includes/MessageBlobStore.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @author Roan Kattouw
  19  * @author Trevor Parscal
  20  */
  21
  22 /**
  23  * This class provides access to the resource message blobs storage used by
  24  * the ResourceLoader.
  25  *
  26  * A message blob is a JSON object containing the interface messages for a
  27  * certain resource in a certain language. These message blobs are cached
  28  * in the msg_resource table and automatically invalidated when one of their
  29  * consistuent messages or the resource itself is changed.
  30  */
  31 class MessageBlobStore {
  32         /**
  33          * Get the message blobs for a set of modules
  34          * @param $modules array Array of module names
  35          * @param $lang string Language code
  36          * @return array An array mapping module names to message blobs
  37          */
  38         public static function get( $modules, $lang ) {
  39                 // TODO: Invalidate blob when module touched
  40                 wfProfileIn( __METHOD__ );
  41                 if ( !count( $modules ) ) {
  42                         wfProfileOut( __METHOD__ );
  43                         return array();
  44                 }
  45                 // Try getting from the DB first
  46                 $blobs = self::getFromDB( $modules, $lang );
  47
  48                 // Generate blobs for any missing modules and store them in the DB
  49                 $missing = array_diff( $modules, array_keys( $blobs ) );
  50                 foreach ( $missing as $module ) {
  51                         $blob = self::insertMessageBlob( $module, $lang );
  52                         if ( $blob ) {
  53                                 $blobs[$module] = $blob;
  54                         }
  55                 }
  56
  57                 wfProfileOut( __METHOD__ );
  58                 return $blobs;
  59         }
  60
  61         /**
  62          * Generate and insert a new message blob. If the blob was already
  63          * present, it is not regenerated; instead, the preexisting blob
  64          * is fetched and returned.
  65          * @param $module string Module name
  66          * @param $lang string Language code
  67          * @return mixed Message blob or false if the module has no messages
  68          */
  69         public static function insertMessageBlob( $module, $lang ) {
  70                 $blob = self::generateMessageBlob( $module, $lang );
  71
  72                 if ( !$blob ) {
  73                         return false;
  74                 }
  75
  76                 $dbw = wfGetDB( DB_MASTER );
  77                 $success = $dbw->insert( 'msg_resource', array(
  78                                 'mr_lang' => $lang,
  79                                 'mr_resource' => $module,
  80                                 'mr_blob' => $blob,
  81                                 'mr_timestamp' => $dbw->timestamp()
  82                         ),
  83                         __METHOD__,
  84                         array( 'IGNORE' )
  85                 );
  86
  87                 if ( $success ) {
  88                         if ( $dbw->affectedRows() == 0 ) {
  89                                 // Blob was already present, fetch it
  90                                 $blob = $dbw->selectField( 'msg_resource', 'mr_blob', array(
  91                                                 'mr_resource' => $module,
  92                                                 'mr_lang' => $lang,
  93                                         ),
  94                                         __METHOD__
  95                                 );
  96                         } else {
  97                                 // Update msg_resource_links
  98                                 $rows = array();
  99                                 $mod = ResourceLoader::getModule( $module );
 100
 101                                 foreach ( $mod->getMessages() as $key ) {
 102                                         $rows[] = array(
 103                                                 'mrl_resource' => $module,
 104                                                 'mrl_message' => $key
 105                                         );
 106                                 }
 107                                 $dbw->insert( 'msg_resource_links', $rows,
 108                                         __METHOD__, array( 'IGNORE' )
 109                                 );
 110                         }
 111                 }
 112
 113                 return $blob;
 114         }
 115
 116         /**
 117          * Update all message blobs for a given module.
 118          * @param $module string Module name
 119          * @param $lang string Language code (optional)
 120          * @return mixed If $lang is set, the new message blob for that language is
 121          *    returned if present. Otherwise, null is returned.
 122          */
 123         public static function updateModule( $module, $lang = null ) {
 124                 $retval = null;
 125
 126                 // Find all existing blobs for this module
 127                 $dbw = wfGetDB( DB_MASTER );
 128                 $res = $dbw->select( 'msg_resource',
 129                         array( 'mr_lang', 'mr_blob' ),
 130                         array( 'mr_resource' => $module ),
 131                         __METHOD__
 132                 );
 133
 134                 // Build the new msg_resource rows
 135                 $newRows = array();
 136                 $now = $dbw->timestamp();
 137                 // Save the last-processed old and new blobs for later
 138                 $oldBlob = $newBlob = null;
 139
 140                 foreach ( $res as $row ) {
 141                         $oldBlob = $row->mr_blob;
 142                         $newBlob = self::generateMessageBlob( $module, $row->mr_lang );
 143
 144                         if ( $row->mr_lang === $lang ) {
 145                                 $retval = $newBlob;
 146                         }
 147                         $newRows[] = array(
 148                                 'mr_resource' => $module,
 149                                 'mr_lang' => $row->mr_lang,
 150                                 'mr_blob' => $newBlob,
 151                                 'mr_timestamp' => $now
 152                         );
 153                 }
 154
 155                 $dbw->replace( 'msg_resource',
 156                         array( array( 'mr_resource', 'mr_lang' ) ),
 157                         $newRows, __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' => $module,
 170                                         'mrl_message' => $removed
 171                                 ), __METHOD__
 172                         );
 173                 }
 174
 175                 $newLinksRows = array();
 176
 177                 foreach ( $added as $message ) {
 178                         $newLinksRows[] = array(
 179                                 'mrl_resource' => $module,
 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
 190                 return $retval;
 191         }
 192
 193         /**
 194          * Update a single message in all message blobs it occurs in.
