includes/cache/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          * 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         /**
  45          * Get the singleton instance
  46          *
  47          * @since 1.24
  48          * @deprecated since 1.25
  49          * @return MessageBlobStore
  50          */
  51         public static function getInstance() {
  52                 wfDeprecated( __METHOD__, '1.25' );
  53                 return new self;
  54         }
  55
  56         /**
  57          * Get the message blobs for a set of modules
  58          *
  59          * @param ResourceLoader $resourceLoader
  60          * @param array $modules Array of module objects keyed by module name
  61          * @param string $lang Language code
  62          * @return array An array mapping module names to message blobs
  63          */
  64         public function get( ResourceLoader $resourceLoader, $modules, $lang ) {
  65                 if ( !count( $modules ) ) {
  66                         return array();
  67                 }
  68
  69                 $blobs = array();
  70
  71                 // Try in-process cache
  72                 $missingFromCache = array();
  73                 foreach ( $modules as $name => $module ) {
  74                         if ( isset( $this->blobCache[$lang][$name] ) ) {
  75                                 $blobs[$name] = $this->blobCache[$lang][$name];
  76                         } else {
  77                                 $missingFromCache[] = $name;
  78                         }
  79                 }
  80
  81                 // Try DB cache
  82                 if ( $missingFromCache ) {
  83                         $blobs += $this->getFromDB( $resourceLoader, $missingFromCache, $lang );
  84                 }
  85
  86                 // Generate new blobs for any remaining modules and store in DB
  87                 $missingFromDb = array_diff( array_keys( $modules ), array_keys( $blobs ) );
  88                 foreach ( $missingFromDb as $name ) {
  89                         $blob = $this->insertMessageBlob( $name, $modules[$name], $lang );
  90                         if ( $blob ) {
  91                                 $blobs[$name] = $blob;
  92                         }
  93                 }
  94
  95                 // Update in-process cache
  96                 if ( isset( $this->blobCache[$lang] ) ) {
  97                         $this->blobCache[$lang] += $blobs;
  98                 } else {
  99                         $this->blobCache[$lang] = $blobs;
 100                 }
 101
 102                 return $blobs;
 103         }
 104
 105         /**
 106          * Generate and insert a new message blob. If the blob was already
 107          * present, it is not regenerated; instead, the preexisting blob
 108          * is fetched and returned.
 109          *
 110          * @param string $name Module name
 111          * @param ResourceLoaderModule $module
 112          * @param string $lang Language code
 113          * @return mixed Message blob or false if the module has no messages
 114          */
 115         public function insertMessageBlob( $name, ResourceLoaderModule $module, $lang ) {
 116                 $blob = $this->generateMessageBlob( $module, $lang );
 117
 118                 if ( !$blob ) {
 119                         return false;
 120                 }
 121
 122                 try {
 123                         $dbw = wfGetDB( DB_MASTER );
 124                         $success = $dbw->insert( 'msg_resource', array(
 125                                         'mr_lang' => $lang,
 126                                         'mr_resource' => $name,
 127                                         'mr_blob' => $blob,
 128                                         'mr_timestamp' => $dbw->timestamp()
 129                                 ),
 130                                 __METHOD__,
 131                                 array( 'IGNORE' )
 132                         );
 133
 134                         if ( $success ) {
 135                                 if ( $dbw->affectedRows() == 0 ) {
 136                                         // Blob was already present, fetch it
 137                                         $blob = $dbw->selectField( 'msg_resource', 'mr_blob', array(
 138                                                         'mr_resource' => $name,
 139                                                         'mr_lang' => $lang,
 140                                                 ),
 141                                                 __METHOD__
 142                                         );
 143                                 } else {
 144                                         // Update msg_resource_links
 145                                         $rows = array();
 146
 147                                         foreach ( $module->getMessages() as $key ) {
 148                                                 $rows[] = array(
 149                                                         'mrl_resource' => $name,
 150                                                         'mrl_message' => $key
 151                                                 );
 152                                         }
 153                                         $dbw->insert( 'msg_resource_links', $rows,
 154                                                 __METHOD__, array( 'IGNORE' )
 155                                         );
 156                                 }
 157                         }
 158                 } catch ( DBError $e ) {
 159                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 160                 }
 161                 return $blob;
 162         }
 163
 164         /**
 165          * Update the message blob for a given module in a given language
 166          *
 167          * @param string $name Module name
 168          * @param ResourceLoaderModule $module
 169          * @param string $lang Language code
 170          * @return string Regenerated message blob, or null if there was no blob for
 171          *   the given module/language pair.
