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         /**
  34          * Get the message blobs for a set of modules
  35          *
  36          * @param $resourceLoader ResourceLoader object
  37          * @param $modules array Array of module objects keyed by module name
  38          * @param $lang string Language code
  39          * @return array An array mapping module names to message blobs
  40          */
  41         public static function get( ResourceLoader $resourceLoader, $modules, $lang ) {
  42                 wfProfileIn( __METHOD__ );
  43                 if ( !count( $modules ) ) {
  44                         wfProfileOut( __METHOD__ );
  45                         return array();
  46                 }
  47                 // Try getting from the DB first
  48                 $blobs = self::getFromDB( $resourceLoader, array_keys( $modules ), $lang );
  49
  50                 // Generate blobs for any missing modules and store them in the DB
  51                 $missing = array_diff( array_keys( $modules ), array_keys( $blobs ) );
  52                 foreach ( $missing as $name ) {
  53                         $blob = self::insertMessageBlob( $name, $modules[$name], $lang );
  54                         if ( $blob ) {
  55                                 $blobs[$name] = $blob;
  56                         }
  57                 }
  58
  59                 wfProfileOut( __METHOD__ );
  60                 return $blobs;
  61         }
  62
  63         /**
  64          * Generate and insert a new message blob. If the blob was already
  65          * present, it is not regenerated; instead, the preexisting blob
  66          * is fetched and returned.
  67          *
  68          * @param $name String: module name
  69          * @param $module ResourceLoaderModule object
  70          * @param $lang String: language code
  71          * @return mixed Message blob or false if the module has no messages
  72          */
  73         public static function insertMessageBlob( $name, ResourceLoaderModule $module, $lang ) {
  74                 $blob = self::generateMessageBlob( $module, $lang );
  75
  76                 if ( !$blob ) {
  77                         return false;
  78                 }
  79
  80                 $dbw = wfGetDB( DB_MASTER );
  81                 $success = $dbw->insert( 'msg_resource', array(
  82                                 'mr_lang' => $lang,
  83                                 'mr_resource' => $name,
  84                                 'mr_blob' => $blob,
  85                                 'mr_timestamp' => $dbw->timestamp()
  86                         ),
  87                         __METHOD__,
  88                         array( 'IGNORE' )
  89                 );
  90
  91                 if ( $success ) {
  92                         if ( $dbw->affectedRows() == 0 ) {
  93                                 // Blob was already present, fetch it
  94                                 $blob = $dbw->selectField( 'msg_resource', 'mr_blob', array(
  95                                                 'mr_resource' => $name,
  96                                                 'mr_lang' => $lang,
  97                                         ),
  98                                         __METHOD__
  99                                 );
 100                         } else {
 101                                 // Update msg_resource_links
 102                                 $rows = array();
 103
 104                                 foreach ( $module->getMessages() as $key ) {
 105                                         $rows[] = array(
 106                                                 'mrl_resource' => $name,
 107                                                 'mrl_message' => $key
 108                                         );
 109                                 }
 110                                 $dbw->insert( 'msg_resource_links', $rows,
 111                                         __METHOD__, array( 'IGNORE' )
 112                                 );
 113                         }
 114                 }
 115
 116                 return $blob;
 117         }
 118
 119         /**
 120          * Update all message blobs for a given module.
 121          *
 122          * @param $name String: module name
 123          * @param $module ResourceLoaderModule object
 124          * @param $lang String: language code (optional)
 125          * @return Mixed: if $lang is set, the new message blob for that language is
 126          *    returned if present. Otherwise, null is returned.
