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