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 message blobs for a set of modules
  56          *
  57          * @param ResourceLoader $resourceLoader
  58          * @param array $modules Array of module objects keyed by module name
  59          * @param string $lang Language code
  60          * @return array An array mapping module names to message blobs
  61          */
  62         public function get( ResourceLoader $resourceLoader, $modules, $lang ) {
  63                 if ( !count( $modules ) ) {
  64                         return array();
  65                 }
  66
  67                 $blobs = array();
  68
  69                 // Try in-process cache
  70                 $missingFromCache = array();
  71                 foreach ( $modules as $name => $module ) {
  72                         if ( isset( $this->blobCache[$lang][$name] ) ) {
  73                                 $blobs[$name] = $this->blobCache[$lang][$name];
  74                         } else {
  75                                 $missingFromCache[] = $name;
  76                         }
  77                 }
  78
  79                 // Try DB cache
  80                 if ( $missingFromCache ) {
  81                         $blobs += $this->getFromDB( $resourceLoader, $missingFromCache, $lang );
  82                 }
  83
  84                 // Generate new blobs for any remaining modules and store in DB
  85                 $missingFromDb = array_diff( array_keys( $modules ), array_keys( $blobs ) );
  86                 foreach ( $missingFromDb as $name ) {
  87                         $blob = $this->insertMessageBlob( $name, $modules[$name], $lang );
  88                         if ( $blob ) {
  89                                 $blobs[$name] = $blob;
  90                         }
  91                 }
  92
  93                 // Update in-process cache
  94                 if ( isset( $this->blobCache[$lang] ) ) {
  95                         $this->blobCache[$lang] += $blobs;
  96                 } else {
  97                         $this->blobCache[$lang] = $blobs;
  98                 }
  99
 100                 return $blobs;
 101         }
 102
 103         /**
 104          * Generate and insert a new message blob. If the blob was already
 105          * present, it is not regenerated; instead, the preexisting blob
 106          * is fetched and returned.
 107          *
 108          * @param string $name Module name
 109          * @param ResourceLoaderModule $module
 110          * @param string $lang Language code
 111          * @return mixed Message blob or false if the module has no messages
 112          */
 113         public function insertMessageBlob( $name, ResourceLoaderModule $module, $lang ) {
 114                 $blob = $this->generateMessageBlob( $module, $lang );
 115
 116                 if ( !$blob ) {
 117                         return false;
 118                 }
 119
 120                 try {
 121                         $dbw = wfGetDB( DB_MASTER );
 122                         $success = $dbw->insert( 'msg_resource', array(
 123                                         'mr_lang' => $lang,
 124                                         'mr_resource' => $name,
 125                                         'mr_blob' => $blob,
 126                                         'mr_timestamp' => $dbw->timestamp()
 127                                 ),
 128                                 __METHOD__,
 129                                 array( 'IGNORE' )
 130                         );
 131
 132                         if ( $success && $dbw->affectedRows() == 0 ) {
 133                                 // Blob was already present, fetch it
 134                                 $blob = $dbw->selectField( 'msg_resource', 'mr_blob', array(
 135                                                 'mr_resource' => $name,
 136                                                 'mr_lang' => $lang,
 137                                         ),
 138                                         __METHOD__
 139                                 );
 140                         }
 141                 } catch ( DBError $e ) {
 142                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 143                 }
 144                 return $blob;
 145         }
 146
 147         /**
 148          * Update the message blob for a given module in a given language
 149          *
 150          * @param string $name Module name
 151          * @param ResourceLoaderModule $module
 152          * @param string $lang Language code
 153          * @return string|null Regenerated message blob, or null if there was no blob for
 154          *   the given module/language pair.
 155          */
 156         public function updateModule( $name, ResourceLoaderModule $module, $lang ) {
 157                 $dbw = wfGetDB( DB_MASTER );
 158                 $row = $dbw->selectRow( 'msg_resource', 'mr_blob',
 159                         array( 'mr_resource' => $name, 'mr_lang' => $lang ),
 160                         __METHOD__
 161                 );
 162                 if ( !$row ) {
 163                         return null;
 164                 }
 165
 166                 $newBlob = $this->generateMessageBlob( $module, $lang );
 167
 168                 try {
 169                         $newRow = array(
 170                                 'mr_resource' => $name,
 171                                 'mr_lang' => $lang,
 172                                 'mr_blob' => $newBlob,
 173                                 'mr_timestamp' => $dbw->timestamp()
 174                         );
 175
 176                         $dbw->replace( 'msg_resource',
 177                                 array( array( 'mr_resource', 'mr_lang' ) ),
 178                                 $newRow, __METHOD__
 179                         );
 180                 } catch ( Exception $e ) {
 181                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 182                 }
 183                 return $newBlob;
 184         }
 185
 186         /**
 187          * Update a single message in all message blobs it occurs in.
 188          *
 189          * @param string $key Message key
 190          */
 191         public function updateMessage( $key ) {
 192                 try {
 193                         $dbw = wfGetDB( DB_MASTER );
 194
 195                         // Keep running until the updates queue is empty.
 196                         // Due to update conflicts, the queue might not be emptied
 197                         // in one iteration.
