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