includes/CacheHelper.php

   1 <?php
   2 /**
   3  * Cache of various elements in a single cache entry.
   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  * @licence GNU GPL v2 or later
  22  * @author Jeroen De Dauw < jeroendedauw@gmail.com >
  23  */
  24
  25 /**
  26  * Interface for all classes implementing CacheHelper functionality.
  27  *
  28  * @since 1.20
  29  */
  30 interface ICacheHelper {
  31
  32         /**
  33          * Sets if the cache should be enabled or not.
  34          *
  35          * @since 1.20
  36          * @param boolean $cacheEnabled
  37          */
  38         function setCacheEnabled( $cacheEnabled );
  39
  40         /**
  41          * Initializes the caching.
  42          * Should be called before the first time anything is added via addCachedHTML.
  43          *
  44          * @since 1.20
  45          *
  46          * @param integer|null $cacheExpiry Sets the cache expiry, either ttl in seconds or unix timestamp.
  47          * @param boolean|null $cacheEnabled Sets if the cache should be enabled or not.
  48          */
  49         function startCache( $cacheExpiry = null, $cacheEnabled = null );
  50
  51         /**
  52          * Get a cached value if available or compute it if not and then cache it if possible.
  53          * The provided $computeFunction is only called when the computation needs to happen
  54          * and should return a result value. $args are arguments that will be passed to the
  55          * compute function when called.
  56          *
  57          * @since 1.20
  58          *
  59          * @param {function} $computeFunction
  60          * @param array|mixed $args
  61          * @param string|null $key
  62          *
  63          * @return mixed
  64          */
  65         function getCachedValue( $computeFunction, $args = array(), $key = null );
  66
  67         /**
  68          * Saves the HTML to the cache in case it got recomputed.
  69          * Should be called after the last time anything is added via addCachedHTML.
  70          *
  71          * @since 1.20
  72          */
  73         function saveCache();
  74
  75         /**
  76          * Sets the time to live for the cache, in seconds or a unix timestamp indicating the point of expiry..
  77          *
  78          * @since 1.20
  79          *
  80          * @param integer $cacheExpiry
  81          */
  82         function setExpiry( $cacheExpiry );
  83
  84 }
  85
  86 /**
  87  * Helper class for caching various elements in a single cache entry.
  88  *
  89  * To get a cached value or compute it, use getCachedValue like this:
  90  * $this->getCachedValue( $callback );
  91  *
  92  * To add HTML that should be cached, use addCachedHTML like this:
  93  * $this->addCachedHTML( $callback );
  94  *
  95  * The callback function is only called when needed, so do all your expensive
  96  * computations here. This function should returns the HTML to be cached.
  97  * It should not add anything to the PageOutput object!
  98  *
  99  * Before the first addCachedHTML call, you should call $this->startCache();
 100  * After adding the last HTML that should be cached, call $this->saveCache();
 101  *
 102  * @since 1.20
 103  */
 104 class CacheHelper implements ICacheHelper {
 105
 106         /**
 107          * The time to live for the cache, in seconds or a unix timestamp indicating the point of expiry.
 108          *
 109          * @since 1.20
 110          * @var integer
 111          */
 112         protected $cacheExpiry = 3600;
 113
 114         /**
 115          * List of HTML chunks to be cached (if !hasCached) or that where cached (of hasCached).
 116          * If not cached already, then the newly computed chunks are added here,
 117          * if it as cached already, chunks are removed from this list as they are needed.
 118          *
 119          * @since 1.20
 120          * @var array
 121          */
 122         protected $cachedChunks;
 123
 124         /**
 125          * Indicates if the to be cached content was already cached.
 126          * Null if this information is not available yet.
 127          *
 128          * @since 1.20
 129          * @var boolean|null
 130          */
 131         protected $hasCached = null;
 132
 133         /**
 134          * If the cache is enabled or not.
 135          *
 136          * @since 1.20
 137          * @var boolean
 138          */
 139         protected $cacheEnabled = true;
 140
 141         /**
 142          * Function that gets called when initialization is done.
