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 objects keyed by module name
  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( array_keys( $modules ), $lang );
  47
  48                 // Generate blobs for any missing modules and store them in the DB
  49                 $missing = array_diff( array_keys( $modules ), array_keys( $blobs ) );
  50                 foreach ( $missing as $name ) {
  51                         $blob = self::insertMessageBlob( $name, $modules[$name], $lang );
  52                         if ( $blob ) {
  53                                 $blobs[$name] = $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( $name, ResourceLoaderModule $module, $lang ) {
  70                 $blob = self::generateMessageBlob( $name, $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' => $name,
  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' => $name,
  92                                                 'mr_lang' => $lang,
  93                                         ),
  94                                         __METHOD__
  95                                 );
  96                         } else {
  97                                 // Update msg_resource_links
  98                                 $rows = array();
  99
 100                                 foreach ( $module->getMessages() as $key ) {
 101                                         $rows[] = array(
 102                                                 'mrl_resource' => $name,
 103                                                 'mrl_message' => $key
 104                                         );
 105                                 }
 106                                 $dbw->insert( 'msg_resource_links', $rows,
 107                                         __METHOD__, array( 'IGNORE' )
 108                                 );
 109                         }
 110                 }
 111
 112                 return $blob;
 113         }
 114
 115         /**
 116          * Update all message blobs for a given module.
 117          * @param $module string Module name
 118          * @param $lang string Language code (optional)
 119          * @return mixed If $lang is set, the new message blob for that language is
 120          *    returned if present. Otherwise, null is returned.
 121          */
 122         public static function updateModule( $name, ResourceLoaderModule $module, $lang = null ) {
 123                 $retval = null;
 124
 125                 // Find all existing blobs for this module
 126                 $dbw = wfGetDB( DB_MASTER );
 127                 $res = $dbw->select( 'msg_resource',
 128                         array( 'mr_lang', 'mr_blob' ),
 129                         array( 'mr_resource' => $name ),
 130                         __METHOD__
 131                 );
 132
 133                 // Build the new msg_resource rows
 134                 $newRows = array();
 135                 $now = $dbw->timestamp();
 136                 // Save the last-processed old and new blobs for later
 137                 $oldBlob = $newBlob = null;
 138
 139                 foreach ( $res as $row ) {
 140                         $oldBlob = $row->mr_blob;
 141                         $newBlob = self::generateMessageBlob( $name, $module, $row->mr_lang );
 142
 143                         if ( $row->mr_lang === $lang ) {
 144                                 $retval = $newBlob;
 145                         }
 146                         $newRows[] = array(
 147                                 'mr_resource' => $name,
 148                                 'mr_lang' => $row->mr_lang,
 149                                 'mr_blob' => $newBlob,
 150                                 'mr_timestamp' => $now
 151                         );
 152                 }
 153
 154                 $dbw->replace( 'msg_resource',
 155                         array( array( 'mr_resource', 'mr_lang' ) ),
 156                         $newRows, __METHOD__
 157                 );
 158
 159                 // Figure out which messages were added and removed
 160                 $oldMessages = array_keys( FormatJson::decode( $oldBlob, true ) );
 161                 $newMessages = array_keys( FormatJson::decode( $newBlob, true ) );
 162                 $added = array_diff( $newMessages, $oldMessages );
 163                 $removed = array_diff( $oldMessages, $newMessages );
 164
 165                 // Delete removed messages, insert added ones
 166                 if ( $removed ) {
 167                         $dbw->delete( 'msg_resource_links', array(
 168                                         'mrl_resource' => $name,
 169                                         'mrl_message' => $removed
 170                                 ), __METHOD__
 171                         );
 172                 }
 173
 174                 $newLinksRows = array();
 175
 176                 foreach ( $added as $message ) {
 177                         $newLinksRows[] = array(
 178                                 'mrl_resource' => $name,
 179                                 'mrl_message' => $message
 180                         );
 181                 }
 182
 183                 if ( $newLinksRows ) {
 184                         $dbw->insert( 'msg_resource_links', $newLinksRows, __METHOD__,
 185                                  array( 'IGNORE' ) // just in case
 186                         );
 187                 }
 188
 189                 return $retval;
 190         }
 191
 192         /**
 193          * Update a single message in all message blobs it occurs in.
 194          * @param $key string Message key
 195          */
 196         public static function updateMessage( $key ) {
 197                 $dbw = wfGetDB( DB_MASTER );
 198
 199                 // Keep running until the updates queue is empty.
 200                 // Due to update conflicts, the queue might not be emptied
 201                 // in one iteration.
 202                 $updates = null;
 203                 do {
 204                         $updates = self::getUpdatesForMessage( $key, $updates );
 205
 206                         foreach ( $updates as $key => $update ) {
 207                                 // Update the row on the condition that it
 208                                 // didn't change since we fetched it by putting
 209                                 // the timestamp in the WHERE clause.
