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