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                 wfProfileIn( __METHOD__ );
  60                 if ( !count( $modules ) ) {
  61                         wfProfileOut( __METHOD__ );
  62                         return array();
  63                 }
  64                 // Try getting from the DB first
  65                 $blobs = $this->getFromDB( $resourceLoader, array_keys( $modules ), $lang );
  66
  67                 // Generate blobs for any missing modules and store them in the DB
  68                 $missing = array_diff( array_keys( $modules ), array_keys( $blobs ) );
  69                 foreach ( $missing as $name ) {
  70                         $blob = $this->insertMessageBlob( $name, $modules[$name], $lang );
  71                         if ( $blob ) {
  72                                 $blobs[$name] = $blob;
  73                         }
  74                 }
  75
  76                 wfProfileOut( __METHOD__ );
  77                 return $blobs;
  78         }
  79
  80         /**
  81          * Generate and insert a new message blob. If the blob was already
  82          * present, it is not regenerated; instead, the preexisting blob
  83          * is fetched and returned.
  84          *
  85          * @param string $name Module name
  86          * @param ResourceLoaderModule $module
  87          * @param string $lang Language code
  88          * @return mixed Message blob or false if the module has no messages
  89          */
  90         public function insertMessageBlob( $name, ResourceLoaderModule $module, $lang ) {
  91                 $blob = $this->generateMessageBlob( $module, $lang );
  92
  93                 if ( !$blob ) {
  94                         return false;
  95                 }
  96
  97                 try {
  98                         $dbw = wfGetDB( DB_MASTER );
  99                         $success = $dbw->insert( 'msg_resource', array(
 100                                         'mr_lang' => $lang,
 101                                         'mr_resource' => $name,
 102                                         'mr_blob' => $blob,
 103                                         'mr_timestamp' => $dbw->timestamp()
 104                                 ),
 105                                 __METHOD__,
 106                                 array( 'IGNORE' )
 107                         );
 108
 109                         if ( $success ) {
 110                                 if ( $dbw->affectedRows() == 0 ) {
 111                                         // Blob was already present, fetch it
 112                                         $blob = $dbw->selectField( 'msg_resource', 'mr_blob', array(
 113                                                         'mr_resource' => $name,
 114                                                         'mr_lang' => $lang,
 115                                                 ),
 116                                                 __METHOD__
 117                                         );
 118                                 } else {
 119                                         // Update msg_resource_links
 120                                         $rows = array();
 121
 122                                         foreach ( $module->getMessages() as $key ) {
 123                                                 $rows[] = array(
 124                                                         'mrl_resource' => $name,
 125                                                         'mrl_message' => $key
 126                                                 );
 127                                         }
 128                                         $dbw->insert( 'msg_resource_links', $rows,
 129                                                 __METHOD__, array( 'IGNORE' )
 130                                         );
 131                                 }
 132                         }
 133                 } catch ( Exception $e ) {
 134                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 135                 }
 136                 return $blob;
 137         }
 138
 139         /**
 140          * Update the message blob for a given module in a given language
 141          *
 142          * @param string $name Module name
 143          * @param ResourceLoaderModule $module
 144          * @param string $lang Language code
 145          * @return string Regenerated message blob, or null if there was no blob for
 146          *   the given module/language pair.