 210                                 $success = $dbw->update( 'msg_resource',
 211                                         array(
 212                                                 'mr_blob' => $update['newBlob'],
 213                                                 'mr_timestamp' => $dbw->timestamp() ),
 214                                         array(
 215                                                 'mr_resource' => $update['resource'],
 216                                                 'mr_lang' => $update['lang'],
 217                                                 'mr_timestamp' => $update['timestamp'] ),
 218                                         __METHOD__
 219                                 );
 220
 221                                 // Only requeue conflicted updates.
 222                                 // If update() returned false, don't retry, for
 223                                 // fear of getting into an infinite loop
 224                                 if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 225                                         // Not conflicted
 226                                         unset( $updates[$key] );
 227                                 }
 228                         }
 229                 } while ( count( $updates ) );
 230
 231                 // No need to update msg_resource_links because we didn't add
 232                 // or remove any messages, we just changed their contents.
 233         }
 234
 235         public static function clear() {
 236                 // TODO: Give this some more thought
 237                 // TODO: Is TRUNCATE better?
 238                 $dbw = wfGetDB( DB_MASTER );
 239                 $dbw->delete( 'msg_resource', '*', __METHOD__ );
 240                 $dbw->delete( 'msg_resource_links', '*', __METHOD__ );
 241         }
 242
 243         /**
 244          * Create an update queue for updateMessage()
 245          * @param $key string Message key
 246          * @param $prevUpdates array Updates queue to refresh or null to build a fresh update queue
 247          * @return array Updates queue
 248          */
 249         private static function getUpdatesForMessage( $key, $prevUpdates = null ) {
 250                 $dbw = wfGetDB( DB_MASTER );
 251
 252                 if ( is_null( $prevUpdates ) ) {
 253                         // Fetch all blobs referencing $key
 254                         $res = $dbw->select(
 255                                 array( 'msg_resource', 'msg_resource_links' ),
 256                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 257                                 array( 'mrl_message' => $key, 'mr_resource=mrl_resource' ),
 258                                 __METHOD__
 259                         );
 260                 } else {
 261                         // Refetch the blobs referenced by $prevUpdates
 262
 263                         // Reorganize the (resource, lang) pairs in the format
 264                         // expected by makeWhereFrom2d()
 265                         $twoD = array();
 266
 267                         foreach ( $prevUpdates as $update ) {
 268                                 $twoD[$update['resource']][$update['lang']] = true;
 269                         }
 270
 271                         $res = $dbw->select( 'msg_resource',
 272                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 273                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 274                                 __METHOD__
 275                         );
 276                 }
 277
 278                 // Build the new updates queue
 279                 $updates = array();
 280
 281                 foreach ( $res as $row ) {
 282                         $updates[] = array(
 283                                 'resource' => $row->mr_resource,
 284                                 'lang' => $row->mr_lang,
 285                                 'timestamp' => $row->mr_timestamp,
 286                                 'newBlob' => self::reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 287                         );
 288                 }
 289
 290                 return $updates;
 291         }
 292
 293         /**
 294          * Reencode a message blob with the updated value for a message
 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] = wfMsgExt( $key, array( 'language' => $lang ) );
 303
 304                 return FormatJson::encode( $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          * @param $modules array Array of module names
 311          * @param $lang string Language code
 312          * @return array Array mapping module names to blobs
 313          */
 314         private static function getFromDB( $modules, $lang ) {
 315                 $retval = array();
 316                 $dbr = wfGetDB( DB_SLAVE );
 317                 $res = $dbr->select( 'msg_resource',
 318                         array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 319                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 320                         __METHOD__
 321                 );
 322
 323                 foreach ( $res as $row ) {
 324                         $module = ResourceLoader::getModule( $row->mr_resource );
 325                         if ( !$module ) {
 326                                 // This shouldn't be possible
 327                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 328                         }
 329                         if ( array_keys( FormatJson::decode( $row->mr_blob, true ) ) !== $module->getMessages() ) {
 330                                 $retval[$row->mr_resource] = self::updateModule( $row->mr_resource, $lang );
 331                         } else {
 332                                 $retval[$row->mr_resource] = $row->mr_blob;
 333                         }
 334                 }
 335
 336                 return $retval;
 337         }
 338
 339         /**
 340          * Generate the message blob for a given module in a given language.
 341          * @param $module string Module name
 342          * @param $lang string Language code
 343          * @return string JSON object
 344          */
 345         private static function generateMessageBlob( $name, ResourceLoaderModule $module, $lang ) {
 346                 $messages = array();
 347
 348                 foreach ( $module->getMessages() as $key ) {
 349                         $messages[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 350                 }
 351
 352                 return FormatJson::encode( $messages );
 353         }
 354 }