 195          * @param $key string Message key
 196          */
 197         public static function updateMessage( $key ) {
 198                 $dbw = wfGetDB( DB_MASTER );
 199
 200                 // Keep running until the updates queue is empty.
 201                 // Due to update conflicts, the queue might not be emptied
 202                 // in one iteration.
 203                 $updates = null;
 204                 do {
 205                         $updates = self::getUpdatesForMessage( $key, $updates );
 206
 207                         foreach ( $updates as $key => $update ) {
 208                                 // Update the row on the condition that it
 209                                 // didn't change since we fetched it by putting
 210                                 // the timestamp in the WHERE clause.
 211                                 $success = $dbw->update( 'msg_resource',
 212                                         array(
 213                                                 'mr_blob' => $update['newBlob'],
 214                                                 'mr_timestamp' => $dbw->timestamp() ),
 215                                         array(
 216                                                 'mr_resource' => $update['resource'],
 217                                                 'mr_lang' => $update['lang'],
 218                                                 'mr_timestamp' => $update['timestamp'] ),
 219                                         __METHOD__
 220                                 );
 221
 222                                 // Only requeue conflicted updates.
 223                                 // If update() returned false, don't retry, for
 224                                 // fear of getting into an infinite loop
 225                                 if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 226                                         // Not conflicted
 227                                         unset( $updates[$key] );
 228                                 }
 229                         }
 230                 } while ( count( $updates ) );
 231
 232                 // No need to update msg_resource_links because we didn't add
 233                 // or remove any messages, we just changed their contents.
 234         }
 235
 236         public static function clear() {
 237                 // TODO: Give this some more thought
 238                 // TODO: Is TRUNCATE better?
 239                 $dbw = wfGetDB( DB_MASTER );
 240                 $dbw->delete( 'msg_resource', '*', __METHOD__ );
 241                 $dbw->delete( 'msg_resource_links', '*', __METHOD__ );
 242         }
 243
 244         /**
 245          * Create an update queue for updateMessage()
 246          * @param $key string Message key
 247          * @param $prevUpdates array Updates queue to refresh or null to build a fresh update queue
 248          * @return array Updates queue
 249          */
 250         private static function getUpdatesForMessage( $key, $prevUpdates = null ) {
 251                 $dbw = wfGetDB( DB_MASTER );
 252
 253                 if ( is_null( $prevUpdates ) ) {
 254                         // Fetch all blobs referencing $key
 255                         $res = $dbw->select(
 256                                 array( 'msg_resource', 'msg_resource_links' ),
 257                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 258                                 array( 'mrl_message' => $key, 'mr_resource=mrl_resource' ),
 259                                 __METHOD__
 260                         );
 261                 } else {
 262                         // Refetch the blobs referenced by $prevUpdates
 263
 264                         // Reorganize the (resource, lang) pairs in the format
 265                         // expected by makeWhereFrom2d()
 266                         $twoD = array();
 267
 268                         foreach ( $prevUpdates as $update ) {
 269                                 $twoD[$update['resource']][$update['lang']] = true;
 270                         }
 271
 272                         $res = $dbw->select( 'msg_resource',
 273                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 274                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 275                                 __METHOD__
 276                         );
 277                 }
 278
 279                 // Build the new updates queue
 280                 $updates = array();
 281
 282                 foreach ( $res as $row ) {
 283                         $updates[] = array(
 284                                 'resource' => $row->mr_resource,
 285                                 'lang' => $row->mr_lang,
 286                                 'timestamp' => $row->mr_timestamp,
 287                                 'newBlob' => self::reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 288                         );
 289                 }
 290
 291                 return $updates;
 292         }
 293
 294         /**
 295          * Reencode a message blob with the updated value for a message
 296          * @param $blob string Message blob (JSON object)
 297          * @param $key string Message key
 298          * @param $lang string Language code
 299          * @return Message blob with $key replaced with its new value
 300          */
 301         private static function reencodeBlob( $blob, $key, $lang ) {
 302                 $decoded = FormatJson::decode( $blob, true );
 303                 $decoded[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 304
 305                 return FormatJson::encode( $decoded );
 306         }
 307
 308         /**
 309          * Get the message blobs for a set of modules from the database.
 310          * Modules whose blobs are not in the database are silently dropped.
 311          * @param $modules array Array of module names
 312          * @param $lang string Language code
 313          * @return array Array mapping module names to blobs
 314          */
 315         private static function getFromDB( $modules, $lang ) {
 316                 $retval = array();
 317                 $dbr = wfGetDB( DB_SLAVE );
 318                 $res = $dbr->select( 'msg_resource',
 319                         array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 320                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 321                         __METHOD__
 322                 );
 323
 324                 foreach ( $res as $row ) {
 325                         $module = ResourceLoader::getModule( $row->mr_resource );
 326                         if ( !$module ) {
 327                                 // This shouldn't be possible
 328                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 329                         }
 330                         if ( array_keys( FormatJson::decode( $row->mr_blob, true ) ) !== $module->getMessages() ) {
 331                                 $retval[$row->mr_resource] = self::updateModule( $row->mr_resource, $lang );
 332                         } else {
 333                                 $retval[$row->mr_resource] = $row->mr_blob;
 334                         }
 335                 }
 336
 337                 return $retval;
 338         }
 339
 340         /**
 341          * Generate the message blob for a given module in a given language.
 342          * @param $module string Module name
 343          * @param $lang string Language code
 344          * @return string JSON object
 345          */
 346         private static function generateMessageBlob( $module, $lang ) {
 347                 $mod = ResourceLoader::getModule( $module );
 348                 $messages = array();
 349
 350                 foreach ( $mod->getMessages() as $key ) {
 351                         $messages[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 352                 }
 353
 354                 return FormatJson::encode( $messages );
 355         }
 356 }