 172          */
 173         public function updateModule( $name, ResourceLoaderModule $module, $lang ) {
 174                 $dbw = wfGetDB( DB_MASTER );
 175                 $row = $dbw->selectRow( 'msg_resource', 'mr_blob',
 176                         array( 'mr_resource' => $name, 'mr_lang' => $lang ),
 177                         __METHOD__
 178                 );
 179                 if ( !$row ) {
 180                         return null;
 181                 }
 182
 183                 // Save the old and new blobs for later
 184                 $oldBlob = $row->mr_blob;
 185                 $newBlob = $this->generateMessageBlob( $module, $lang );
 186
 187                 try {
 188                         $newRow = array(
 189                                 'mr_resource' => $name,
 190                                 'mr_lang' => $lang,
 191                                 'mr_blob' => $newBlob,
 192                                 'mr_timestamp' => $dbw->timestamp()
 193                         );
 194
 195                         $dbw->replace( 'msg_resource',
 196                                 array( array( 'mr_resource', 'mr_lang' ) ),
 197                                 $newRow, __METHOD__
 198                         );
 199
 200                         // Figure out which messages were added and removed
 201                         $oldMessages = array_keys( FormatJson::decode( $oldBlob, true ) );
 202                         $newMessages = array_keys( FormatJson::decode( $newBlob, true ) );
 203                         $added = array_diff( $newMessages, $oldMessages );
 204                         $removed = array_diff( $oldMessages, $newMessages );
 205
 206                         // Delete removed messages, insert added ones
 207                         if ( $removed ) {
 208                                 $dbw->delete( 'msg_resource_links', array(
 209                                                 'mrl_resource' => $name,
 210                                                 'mrl_message' => $removed
 211                                         ), __METHOD__
 212                                 );
 213                         }
 214
 215                         $newLinksRows = array();
 216
 217                         foreach ( $added as $message ) {
 218                                 $newLinksRows[] = array(
 219                                         'mrl_resource' => $name,
 220                                         'mrl_message' => $message
 221                                 );
 222                         }
 223
 224                         if ( $newLinksRows ) {
 225                                 $dbw->insert( 'msg_resource_links', $newLinksRows, __METHOD__,
 226                                         array( 'IGNORE' ) // just in case
 227                                 );
 228                         }
 229                 } catch ( Exception $e ) {
 230                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 231                 }
 232                 return $newBlob;
 233         }
 234
 235         /**
 236          * Update a single message in all message blobs it occurs in.
 237          *
 238          * @param string $key Message key
 239          */
 240         public function updateMessage( $key ) {
 241                 try {
 242                         $dbw = wfGetDB( DB_MASTER );
 243
 244                         // Keep running until the updates queue is empty.
 245                         // Due to update conflicts, the queue might not be emptied
 246                         // in one iteration.
 247                         $updates = null;
 248                         do {
 249                                 $updates = $this->getUpdatesForMessage( $key, $updates );
 250
 251                                 foreach ( $updates as $k => $update ) {
 252                                         // Update the row on the condition that it
 253                                         // didn't change since we fetched it by putting
 254                                         // the timestamp in the WHERE clause.
 255                                         $success = $dbw->update( 'msg_resource',
 256                                                 array(
 257                                                         'mr_blob' => $update['newBlob'],
 258                                                         'mr_timestamp' => $dbw->timestamp() ),
 259                                                 array(
 260                                                         'mr_resource' => $update['resource'],
 261                                                         'mr_lang' => $update['lang'],
 262                                                         'mr_timestamp' => $update['timestamp'] ),
 263                                                 __METHOD__
 264                                         );
 265
 266                                         // Only requeue conflicted updates.
 267                                         // If update() returned false, don't retry, for
 268                                         // fear of getting into an infinite loop
 269                                         if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 270                                                 // Not conflicted
 271                                                 unset( $updates[$k] );
 272                                         }
 273                                 }
 274                         } while ( count( $updates ) );
 275
 276                         // No need to update msg_resource_links because we didn't add
 277                         // or remove any messages, we just changed their contents.
 278                 } catch ( Exception $e ) {
 279                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 280                 }
 281         }
 282
 283         public function clear() {
 284                 // TODO: Give this some more thought
 285                 try {
 286                         // Not using TRUNCATE, because that needs extra permissions,
 287                         // which maybe not granted to the database user.
