
 222                         if ( $wgMemc->get( $key ) === false ) {
 223                                 $wgMemc->set( $key, 1, self::MISS_TTL_SEC );
 224                         } else {
 225                                 $wgMemc->incr( $key );
 226                         }
 227                 }
 228         }
 229
 230         /**
 231          * Roughly gets the cache misses in the last hour by unique visitors
 232          * @return int
 233          */
 234         public function getMissesRecent() {
 235                 global $wgMemc;
 236                 return self::MISS_FACTOR * $wgMemc->get( $this->cacheMissKey() );
 237         }
 238
 239         /**
 240          * @return string
 241          */
 242         protected function cacheMissKey() {
 243                 return wfMemcKey( get_class( $this ), 'misses', $this->mType, $this->mKey );
 244         }
 245 }