includes/cache/MessageBlobStore.php

   1 <?php
   2 /**
   3  * Resource message blobs storage used by ResourceLoader.
   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  * @author Roan Kattouw
  22  * @author Trevor Parscal
  23  */
  24
  25 /**
  26  * This class provides access to the resource message blobs storage used
  27  * by ResourceLoader.
  28  *
  29  * A message blob is a JSON object containing the interface messages for a
  30  * certain resource in a certain language. These message blobs are cached
  31  * in the msg_resource table and automatically invalidated when one of their
  32  * constituent messages or the resource itself is changed.
  33  */
  34 class MessageBlobStore {
  35         /**
  36          * In-process cache for message blobs.
  37          *
  38          * Keyed by language code, then module name.
  39          *
  40          * @var array
  41          */
  42         protected $blobCache = array();
  43
  44         /* @var ResourceLoader */
  45         protected $resourceloader;
  46
  47         /**
  48          * @param ResourceLoader $resourceloader
  49          */
  50         public function __construct( ResourceLoader $resourceloader = null ) {
  51                 $this->resourceloader = $resourceloader;
  52         }
  53
  54         /**
  55          * Get the singleton instance
  56          *
  57          * @since 1.24
  58          * @deprecated since 1.25
  59          * @return MessageBlobStore
  60          */
  61         public static function getInstance() {
  62                 wfDeprecated( __METHOD__, '1.25' );
  63                 return new self;
  64         }
  65
  66         /**
  67          * Get the message blobs for a set of modules
  68          *
  69          * @param ResourceLoader $resourceLoader
  70          * @param array $modules Array of module objects keyed by module name
  71          * @param string $lang Language code
  72          * @return array An array mapping module names to message blobs
  73          */
  74         public function get( ResourceLoader $resourceLoader, $modules, $lang ) {
  75                 if ( !count( $modules ) ) {
  76                         return array();
  77                 }
  78
  79                 $blobs = array();
  80
  81                 // Try in-process cache
  82                 $missingFromCache = array();
  83                 foreach ( $modules as $name => $module ) {
  84                         if ( isset( $this->blobCache[$lang][$name] ) ) {
  85                                 $blobs[$name] = $this->blobCache[$lang][$name];
  86                         } else {
  87                                 $missingFromCache[] = $name;
  88                         }
  89                 }
  90
  91                 // Try DB cache
  92                 if ( $missingFromCache ) {
  93                         $blobs += $this->getFromDB( $resourceLoader, $missingFromCache, $lang );
  94                 }
  95
  96                 // Generate new blobs for any remaining modules and store in DB
  97                 $missingFromDb = array_diff( array_keys( $modules ), array_keys( $blobs ) );
  98                 foreach ( $missingFromDb as $name ) {
  99                         $blob = $this->insertMessageBlob( $name, $modules[$name], $lang );
 100                         if ( $blob ) {
 101                                 $blobs[$name] = $blob;
 102                         }
 103                 }
 104
 105                 // Update in-process cache
 106                 if ( isset( $this->blobCache[$lang] ) ) {
 107                         $this->blobCache[$lang] += $blobs;
 108                 } else {
 109                         $this->blobCache[$lang] = $blobs;
 110                 }
 111
 112                 return $blobs;
 113         }
 114
 115         /**
 116          * Generate and insert a new message blob. If the blob was already
 117          * present, it is not regenerated; instead, the preexisting blob
 118          * is fetched and returned.
 119          *
 120          * @param string $name Module name
 121          * @param ResourceLoaderModule $module
 122          * @param string $lang Language code
 123          * @return mixed Message blob or false if the module has no messages
 124          */
 125         public function insertMessageBlob( $name, ResourceLoaderModule $module, $lang ) {
 126                 $blob = $this->generateMessageBlob( $module, $lang );
 127
 128                 if ( !$blob ) {
 129                         return false;
 130                 }
 131
 132                 try {
 133                         $dbw = wfGetDB( DB_MASTER );
 134                         $success = $dbw->insert( 'msg_resource', array(
 135                                         'mr_lang' => $lang,
 136                                         'mr_resource' => $name,
 137                                         'mr_blob' => $blob,
 138                                         'mr_timestamp' => $dbw->timestamp()
 139                                 ),
 140                                 __METHOD__,
 141                                 array( 'IGNORE' )
 142                         );
 143
 144                         if ( $success && $dbw->affectedRows() == 0 ) {
 145                                 // Blob was already present, fetch it
 146                                 $blob = $dbw->selectField( 'msg_resource', 'mr_blob', array(
 147                                                 'mr_resource' => $name,
 148                                                 'mr_lang' => $lang,
 149                                         ),
 150                                         __METHOD__
 151                                 );
 152                         }
 153                 } catch ( DBError $e ) {
 154                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 155                 }
 156                 return $blob;
 157         }
 158
 159         /**
 160          * Update the message blob for a given module in a given language
 161          *
 162          * @param string $name Module name
 163          * @param ResourceLoaderModule $module
 164          * @param string $lang Language code
 165          * @return string|null Regenerated message blob, or null if there was no blob for
 166          *   the given module/language pair.