 127          */
 128         public static function updateModule( $name, ResourceLoaderModule $module, $lang = null ) {
 129                 $retval = null;
 130
 131                 // Find all existing blobs for this module
 132                 $dbw = wfGetDB( DB_MASTER );
 133                 $res = $dbw->select( 'msg_resource',
 134                         array( 'mr_lang', 'mr_blob' ),
 135                         array( 'mr_resource' => $name ),
 136                         __METHOD__
 137                 );
 138
 139                 // Build the new msg_resource rows
 140                 $newRows = array();
 141                 $now = $dbw->timestamp();
 142                 // Save the last-processed old and new blobs for later
 143                 $oldBlob = $newBlob = null;
 144
 145                 foreach ( $res as $row ) {
 146                         $oldBlob = $row->mr_blob;
 147                         $newBlob = self::generateMessageBlob( $module, $row->mr_lang );
 148
 149                         if ( $row->mr_lang === $lang ) {
 150                                 $retval = $newBlob;
 151                         }
 152                         $newRows[] = array(
 153                                 'mr_resource' => $name,
 154                                 'mr_lang' => $row->mr_lang,
 155                                 'mr_blob' => $newBlob,
 156                                 'mr_timestamp' => $now
 157                         );
 158                 }
 159
 160                 $dbw->replace( 'msg_resource',
 161                         array( array( 'mr_resource', 'mr_lang' ) ),
 162                         $newRows, __METHOD__
 163                 );
 164
 165                 // Figure out which messages were added and removed
 166                 $oldMessages = array_keys( FormatJson::decode( $oldBlob, true ) );
 167                 $newMessages = array_keys( FormatJson::decode( $newBlob, true ) );
 168                 $added = array_diff( $newMessages, $oldMessages );
 169                 $removed = array_diff( $oldMessages, $newMessages );
 170
 171                 // Delete removed messages, insert added ones
 172                 if ( $removed ) {
 173                         $dbw->delete( 'msg_resource_links', array(
 174                                         'mrl_resource' => $name,
 175                                         'mrl_message' => $removed
 176                                 ), __METHOD__
 177                         );
 178                 }
 179
 180                 $newLinksRows = array();
 181
 182                 foreach ( $added as $message ) {
 183                         $newLinksRows[] = array(
 184                                 'mrl_resource' => $name,
 185                                 'mrl_message' => $message
 186                         );
 187                 }
 188
 189                 if ( $newLinksRows ) {
 190                         $dbw->insert( 'msg_resource_links', $newLinksRows, __METHOD__,
 191                                  array( 'IGNORE' ) // just in case
 192                         );
 193                 }
 194
 195                 return $retval;
 196         }
 197
 198         /**
 199          * Update a single message in all message blobs it occurs in.
 200          *
 201          * @param $key String: message key
 202          */
 203         public static function updateMessage( $key ) {
 204                 $dbw = wfGetDB( DB_MASTER );
 205
 206                 // Keep running until the updates queue is empty.
 207                 // Due to update conflicts, the queue might not be emptied
 208                 // in one iteration.
 209                 $updates = null;
 210                 do {
 211                         $updates = self::getUpdatesForMessage( $key, $updates );
 212
 213                         foreach ( $updates as $k => $update ) {
 214                                 // Update the row on the condition that it
 215                                 // didn't change since we fetched it by putting
 216                                 // the timestamp in the WHERE clause.
 217                                 $success = $dbw->update( 'msg_resource',
 218                                         array(
 219                                                 'mr_blob' => $update['newBlob'],
 220                                                 'mr_timestamp' => $dbw->timestamp() ),
 221                                         array(
 222                                                 'mr_resource' => $update['resource'],
 223                                                 'mr_lang' => $update['lang'],
 224                                                 'mr_timestamp' => $update['timestamp'] ),
 225                                         __METHOD__
 226                                 );
 227
 228                                 // Only requeue conflicted updates.
 229                                 // If update() returned false, don't retry, for
 230                                 // fear of getting into an infinite loop
 231                                 if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 232                                         // Not conflicted
 233                                         unset( $updates[$k] );
 234                                 }
 235                         }
 236                 } while ( count( $updates ) );
 237
 238                 // No need to update msg_resource_links because we didn't add
 239                 // or remove any messages, we just changed their contents.
 240         }
 241
 242         public static function clear() {
 243                 // TODO: Give this some more thought
 244                 // TODO: Is TRUNCATE better?
