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                 return $blobs;
  55         }
  56
  57         /**
  58          * Generate and insert a new message blob. If the blob was already
  59          * present, it is not regenerated; instead, the preexisting blob
  60          * is fetched and returned.
  61          * @param $module string Module name
  62          * @param $lang string Language code
  63          * @return mixed Message blob or false if the module has no messages
  64          */
  65         public static function insertMessageBlob( $module, $lang ) {
  66                 $blob = self::generateMessageBlob( $module, $lang );
  67                 if ( !$blob ) {
  68                         return false;
  69                 }
  70
  71                 $dbw = wfGetDb( DB_MASTER );
  72                 $success = $dbw->insert( 'msg_resource', array(
  73                                 'mr_lang' => $lang,
  74                                 'mr_resource' => $module,
  75                                 'mr_blob' => $blob,
  76                                 'mr_timestamp' => $dbw->timestamp()
  77                         ),
  78                         __METHOD__,
  79                         array( 'IGNORE' )
  80                 );
  81                 if ( $success ) {
  82                         if ( $dbw->affectedRows() == 0 ) {
  83                                 // Blob was already present, fetch it
  84                                 $blob = $dbr->selectField( 'msg_resource', 'mr_blob', array(
  85                                                 'mr_resource' => $module,
  86                                                 'mr_lang' => $lang,
  87                                         ),
  88                                         __METHOD__
  89                                 );
  90                         } else {
  91                                 // Update msg_resource_links
  92                                 $rows = array();
  93                                 $mod = ResourceLoader::getModule( $module );
  94                                 foreach ( $mod->getMessages() as $key ) {
  95                                         $rows[] = array(
  96                                                 'mrl_resource' => $module,
  97                                                 'mrl_message' => $key
  98                                         );
  99                                 }
 100                                 $dbw->insert( 'msg_resource_links', $rows,
 101                                         __METHOD__, array( 'IGNORE' )
 102                                 );
 103                         }
 104                 }
 105                 return $blob;
 106         }
 107
 108         /**
 109          * Update all message blobs for a given module.
 110          * @param $module string Module name
 111          * @param $lang string Language code (optional)
 112          * @return mixed If $lang is set, the new message blob for that language is returned if present. Otherwise, null is returned.
 113          */
 114         public static function updateModule( $module, $lang = null ) {
 115                 $retval = null;
 116
 117                 // Find all existing blobs for this module
 118                 $dbw = wfGetDb( DB_MASTER );
 119                 $res = $dbw->select( 'msg_resource', array( 'mr_lang', 'mr_blob' ),
 120                         array( 'mr_resource' => $module ),
 121                         __METHOD__
 122                 );
 123
 124                 // Build the new msg_resource rows
 125                 $newRows = array();
 126                 $now = $dbw->timestamp();
 127                 // Save the last-processed old and new blobs for later
 128                 $oldBlob = $newBlob = null;
 129                 foreach ( $res as $row ) {
 130                         $oldBlob = $row->mr_blob;
 131                         $newBlob = self::generateMessageBlob( $module, $row->mr_lang );
 132                         if ( $row->mr_lang === $lang ) {
 133                                 $retval = $newBlob;
 134                         }
 135                         $newRows[] = array(
 136                                 'mr_resource' => $module,
 137                                 'mr_lang' => $row->mr_lang,
 138                                 'mr_blob' => $newBlob,
 139                                 'mr_timestamp' => $now
 140                         );
 141                 }
 142
 143                 $dbw->replace( 'msg_resource',
 144                         array( array( 'mr_resource', 'mr_lang' ) ),
 145                         $newRows, __METHOD__
 146                 );
 147
 148                 // Figure out which messages were added and removed
 149                 $oldMessages = array_keys( FormatJson::decode( $oldBlob, true ) );
 150                 $newMessages = array_keys( FormatJson::decode( $newBlob, true ) );
 151                 $added = array_diff( $newMessages, $oldMessages );
 152                 $removed = array_diff( $oldMessages, $newMessages );
 153
 154                 // Delete removed messages, insert added ones
 155                 if ( $removed ) {
 156                         $dbw->delete( 'msg_resource_links', array(
 157                                         'mrl_resource' => $module,
 158                                         'mrl_message' => $removed
 159                                 ), __METHOD__
 160                         );
 161                 }
 162                 $newLinksRows = array();
 163                 foreach ( $added as $message ) {
 164                         $newLinksRows[] = array(
 165                                 'mrl_resource' => $module,
 166                                 'mrl_message' => $message
 167                         );
 168                 }
 169                 if ( $newLinksRows ) {
 170                         $dbw->insert( 'msg_resource_links', $newLinksRows, __METHOD__,
 171                                  array( 'IGNORE' ) // just in case
 172                         );
 173                 }
 174
 175                 return $retval;
 176         }
 177
 178         /**
 179          * Update a single message in all message blobs it occurs in.
 180          * @param $key string Message key
 181          */
 182         public static function updateMessage( $key ) {
 183                 $dbw = wfGetDb( DB_MASTER );
 184
 185                 // Keep running until the updates queue is empty.
 186                 // Due to update conflicts, the queue might not be emptied
 187                 // in one iteration.
 188                 $updates = null;
 189                 do {
 190                         $updates = self::getUpdatesForMessage( $key, $updates );
 191                         foreach ( $updates as $key => $update ) {
 192                                 // Update the row on the condition that it
 193                                 // didn't change since we fetched it by putting
 194                                 // the timestamp in the WHERE clause.
