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