 167          */
 168         public function updateModule( $name, ResourceLoaderModule $module, $lang ) {
 169                 $dbw = wfGetDB( DB_MASTER );
 170                 $row = $dbw->selectRow( 'msg_resource', 'mr_blob',
 171                         array( 'mr_resource' => $name, 'mr_lang' => $lang ),
 172                         __METHOD__
 173                 );
 174                 if ( !$row ) {
 175                         return null;
 176                 }
 177
 178                 $newBlob = $this->generateMessageBlob( $module, $lang );
 179
 180                 try {
 181                         $newRow = array(
 182                                 'mr_resource' => $name,
 183                                 'mr_lang' => $lang,
 184                                 'mr_blob' => $newBlob,
 185                                 'mr_timestamp' => $dbw->timestamp()
 186                         );
 187
 188                         $dbw->replace( 'msg_resource',
 189                                 array( array( 'mr_resource', 'mr_lang' ) ),
 190                                 $newRow, __METHOD__
 191                         );
 192                 } catch ( Exception $e ) {
 193                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 194                 }
 195                 return $newBlob;
 196         }
 197
 198         /**
 199          * Update a single message in all message blobs it occurs in.
 200          *
 201          * @param string $key Message key
 202          */
 203         public function updateMessage( $key ) {
 204                 try {
 205                         $dbw = wfGetDB( DB_MASTER );
 206
 207                         // Keep running until the updates queue is empty.
 208                         // Due to update conflicts, the queue might not be emptied
 209                         // in one iteration.
 210                         $updates = null;
 211                         do {
 212                                 $updates = $this->getUpdatesForMessage( $key, $updates );
 213
 214                                 foreach ( $updates as $k => $update ) {
 215                                         // Update the row on the condition that it
 216                                         // didn't change since we fetched it by putting
 217                                         // the timestamp in the WHERE clause.
 218                                         $success = $dbw->update( 'msg_resource',
 219                                                 array(
 220                                                         'mr_blob' => $update['newBlob'],
 221                                                         'mr_timestamp' => $dbw->timestamp() ),
 222                                                 array(
 223                                                         'mr_resource' => $update['resource'],
 224                                                         'mr_lang' => $update['lang'],
 225                                                         'mr_timestamp' => $update['timestamp'] ),
 226                                                 __METHOD__
 227                                         );
 228
 229                                         // Only requeue conflicted updates.
 230                                         // If update() returned false, don't retry, for
 231                                         // fear of getting into an infinite loop
 232                                         if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 233                                                 // Not conflicted
 234                                                 unset( $updates[$k] );
 235                                         }
 236                                 }
 237                         } while ( count( $updates ) );
 238
 239                 } catch ( Exception $e ) {
 240                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 241                 }
 242         }
 243
 244         public function clear() {
 245                 try {
 246                         // Not using TRUNCATE, because that needs extra permissions,
 247                         // which maybe not granted to the database user.
 248                         $dbw = wfGetDB( DB_MASTER );
 249                         $dbw->delete( 'msg_resource', '*', __METHOD__ );
 250                 } catch ( Exception $e ) {
 251                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 252                 }
 253         }
 254
 255         /**
 256          * @return ResourceLoader
 257          */
 258         protected function getResourceLoader() {
 259                 // For back-compat this class supports instantiation without passing ResourceLoader
 260                 // Lazy-initialise this property because most callers don't need it.
