includes/MessageBlobStore.php

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