 143          *
 144          * @since 1.20
 145          * @var function
 146          */
 147         protected $onInitHandler = false;
 148
 149         /**
 150          * Sets if the cache should be enabled or not.
 151          *
 152          * @since 1.20
 153          * @param boolean $cacheEnabled
 154          */
 155         public function setCacheEnabled( $cacheEnabled ) {
 156                 $this->cacheEnabled = $cacheEnabled;
 157         }
 158
 159         /**
 160          * Initializes the caching.
 161          * Should be called before the first time anything is added via addCachedHTML.
 162          *
 163          * @since 1.20
 164          *
 165          * @param integer|null $cacheExpiry Sets the cache expiry, either ttl in seconds or unix timestamp.
 166          * @param boolean|null $cacheEnabled Sets if the cache should be enabled or not.
 167          */
 168         public function startCache( $cacheExpiry = null, $cacheEnabled = null ) {
 169                 if ( is_null( $this->hasCached ) ) {
 170                         if ( !is_null( $cacheExpiry ) ) {
 171                                 $this->cacheExpiry = $cacheExpiry;
 172                         }
 173
 174                         if ( !is_null( $cacheEnabled ) ) {
 175                                 $this->setCacheEnabled( $cacheEnabled );
 176                         }
 177
 178                         $this->initCaching();
 179                 }
 180         }
 181
 182         /**
 183          * Returns a message that notifies the user he/she is looking at
 184          * a cached version of the page, including a refresh link.
 185          *
 186          * @since 1.20
 187          *
 188          * @param IContextSource $context
 189          * @param boolean $includePurgeLink
 190          *
 191          * @return string
 192          */
 193         public function getCachedNotice( IContextSource $context, $includePurgeLink = true ) {
 194                 if ( $this->cacheExpiry < 86400 * 3650 ) {
 195                         $message = $context->msg(
 196                                 'cachedspecial-viewing-cached-ttl',
 197                                 $context->getLanguage()->formatDuration( $this->cacheExpiry )
 198                         )->escaped();
 199                 }
 200                 else {
 201                         $message = $context->msg(
 202                                 'cachedspecial-viewing-cached-ts'
 203                         )->escaped();
 204                 }
 205
 206                 if ( $includePurgeLink ) {
 207                         $refreshArgs = $context->getRequest()->getQueryValues();
 208                         unset( $refreshArgs['title'] );
 209                         $refreshArgs['action'] = 'purge';
 210
 211                         $subPage = $context->getTitle()->getFullText();
 212                         $subPage = explode( '/', $subPage, 2 );
 213                         $subPage = count( $subPage ) > 1 ? $subPage[1] : false;
 214
 215                         $message .= ' ' . Linker::link(
 216                                 $context->getTitle( $subPage ),
 217                                 $context->msg( 'cachedspecial-refresh-now' )->escaped(),
 218                                 array(),
 219                                 $refreshArgs
 220                         );
 221                 }
 222
 223                 return $message;
 224         }
 225
 226         /**
 227          * Initializes the caching if not already done so.
 228          * Should be called before any of the caching functionality is used.
 229          *
 230          * @since 1.20
 231          */
 232         protected function initCaching() {
 233                 if ( $this->cacheEnabled && is_null( $this->hasCached ) ) {
 234                         $cachedChunks = wfGetCache( CACHE_ANYTHING )->get( $this->getCacheKeyString() );
 235
 236                         $this->hasCached = is_array( $cachedChunks );
 237                         $this->cachedChunks = $this->hasCached ? $cachedChunks : array();
 238
 239                         if ( $this->onInitHandler !== false ) {
 240                                 call_user_func( $this->onInitHandler, $this->hasCached );
 241                         }
 242                 }
 243         }
 244
 245         /**
 246          * Get a cached value if available or compute it if not and then cache it if possible.
 247          * The provided $computeFunction is only called when the computation needs to happen
 248          * and should return a result value. $args are arguments that will be passed to the
 249          * compute function when called.