 198                         $updates = null;
 199                         do {
 200                                 $updates = $this->getUpdatesForMessage( $key, $updates );
 201
 202                                 foreach ( $updates as $k => $update ) {
 203                                         // Update the row on the condition that it
 204                                         // didn't change since we fetched it by putting
 205                                         // the timestamp in the WHERE clause.
 206                                         $success = $dbw->update( 'msg_resource',
 207                                                 array(
 208                                                         'mr_blob' => $update['newBlob'],
 209                                                         'mr_timestamp' => $dbw->timestamp() ),
 210                                                 array(
 211                                                         'mr_resource' => $update['resource'],
 212                                                         'mr_lang' => $update['lang'],
 213                                                         'mr_timestamp' => $update['timestamp'] ),
 214                                                 __METHOD__
 215                                         );
 216
 217                                         // Only requeue conflicted updates.
 218                                         // If update() returned false, don't retry, for
 219                                         // fear of getting into an infinite loop
 220                                         if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 221                                                 // Not conflicted
 222                                                 unset( $updates[$k] );
 223                                         }
 224                                 }
 225                         } while ( count( $updates ) );
 226
 227                 } catch ( Exception $e ) {
 228                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 229                 }
 230         }
 231
 232         public function clear() {
 233                 try {
 234                         // Not using TRUNCATE, because that needs extra permissions,
 235                         // which maybe not granted to the database user.
 236                         $dbw = wfGetDB( DB_MASTER );
 237                         $dbw->delete( 'msg_resource', '*', __METHOD__ );
 238                 } catch ( Exception $e ) {
 239                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 240                 }
 241         }
 242
 243         /**
 244          * @return ResourceLoader
 245          */
 246         protected function getResourceLoader() {
 247                 // For back-compat this class supports instantiation without passing ResourceLoader
 248                 // Lazy-initialise this property because most callers don't need it.
 249                 if ( $this->resourceloader === null ) {
 250                         wfDebug( __CLASS__ . ' created without a ResourceLoader instance' );
 251                         $this->resourceloader = new ResourceLoader();
 252                 }
 253
 254                 return $this->resourceloader;
 255         }
 256
 257         /**
 258          * Create an update queue for updateMessage()
 259          *
 260          * @param string $key Message key
 261          * @param array $prevUpdates Updates queue to refresh or null to build a fresh update queue
 262          * @return array Updates queue
 263          */
 264         private function getUpdatesForMessage( $key, $prevUpdates = null ) {
 265                 $dbw = wfGetDB( DB_MASTER );
 266
 267                 if ( is_null( $prevUpdates ) ) {
 268                         $rl = $this->getResourceLoader();
 269                         $moduleNames = $rl->getModulesByMessage( $key );
 270                         // Fetch all blobs referencing $key
 271                         $res = $dbw->select(
 272                                 array( 'msg_resource' ),
 273                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 274                                 array(
 275                                         'mr_resource' => $moduleNames,
 276                                 ),
 277                                 __METHOD__
 278                         );
 279                 } else {
 280                         // Refetch the blobs referenced by $prevUpdates
 281
 282                         // Reorganize the (resource, lang) pairs in the format
 283                         // expected by makeWhereFrom2d()
 284                         $twoD = array();
 285
 286                         foreach ( $prevUpdates as $update ) {
 287                                 $twoD[$update['resource']][$update['lang']] = true;
 288                         }
 289
 290                         $res = $dbw->select( 'msg_resource',
 291                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 292                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 293                                 __METHOD__
 294                         );
 295                 }
 296
 297                 // Build the new updates queue
 298                 $updates = array();
 299
 300                 foreach ( $res as $row ) {
 301                         $updates[] = array(
 302                                 'resource' => $row->mr_resource,
 303                                 'lang' => $row->mr_lang,
 304                                 'timestamp' => $row->mr_timestamp,
 305                                 'newBlob' => $this->reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 306                         );
 307                 }
 308
 309                 return $updates;
 310         }
 311
 312         /**
 313          * @param string $key Message key
 314          * @param string $lang Language code
 315          * @return string
 316          */
 317         private function fetchMessage( $key, $lang ) {
 318                 $message = wfMessage( $key )->inLanguage( $lang );
 319                 if ( !$message->exists() ) {
 320                         wfDebugLog( 'resourceloader', __METHOD__ . " failed to find: '$key' ($lang)" );
 321                 }
 322                 return $message->plain();
 323         }
 324
 325         /**
 326          * Reencode a message blob with the updated value for a message
 327          *
 328          * @param string $blob Message blob (JSON object)
 329          * @param string $key Message key
 330          * @param string $lang Language code
 331          * @return string Message blob with $key replaced with its new value
 332          */
 333         private function reencodeBlob( $blob, $key, $lang ) {
 334                 $decoded = FormatJson::decode( $blob, true );
 335                 $decoded[$key] = $this->fetchMessage( $key, $lang );
 336                 return FormatJson::encode( (object)$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] = $this->fetchMessage( $key, $lang );
 394                 }
 395
 396                 return FormatJson::encode( (object)$messages );
 397         }
 398 }