 245                 $dbw = wfGetDB( DB_MASTER );
 246                 $dbw->delete( 'msg_resource', '*', __METHOD__ );
 247                 $dbw->delete( 'msg_resource_links', '*', __METHOD__ );
 248         }
 249
 250         /**
 251          * Create an update queue for updateMessage()
 252          *
 253          * @param $key String: message key
 254          * @param $prevUpdates Array: updates queue to refresh or null to build a fresh update queue
 255          * @return Array: updates queue
 256          */
 257         private static function getUpdatesForMessage( $key, $prevUpdates = null ) {
 258                 $dbw = wfGetDB( DB_MASTER );
 259
 260                 if ( is_null( $prevUpdates ) ) {
 261                         // Fetch all blobs referencing $key
 262                         $res = $dbw->select(
 263                                 array( 'msg_resource', 'msg_resource_links' ),
 264                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 265                                 array( 'mrl_message' => $key, 'mr_resource=mrl_resource' ),
 266                                 __METHOD__
 267                         );
 268                 } else {
 269                         // Refetch the blobs referenced by $prevUpdates
 270
 271                         // Reorganize the (resource, lang) pairs in the format
 272                         // expected by makeWhereFrom2d()
 273                         $twoD = array();
 274
 275                         foreach ( $prevUpdates as $update ) {
 276                                 $twoD[$update['resource']][$update['lang']] = true;
 277                         }
 278
 279                         $res = $dbw->select( 'msg_resource',
 280                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 281                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 282                                 __METHOD__
 283                         );
 284                 }
 285
 286                 // Build the new updates queue
 287                 $updates = array();
 288
 289                 foreach ( $res as $row ) {
 290                         $updates[] = array(
 291                                 'resource' => $row->mr_resource,
 292                                 'lang' => $row->mr_lang,
 293                                 'timestamp' => $row->mr_timestamp,
 294                                 'newBlob' => self::reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 295                         );
 296                 }
 297
 298                 return $updates;
 299         }
 300
 301         /**
 302          * Reencode a message blob with the updated value for a message
 303          *
 304          * @param $blob String: message blob (JSON object)
 305          * @param $key String: message key
 306          * @param $lang String: language code
 307          * @return Message blob with $key replaced with its new value
 308          */
 309         private static function reencodeBlob( $blob, $key, $lang ) {
 310                 $decoded = FormatJson::decode( $blob, true );
 311                 $decoded[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 312
 313                 return FormatJson::encode( (object)$decoded );
 314         }
 315
 316         /**
 317          * Get the message blobs for a set of modules from the database.
 318          * Modules whose blobs are not in the database are silently dropped.
 319          *
 320          * @param $resourceLoader ResourceLoader object
 321          * @param $modules Array of module names
 322          * @param $lang String: language code
 323          * @return array Array mapping module names to blobs
 324          */
 325         private static function getFromDB( ResourceLoader $resourceLoader, $modules, $lang ) {
 326                 global $wgCacheEpoch;
 327                 $retval = array();
 328                 $dbr = wfGetDB( DB_SLAVE );
 329                 $res = $dbr->select( 'msg_resource',
 330                         array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 331                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 332                         __METHOD__
 333                 );
 334
 335                 foreach ( $res as $row ) {
 336                         $module = $resourceLoader->getModule( $row->mr_resource );
 337                         if ( !$module ) {
 338                                 // This shouldn't be possible
 339                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 340                         }
 341                         // Update the module's blobs if the set of messages changed or if the blob is
 342                         // older than $wgCacheEpoch
 343                         if ( array_keys( FormatJson::decode( $row->mr_blob, true ) ) !== $module->getMessages() ||
 344                                         wfTimestamp( TS_MW, $row->mr_timestamp ) <= $wgCacheEpoch ) {
 345                                 $retval[$row->mr_resource] = self::updateModule( $row->mr_resource, $module, $lang );
 346                         } else {
 347                                 $retval[$row->mr_resource] = $row->mr_blob;
 348                         }
 349                 }
 350
 351                 return $retval;
 352         }
 353
 354         /**
 355          * Generate the message blob for a given module in a given language.
 356          *
 357          * @param $module ResourceLoaderModule object
 358          * @param $lang String: language code
 359          * @return String: JSON object
 360          */
 361         private static function generateMessageBlob( ResourceLoaderModule $module, $lang ) {
 362                 $messages = array();
 363
 364                 foreach ( $module->getMessages() as $key ) {
 365                         $messages[$key] = wfMsgExt( $key, array( 'language' => $lang ) );
 366                 }
 367
 368                 return FormatJson::encode( (object)$messages );
 369         }
 370 }