 288                         $dbw = wfGetDB( DB_MASTER );
 289                         $dbw->delete( 'msg_resource', '*', __METHOD__ );
 290                         $dbw->delete( 'msg_resource_links', '*', __METHOD__ );
 291                 } catch ( Exception $e ) {
 292                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 293                 }
 294         }
 295
 296         /**
 297          * Create an update queue for updateMessage()
 298          *
 299          * @param string $key Message key
 300          * @param array $prevUpdates Updates queue to refresh or null to build a fresh update queue
 301          * @return array Updates queue
 302          */
 303         private function getUpdatesForMessage( $key, $prevUpdates = null ) {
 304                 $dbw = wfGetDB( DB_MASTER );
 305
 306                 if ( is_null( $prevUpdates ) ) {
 307                         // Fetch all blobs referencing $key
 308                         $res = $dbw->select(
 309                                 array( 'msg_resource', 'msg_resource_links' ),
 310                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 311                                 array( 'mrl_message' => $key, 'mr_resource=mrl_resource' ),
 312                                 __METHOD__
 313                         );
 314                 } else {
 315                         // Refetch the blobs referenced by $prevUpdates
 316
 317                         // Reorganize the (resource, lang) pairs in the format
 318                         // expected by makeWhereFrom2d()
 319                         $twoD = array();
 320
 321                         foreach ( $prevUpdates as $update ) {
 322                                 $twoD[$update['resource']][$update['lang']] = true;
 323                         }
 324
 325                         $res = $dbw->select( 'msg_resource',
 326                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 327                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 328                                 __METHOD__
 329                         );
 330                 }
 331
 332                 // Build the new updates queue
 333                 $updates = array();
 334
 335                 foreach ( $res as $row ) {
 336                         $updates[] = array(
 337                                 'resource' => $row->mr_resource,
 338                                 'lang' => $row->mr_lang,
 339                                 'timestamp' => $row->mr_timestamp,
 340                                 'newBlob' => $this->reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 341                         );
 342                 }
 343
 344                 return $updates;
 345         }
 346
 347         /**
 348          * Reencode a message blob with the updated value for a message
 349          *
 350          * @param string $blob Message blob (JSON object)
 351          * @param string $key Message key
 352          * @param string $lang Language code
 353          * @return string Message blob with $key replaced with its new value
 354          */
 355         private function reencodeBlob( $blob, $key, $lang ) {
 356                 $decoded = FormatJson::decode( $blob, true );
 357                 $decoded[$key] = wfMessage( $key )->inLanguage( $lang )->plain();
 358
 359                 return FormatJson::encode( (object)$decoded );
 360         }
 361
 362         /**
 363          * Get the message blobs for a set of modules from the database.
 364          * Modules whose blobs are not in the database are silently dropped.
 365          *
 366          * @param ResourceLoader $resourceLoader
 367          * @param array $modules Array of module names
 368          * @param string $lang Language code
 369          * @throws MWException
 370          * @return array Array mapping module names to blobs
 371          */
 372         private function getFromDB( ResourceLoader $resourceLoader, $modules, $lang ) {
 373                 if ( !count( $modules ) ) {
 374                         return array();
 375                 }
 376
 377                 $config = $resourceLoader->getConfig();
 378                 $retval = array();
 379                 $dbr = wfGetDB( DB_SLAVE );
 380                 $res = $dbr->select( 'msg_resource',
 381                         array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 382                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 383                         __METHOD__
 384                 );
 385
 386                 foreach ( $res as $row ) {
 387                         $module = $resourceLoader->getModule( $row->mr_resource );
 388                         if ( !$module ) {
 389                                 // This shouldn't be possible
 390                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 391                         }
 392
 393                         // Update the module's blobs if the set of messages changed or if the blob is
 394                         // older than the CacheEpoch setting
 395                         $keys = array_keys( FormatJson::decode( $row->mr_blob, true ) );
 396                         $values = array_values( array_unique( $module->getMessages() ) );
 397                         if ( $keys !== $values
 398                                 || wfTimestamp( TS_MW, $row->mr_timestamp ) <= $config->get( 'CacheEpoch' )
 399                         ) {
 400                                 $retval[$row->mr_resource] = $this->updateModule( $row->mr_resource, $module, $lang );
 401                         } else {
 402                                 $retval[$row->mr_resource] = $row->mr_blob;
 403                         }
 404                 }
 405
 406                 return $retval;
 407         }
 408
 409         /**
 410          * Generate the message blob for a given module in a given language.
 411          *
 412          * @param ResourceLoaderModule $module
 413          * @param string $lang Language code
 414          * @return string JSON object
 415          */
 416         private function generateMessageBlob( ResourceLoaderModule $module, $lang ) {
 417                 $messages = array();
 418
 419                 foreach ( $module->getMessages() as $key ) {
 420                         $messages[$key] = wfMessage( $key )->inLanguage( $lang )->plain();
 421                 }
 422
 423                 return FormatJson::encode( (object)$messages );
 424         }
 425 }