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