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',
 126                         array( 'mr_lang', 'mr_blob' ),
 127                         array( 'mr_resource' => $module ),
 128                         __METHOD__
 129                 );
 130
 131                 // Build the new msg_resource rows
 132                 $newRows = array();
 133                 $now = $dbw->timestamp();
 134                 // Save the last-processed old and new blobs for later
 135                 $oldBlob = $newBlob = null;
 136
 137                 foreach ( $res as $row ) {
 138                         $oldBlob = $row->mr_blob;
 139                         $newBlob = self::generateMessageBlob( $module, $row->mr_lang );
 140
 141                         if ( $row->mr_lang === $lang ) {
 142                                 $retval = $newBlob;
 143                         }
 144                         $newRows[] = array(
 145                                 'mr_resource' => $module,
 146                                 'mr_lang' => $row->mr_lang,
 147                                 'mr_blob' => $newBlob,
 148                                 'mr_timestamp' => $now
 149                         );
 150                 }
 151
 152                 $dbw->replace( 'msg_resource',
 153                         array( array( 'mr_resource', 'mr_lang' ) ),
 154                         $newRows, __METHOD__
 155                 );
 156
 157                 // Figure out which messages were added and removed
 158                 $oldMessages = array_keys( FormatJson::decode( $oldBlob, true ) );
 159                 $newMessages = array_keys( FormatJson::decode( $newBlob, true ) );
 160                 $added = array_diff( $newMessages, $oldMessages );
 161                 $removed = array_diff( $oldMessages, $newMessages );
 162
 163                 // Delete removed messages, insert added ones
 164                 if ( $removed ) {
 165                         $dbw->delete( 'msg_resource_links', array(
 166                                         'mrl_resource' => $module,
 167                                         'mrl_message' => $removed
 168                                 ), __METHOD__
 169                         );
 170                 }
 171
 172                 $newLinksRows = array();
 173
 174                 foreach ( $added as $message ) {
 175                         $newLinksRows[] = array(
 176                                 'mrl_resource' => $module,
 177                                 'mrl_message' => $message
 178                         );
 179                 }
 180
 181                 if ( $newLinksRows ) {
 182                         $dbw->insert( 'msg_resource_links', $newLinksRows, __METHOD__,
 183                                  array( 'IGNORE' ) // just in case
 184                         );
 185                 }
 186
 187                 return $retval;
 188         }
 189
 190         /**
 191          * Update a single message in all message blobs it occurs in.
 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 $key => $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( $updates[$key] );
 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          * @param $key string Message key
 244          * @param $prevUpdates array Updates queue to refresh or null to build a fresh update queue
 245          * @return array Updates queue
 246          */
 247         private static function getUpdatesForMessage( $key, $prevUpdates = null ) {
 248                 $dbw = wfGetDB( DB_MASTER );
 249
 250                 if ( is_null( $prevUpdates ) ) {
 251                         // Fetch all blobs referencing $key
 252                         $res = $dbw->select(
 253                                 array( 'msg_resource', 'msg_resource_links' ),
 254                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 255                                 array( 'mrl_message' => $key, 'mr_resource=mrl_resource' ),
 256                                 __METHOD__
 257                         );
 258                 } else {
 259                         // Refetch the blobs referenced by $prevUpdates
 260
 261                         // Reorganize the (resource, lang) pairs in the format
 262                         // expected by makeWhereFrom2d()
 263                         $twoD = array();
 264
 265                         foreach ( $prevUpdates as $update ) {
 266                                 $twoD[$update['resource']][$update['lang']] = true;
 267                         }
 268
 269                         $res = $dbw->select( 'msg_resource',
 270                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 271                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 272                                 __METHOD__
 273                         );
 274                 }
 275
 276                 // Build the new updates queue
 277                 $updates = array();
 278
 279                 foreach ( $res as $row ) {
 280                         $updates[] = array(
 281                                 'resource' => $row->mr_resource,
 282                                 'lang' => $row->mr_lang,
 283                                 'timestamp' => $row->mr_timestamp,
 284                                 'newBlob' => self::reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 285                         );
 286                 }
 287
 288                 return $updates;
 289         }
 290
 291         /**
 292          * Reencode a message blob with the updated value for a message
 293          * @param $blob string Message blob (JSON object)
 294          * @param $key string Message key
 295          * @param $lang string Language code
 296          * @return Message blob with $key replaced with its new value
 297          */
 298         private static function reencodeBlob( $blob, $key, $lang ) {
 299                 $decoded = FormatJson::decode( $blob, true );
 300                 $decoded[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 301
 302                 return FormatJson::encode( $decoded );
 303         }
 304
 305         /**
 306          * Get the message blobs for a set of modules from the database.
 307          * Modules whose blobs are not in the database are silently dropped.
 308          * @param $modules array Array of module names
 309          * @param $lang string Language code
 310          * @return array Array mapping module names to blobs
 311          */
 312         private static function getFromDB( $modules, $lang ) {
 313                 $retval = array();
 314                 $dbr = wfGetDB( DB_SLAVE );
 315                 $res = $dbr->select( 'msg_resource',
 316                         array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 317                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 318                         __METHOD__
 319                 );
 320
 321                 foreach ( $res as $row ) {
 322                         $module = ResourceLoader::getModule( $row->mr_resource );
 323                         if ( !$module ) {
 324                                 // This shouldn't be possible
 325                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 326                         }
 327                         if ( array_keys( FormatJson::decode( $row->mr_blob, true ) ) !== $module->getMessages() ) {
 328                                 $retval[$row->mr_resource] = self::updateModule( $row->mr_resource, $lang );
 329                         } else {
 330                                 $retval[$row->mr_resource] = $row->mr_blob;
 331                         }
 332                 }
 333
 334                 return $retval;
 335         }
 336
 337         /**
 338          * Generate the message blob for a given module in a given language.
 339          * @param $module string Module name
 340          * @param $lang string Language code
 341          * @return string JSON object
 342          */
 343         private static function generateMessageBlob( $module, $lang ) {
 344                 $mod = ResourceLoader::getModule( $module );
 345                 $messages = array();
 346
 347                 foreach ( $mod->getMessages() as $key ) {
 348                         $messages[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 349                 }
 350
 351                 return FormatJson::encode( $messages );
 352         }
 353 }