 147          */
 148         public function updateModule( $name, ResourceLoaderModule $module, $lang ) {
 149                 $dbw = wfGetDB( DB_MASTER );
 150                 $row = $dbw->selectRow( 'msg_resource', 'mr_blob',
 151                         array( 'mr_resource' => $name, 'mr_lang' => $lang ),
 152                         __METHOD__
 153                 );
 154                 if ( !$row ) {
 155                         return null;
 156                 }
 157
 158                 // Save the old and new blobs for later
 159                 $oldBlob = $row->mr_blob;
 160                 $newBlob = $this->generateMessageBlob( $module, $lang );
 161
 162                 try {
 163                         $newRow = array(
 164                                 'mr_resource' => $name,
 165                                 'mr_lang' => $lang,
 166                                 'mr_blob' => $newBlob,
 167                                 'mr_timestamp' => $dbw->timestamp()
 168                         );
 169
 170                         $dbw->replace( 'msg_resource',
 171                                 array( array( 'mr_resource', 'mr_lang' ) ),
 172                                 $newRow, __METHOD__
 173                         );
 174
 175                         // Figure out which messages were added and removed
 176                         $oldMessages = array_keys( FormatJson::decode( $oldBlob, true ) );
 177                         $newMessages = array_keys( FormatJson::decode( $newBlob, true ) );
 178                         $added = array_diff( $newMessages, $oldMessages );
 179                         $removed = array_diff( $oldMessages, $newMessages );
 180
 181                         // Delete removed messages, insert added ones
 182                         if ( $removed ) {
 183                                 $dbw->delete( 'msg_resource_links', array(
 184                                                 'mrl_resource' => $name,
 185                                                 'mrl_message' => $removed
 186                                         ), __METHOD__
 187                                 );
 188                         }
 189
 190                         $newLinksRows = array();
 191
 192                         foreach ( $added as $message ) {
 193                                 $newLinksRows[] = array(
 194                                         'mrl_resource' => $name,
 195                                         'mrl_message' => $message
 196                                 );
 197                         }
 198
 199                         if ( $newLinksRows ) {
 200                                 $dbw->insert( 'msg_resource_links', $newLinksRows, __METHOD__,
 201                                         array( 'IGNORE' ) // just in case
 202                                 );
 203                         }
 204                 } catch ( Exception $e ) {
 205                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 206                 }
 207                 return $newBlob;
 208         }
 209
 210         /**
 211          * Update a single message in all message blobs it occurs in.
 212          *
 213          * @param string $key Message key
 214          */
 215         public function updateMessage( $key ) {
 216                 try {
 217                         $dbw = wfGetDB( DB_MASTER );
 218
 219                         // Keep running until the updates queue is empty.
 220                         // Due to update conflicts, the queue might not be emptied
 221                         // in one iteration.
 222                         $updates = null;
 223                         do {
 224                                 $updates = $this->getUpdatesForMessage( $key, $updates );
 225
 226                                 foreach ( $updates as $k => $update ) {
 227                                         // Update the row on the condition that it
 228                                         // didn't change since we fetched it by putting
 229                                         // the timestamp in the WHERE clause.
 230                                         $success = $dbw->update( 'msg_resource',
 231                                                 array(
 232                                                         'mr_blob' => $update['newBlob'],
 233                                                         'mr_timestamp' => $dbw->timestamp() ),
 234                                                 array(
 235                                                         'mr_resource' => $update['resource'],
 236                                                         'mr_lang' => $update['lang'],
 237                                                         'mr_timestamp' => $update['timestamp'] ),
 238                                                 __METHOD__
 239                                         );
 240
 241                                         // Only requeue conflicted updates.
 242                                         // If update() returned false, don't retry, for
 243                                         // fear of getting into an infinite loop
 244                                         if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 245                                                 // Not conflicted
 246                                                 unset( $updates[$k] );
 247                                         }
 248                                 }
 249                         } while ( count( $updates ) );
 250
 251                         // No need to update msg_resource_links because we didn't add
 252                         // or remove any messages, we just changed their contents.
 253                 } catch ( Exception $e ) {
 254                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 255                 }
 256         }
 257
 258         public function clear() {
 259                 // TODO: Give this some more thought
 260                 try {
 261                         // Not using TRUNCATE, because that needs extra permissions,
 262                         // which maybe not granted to the database user.