 195                                 $success = $dbw->update( 'msg_resource',
 196                                         array(  'mr_blob' => $update['newBlob'],
 197                                                 'mr_timestamp' => $dbw->timestamp() ),
 198                                         array(  'mr_resource' => $update['resource'],
 199                                                 'mr_lang' => $update['lang'],
 200                                                 'mr_timestamp' => $update['timestamp'] ),
 201                                         __METHOD__
 202                                 );
 203
 204                                 // Only requeue conflicted updates.
 205                                 // If update() returned false, don't retry, for
 206                                 // fear of getting into an infinite loop
 207                                 if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 208                                         // Not conflicted
 209                                         unset( $updates[$key] );
 210                                 }
 211                         }
 212                 } while ( count( $updates ) );
 213
 214                 // No need to update msg_resource_links because we didn't add
 215                 // or remove any messages, we just changed their contents.
 216         }
 217
 218         public static function clear() {
 219                 // TODO: Give this some more thought
 220                 // TODO: Is TRUNCATE better?
 221                 $dbw = wfGetDb( DB_MASTER );
 222                 $dbw->delete( 'msg_resource', '*', __METHOD__ );
 223                 $dbw->delete( 'msg_resource_links', '*', __METHOD__ );
 224         }
 225
 226         /**
 227          * Create an update queue for updateMessage()
 228          * @param $key string Message key
 229          * @param $prevUpdates array Updates queue to refresh or null to build a fresh update queue
 230          * @return array Updates queue
 231          */
 232         private static function getUpdatesForMessage( $key, $prevUpdates = null ) {
 233                 $dbw = wfGetDb( DB_MASTER );
 234                 if ( is_null( $prevUpdates ) ) {
 235                         // Fetch all blobs referencing $key
 236                         $res = $dbw->select(
 237                                 array(  'msg_resource', 'msg_resource_links' ),
 238                                 array(  'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 239                                 array(  'mrl_message' => $key, 'mr_resource=mrl_resource' ),
 240                                 __METHOD__
 241                         );
 242                 } else {
 243                         // Refetch the blobs referenced by $prevUpdates
 244
 245                         // Reorganize the (resource, lang) pairs in the format
 246                         // expected by makeWhereFrom2d()
 247                         $twoD = array();
 248                         foreach ( $prevUpdates as $update ) {
 249                                 $twoD[$update['resource']][$update['lang']] = true;
 250                         }
 251
 252                         $res = $dbw->select( 'msg_resource',
 253                                 array(  'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 254                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 255                                 __METHOD__
 256                         );
 257                 }
 258
 259                 // Build the new updates queue
 260                 $updates = array();
 261                 foreach ( $res as $row ) {
 262                         $updates[] = array(
 263                                 'resource' => $row->mr_resource,
 264                                 'lang' => $row->mr_lang,
 265                                 'timestamp' => $row->mr_timestamp,
 266                                 'newBlob' => self::reencodeBlob( $row->mr_blob,
 267                                         $key, $row->mr_lang )
 268                         );
 269                 }
 270                 return $updates;
 271         }
 272
 273         /**
 274          * Reencode a message blob with the updated value for a message
 275          * @param $blob string Message blob (JSON object)
 276          * @param $key string Message key
 277          * @param $lang string Language code
 278          * @return Message blob with $key replaced with its new value
 279          */
 280         private static function reencodeBlob( $blob, $key, $lang ) {
 281                 $decoded = FormatJson::decode( $blob, true );
 282                 $decoded[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 283                 return FormatJson::encode( $decoded );
 284         }
 285
 286         /**
 287          * Get the message blobs for a set of modules from the database.
 288          * Modules whose blobs are not in the database are silently dropped.
 289          * @param $modules array Array of module names
 290          * @param $lang string Language code
 291          * @return array Array mapping module names to blobs
 292          */
 293         private static function getFromDB( $modules, $lang ) {
 294                 $retval = array();
 295                 $dbr = wfGetDB( DB_SLAVE );
 296                 $res = $dbr->select( 'msg_resource', array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 297                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 298                         __METHOD__
 299                 );
 300                 foreach ( $res as $row ) {
 301                         $module = ResourceLoader::getModule( $row->mr_resource );
 302                         if ( !$module ) {
 303                                 // This shouldn't be possible
 304                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 305                         }
 306                         if ( array_keys( FormatJson::decode( $row->mr_blob, true ) ) !== $module->getMessages() ) {
 307                                 $retval[$row->mr_resource] = self::updateModule( $row->mr_resource, $lang );
 308                         } else {
 309                                 $retval[$row->mr_resource] = $row->mr_blob;
 310                         }
 311                 }
 312                 return $retval;
 313         }
 314
 315         /**
 316          * Generate the message blob for a given module in a given language.
 317          * @param $module string Module name
 318          * @param $lang string Language code
 319          * @return string JSON object
 320          */
 321         private static function generateMessageBlob( $module, $lang ) {
 322                 $mod = ResourceLoader::getModule( $module );
 323                 $messages = array();
 324                 foreach ( $mod->getMessages() as $key ) {
 325                         $messages[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 326                 }
 327                 return FormatJson::encode( $messages );
 328         }
 329 }