 250          *
 251          * @since 1.20
 252          *
 253          * @param {function} $computeFunction
 254          * @param array|mixed $args
 255          * @param string|null $key
 256          *
 257          * @return mixed
 258          */
 259         public function getCachedValue( $computeFunction, $args = array(), $key = null ) {
 260                 $this->initCaching();
 261
 262                 if ( $this->cacheEnabled && $this->hasCached ) {
 263                         $value = null;
 264
 265                         if ( is_null( $key ) ) {
 266                                 $itemKey = array_keys( array_slice( $this->cachedChunks, 0, 1 ) );
 267                                 $itemKey = array_shift( $itemKey );
 268
 269                                 if ( !is_integer( $itemKey ) ) {
 270                                         wfWarn( "Attempted to get item with non-numeric key while the next item in the queue has a key ($itemKey) in " . __METHOD__ );
 271                                 }
 272                                 elseif ( is_null( $itemKey ) ) {
 273                                         wfWarn( "Attempted to get an item while the queue is empty in " . __METHOD__ );
 274                                 }
 275                                 else {
 276                                         $value = array_shift( $this->cachedChunks );
 277                                 }
 278                         }
 279                         else {
 280                                 if ( array_key_exists( $key, $this->cachedChunks ) ) {
 281                                         $value = $this->cachedChunks[$key];
 282                                         unset( $this->cachedChunks[$key] );
 283                                 }
 284                                 else {
 285                                         wfWarn( "There is no item with key '$key' in this->cachedChunks in " . __METHOD__ );
 286                                 }
 287                         }
 288                 }
 289                 else {
 290                         if ( !is_array( $args ) ) {
 291                                 $args = array( $args );
 292                         }
 293
 294                         $value = call_user_func_array( $computeFunction, $args );
 295
 296                         if ( $this->cacheEnabled ) {
 297                                 if ( is_null( $key ) ) {
 298                                         $this->cachedChunks[] = $value;
 299                                 }
 300                                 else {
 301                                         $this->cachedChunks[$key] = $value;
 302                                 }
 303                         }
 304                 }
 305
 306                 return $value;
 307         }
 308
 309         /**
 310          * Saves the HTML to the cache in case it got recomputed.
 311          * Should be called after the last time anything is added via addCachedHTML.
 312          *
 313          * @since 1.20
 314          */
 315         public function saveCache() {
 316                 if ( $this->cacheEnabled && $this->hasCached === false && !empty( $this->cachedChunks ) ) {
 317                         wfGetCache( CACHE_ANYTHING )->set( $this->getCacheKeyString(), $this->cachedChunks, $this->cacheExpiry );
 318                 }
 319         }
 320
 321         /**
 322          * Sets the time to live for the cache, in seconds or a unix timestamp indicating the point of expiry..
 323          *
 324          * @since 1.20
 325          *
 326          * @param integer $cacheExpiry
 327          */
 328         public function setExpiry( $cacheExpiry ) {
 329                 $this->cacheExpiry = $cacheExpiry;
 330         }
 331
 332         /**
 333          * Returns the cache key to use to cache this page's HTML output.
 334          * Is constructed from the special page name and language code.
 335          *
 336          * @since 1.20
 337          *
 338          * @return string
 339          */
 340         protected function getCacheKeyString() {
 341                 return call_user_func_array( 'wfMemcKey', $this->cacheKey );
 342         }
 343
 344         /**
 345          * Sets the cache key that should be used.
 346          *
 347          * @since 1.20
 348          *
 349          * @param array $cacheKey
 350          */
 351         public function setCacheKey( array $cacheKey ) {
 352                 $this->cacheKey = $cacheKey;
 353         }
 354
 355         /**
 356          * Rebuild the content, even if it's already cached.
 357          * This effectively has the same effect as purging the cache,
 358          * since it will be overridden with the new value on the next request.
 359          *
 360          * @since 1.20
 361          */
 362         public function rebuildOnDemand() {
 363                 $this->hasCached = false;
 364         }
 365
 366         /**
 367          * Sets a function that gets called when initialization of the cache is done.
 368          *
 369          * @since 1.20
 370          *
 371          * @param $handlerFunction
 372          */
 373         public function setOnInitializedHandler( $handlerFunction ) {
 374                 $this->onInitHandler = $handlerFunction;
 375         }
 376
 377 }