 261                 if ( $this->resourceloader === null ) {
 262                         wfDebug( __CLASS__ . ' created without a ResourceLoader instance' );
 263                         $this->resourceloader = new ResourceLoader();
 264                 }
 265
 266                 return $this->resourceloader;
 267         }
 268
 269         /**
 270          * Create an update queue for updateMessage()
 271          *
 272          * @param string $key Message key
 273          * @param array $prevUpdates Updates queue to refresh or null to build a fresh update queue
 274          * @return array Updates queue
 275          */
 276         private function getUpdatesForMessage( $key, $prevUpdates = null ) {
 277                 $dbw = wfGetDB( DB_MASTER );
 278
 279                 if ( is_null( $prevUpdates ) ) {
 280                         $rl = $this->getResourceLoader();
 281                         $moduleNames = $rl->getModulesByMessage( $key );
 282                         // Fetch all blobs referencing $key
 283                         $res = $dbw->select(
 284                                 array( 'msg_resource' ),
 285                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 286                                 array(
 287                                         'mr_resource' => $moduleNames,
 288                                 ),
 289                                 __METHOD__
 290                         );
 291                 } else {
 292                         // Refetch the blobs referenced by $prevUpdates
 293
 294                         // Reorganize the (resource, lang) pairs in the format
 295                         // expected by makeWhereFrom2d()
 296                         $twoD = array();
 297
 298                         foreach ( $prevUpdates as $update ) {
 299                                 $twoD[$update['resource']][$update['lang']] = true;
 300                         }
 301
 302                         $res = $dbw->select( 'msg_resource',
 303                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 304                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 305                                 __METHOD__
 306                         );
 307                 }
 308
 309                 // Build the new updates queue
 310                 $updates = array();
 311
 312                 foreach ( $res as $row ) {
 313                         $updates[] = array(
 314                                 'resource' => $row->mr_resource,
 315                                 'lang' => $row->mr_lang,
 316                                 'timestamp' => $row->mr_timestamp,
 317                                 'newBlob' => $this->reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 318                         );
 319                 }
 320
 321                 return $updates;
 322         }
 323
 324         /**
 325          * Reencode a message blob with the updated value for a message
 326          *
 327          * @param string $blob Message blob (JSON object)
 328          * @param string $key Message key
 329          * @param string $lang Language code
 330          * @return string Message blob with $key replaced with its new value
 331          */
 332         private function reencodeBlob( $blob, $key, $lang ) {
 333                 $decoded = FormatJson::decode( $blob, true );
 334                 $decoded[$key] = wfMessage( $key )->inLanguage( $lang )->plain();
 335
 336                 return FormatJson::encode( (object)$decoded );
 337         }
 338
 339         /**
 340          * Get the message blobs for a set of modules from the database.
 341          * Modules whose blobs are not in the database are silently dropped.
 342          *
 343          * @param ResourceLoader $resourceLoader
 344          * @param array $modules Array of module names
 345          * @param string $lang Language code
 346          * @throws MWException
 347          * @return array Array mapping module names to blobs
 348          */
 349         private function getFromDB( ResourceLoader $resourceLoader, $modules, $lang ) {
 350                 if ( !count( $modules ) ) {
 351                         return array();
 352                 }
 353
 354                 $retval = array();
 355                 $dbr = wfGetDB( DB_SLAVE );
 356                 $res = $dbr->select( 'msg_resource',
 357                         array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 358                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 359                         __METHOD__
 360                 );
 361
 362                 foreach ( $res as $row ) {
 363                         $module = $resourceLoader->getModule( $row->mr_resource );
 364                         if ( !$module ) {
 365                                 // This shouldn't be possible
 366                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 367                         }
 368
 369                         // Update the module's blob if the list of messages changed
 370                         $blobKeys = array_keys( FormatJson::decode( $row->mr_blob, true ) );
 371                         $moduleMsgs = array_values( array_unique( $module->getMessages() ) );
 372                         if ( $blobKeys !== $moduleMsgs ) {
 373                                 $retval[$row->mr_resource] = $this->updateModule( $row->mr_resource, $module, $lang );
 374                         } else {
 375                                 $retval[$row->mr_resource] = $row->mr_blob;
 376                         }
 377                 }
 378
 379                 return $retval;
 380         }
 381
 382         /**
 383          * Generate the message blob for a given module in a given language.
 384          *
 385          * @param ResourceLoaderModule $module
 386          * @param string $lang Language code
 387          * @return string JSON object
 388          */
 389         private function generateMessageBlob( ResourceLoaderModule $module, $lang ) {
 390                 $messages = array();
 391
 392                 foreach ( $module->getMessages() as $key ) {
 393                         $messages[$key] = wfMessage( $key )->inLanguage( $lang )->plain();
 394                 }
 395
 396                 return FormatJson::encode( (object)$messages );
 397         }
 398 }