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