 263                         $dbw = wfGetDB( DB_MASTER );
 264                         $dbw->delete( 'msg_resource', '*', __METHOD__ );
 265                         $dbw->delete( 'msg_resource_links', '*', __METHOD__ );
 266                 } catch ( Exception $e ) {
 267                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 268                 }
 269         }
 270
 271         /**
 272          * Create an update queue for updateMessage()
 273          *
 274          * @param string $key Message key
 275          * @param array $prevUpdates Updates queue to refresh or null to build a fresh update queue
 276          * @return array Updates queue
 277          */
 278         private function getUpdatesForMessage( $key, $prevUpdates = null ) {
 279                 $dbw = wfGetDB( DB_MASTER );
 280
 281                 if ( is_null( $prevUpdates ) ) {
 282                         // Fetch all blobs referencing $key
 283                         $res = $dbw->select(
 284                                 array( 'msg_resource', 'msg_resource_links' ),
 285                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 286                                 array( 'mrl_message' => $key, 'mr_resource=mrl_resource' ),
 287                                 __METHOD__
 288                         );
 289                 } else {
 290                         // Refetch the blobs referenced by $prevUpdates
 291
 292                         // Reorganize the (resource, lang) pairs in the format
 293                         // expected by makeWhereFrom2d()
 294                         $twoD = array();
 295
 296                         foreach ( $prevUpdates as $update ) {
 297                                 $twoD[$update['resource']][$update['lang']] = true;
 298                         }
 299
 300                         $res = $dbw->select( 'msg_resource',
 301                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 302                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 303                                 __METHOD__
 304                         );
 305                 }
 306
 307                 // Build the new updates queue
 308                 $updates = array();
 309
 310                 foreach ( $res as $row ) {
 311                         $updates[] = array(
 312                                 'resource' => $row->mr_resource,
 313                                 'lang' => $row->mr_lang,
 314                                 'timestamp' => $row->mr_timestamp,
 315                                 'newBlob' => $this->reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 316                         );
 317                 }
 318
 319                 return $updates;
 320         }
 321
 322         /**
 323          * Reencode a message blob with the updated value for a message
 324          *
 325          * @param string $blob Message blob (JSON object)
 326          * @param string $key Message key
 327          * @param string $lang Language code
 328          * @return string Message blob with $key replaced with its new value
 329          */
 330         private function reencodeBlob( $blob, $key, $lang ) {
 331                 $decoded = FormatJson::decode( $blob, true );
 332                 $decoded[$key] = wfMessage( $key )->inLanguage( $lang )->plain();
 333
 334                 return FormatJson::encode( (object)$decoded );
 335         }
 336
 337         /**
 338          * Get the message blobs for a set of modules from the database.
 339          * Modules whose blobs are not in the database are silently dropped.
 340          *
 341          * @param ResourceLoader $resourceLoader
 342          * @param array $modules Array of module names
 343          * @param string $lang Language code
 344          * @throws MWException
 345          * @return array Array mapping module names to blobs
 346          */
 347         private function getFromDB( ResourceLoader $resourceLoader, $modules, $lang ) {
 348                 $config = $resourceLoader->getConfig();
 349                 $retval = array();
 350                 $dbr = wfGetDB( DB_SLAVE );
 351                 $res = $dbr->select( 'msg_resource',
 352                         array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 353                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 354                         __METHOD__
 355                 );
 356
 357                 foreach ( $res as $row ) {
 358                         $module = $resourceLoader->getModule( $row->mr_resource );
 359                         if ( !$module ) {
 360                                 // This shouldn't be possible
 361                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 362                         }
 363
 364                         // Update the module's blobs if the set of messages changed or if the blob is
 365                         // older than the CacheEpoch setting
 366                         $keys = array_keys( FormatJson::decode( $row->mr_blob, true ) );
 367                         $values = array_values( array_unique( $module->getMessages() ) );
 368                         if ( $keys !== $values
 369                                 || wfTimestamp( TS_MW, $row->mr_timestamp ) <= $config->get( 'CacheEpoch' )
 370                         ) {
 371                                 $retval[$row->mr_resource] = $this->updateModule( $row->mr_resource, $module, $lang );
 372                         } else {
 373                                 $retval[$row->mr_resource] = $row->mr_blob;
 374                         }
 375                 }
 376
 377                 return $retval;
 378         }
 379
 380         /**
 381          * Generate the message blob for a given module in a given language.
 382          *
 383          * @param ResourceLoaderModule $module
 384          * @param string $lang Language code
 385          * @return string JSON object
 386          */
 387         private function generateMessageBlob( ResourceLoaderModule $module, $lang ) {
 388                 $messages = array();
 389
 390                 foreach ( $module->getMessages() as $key ) {
 391                         $messages[$key] = wfMessage( $key )->inLanguage( $lang )->plain();
 392                 }
 393
 394                 return FormatJson::encode( (object)$messages );
 395         }
 396 }