includes/MessageBlobStore.php

   1 <?php
   2 /**
   3  * Resource message blobs storage used by the resource loader.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @author Roan Kattouw
  22  * @author Trevor Parscal
  23  */
  24
  25 /**
  26  * This class provides access to the resource message blobs storage used by
  27  * the ResourceLoader.
  28  *
  29  * A message blob is a JSON object containing the interface messages for a
  30  * certain resource in a certain language. These message blobs are cached
  31  * in the msg_resource table and automatically invalidated when one of their
  32  * constituent messages or the resource itself is changed.
  33  */
  34 class MessageBlobStore {
  35         /**
  36          * Get the message blobs for a set of modules
  37          *
  38          * @param ResourceLoader $resourceLoader
  39          * @param array $modules Array of module objects keyed by module name
  40          * @param string $lang Language code
  41          * @return array An array mapping module names to message blobs
  42          */
  43         public static function get( ResourceLoader $resourceLoader, $modules, $lang ) {
  44                 wfProfileIn( __METHOD__ );
  45                 if ( !count( $modules ) ) {
  46                         wfProfileOut( __METHOD__ );
  47                         return array();
  48                 }
  49                 // Try getting from the DB first
  50                 $blobs = self::getFromDB( $resourceLoader, array_keys( $modules ), $lang );
  51
  52                 // Generate blobs for any missing modules and store them in the DB
  53                 $missing = array_diff( array_keys( $modules ), array_keys( $blobs ) );
  54                 foreach ( $missing as $name ) {
  55                         $blob = self::insertMessageBlob( $name, $modules[$name], $lang );
  56                         if ( $blob ) {
  57                                 $blobs[$name] = $blob;
  58                         }
  59                 }
  60
  61                 wfProfileOut( __METHOD__ );
  62                 return $blobs;
  63         }
  64
  65         /**
  66          * Generate and insert a new message blob. If the blob was already
  67          * present, it is not regenerated; instead, the preexisting blob
  68          * is fetched and returned.
  69          *
  70          * @param string $name Module name
  71          * @param ResourceLoaderModule $module
  72          * @param string $lang Language code
  73          * @return mixed Message blob or false if the module has no messages
  74          */
  75         public static function insertMessageBlob( $name, ResourceLoaderModule $module, $lang ) {
  76                 $blob = self::generateMessageBlob( $module, $lang );
  77
  78                 if ( !$blob ) {
  79                         return false;
  80                 }
  81
  82                 try {
  83                         $dbw = wfGetDB( DB_MASTER );
  84                         $success = $dbw->insert( 'msg_resource', array(
  85                                         'mr_lang' => $lang,
  86                                         'mr_resource' => $name,
  87                                         'mr_blob' => $blob,
  88                                         'mr_timestamp' => $dbw->timestamp()
  89                                 ),
  90                                 __METHOD__,
  91                                 array( 'IGNORE' )
  92                         );
  93
  94                         if ( $success ) {
  95                                 if ( $dbw->affectedRows() == 0 ) {
  96                                         // Blob was already present, fetch it
  97                                         $blob = $dbw->selectField( 'msg_resource', 'mr_blob', array(
  98                                                         'mr_resource' => $name,
  99                                                         'mr_lang' => $lang,
 100                                                 ),
 101                                                 __METHOD__
 102                                         );
 103                                 } else {
 104                                         // Update msg_resource_links
 105                                         $rows = array();
 106
 107                                         foreach ( $module->getMessages() as $key ) {
 108                                                 $rows[] = array(
 109                                                         'mrl_resource' => $name,
 110                                                         'mrl_message' => $key
 111                                                 );
 112                                         }
 113                                         $dbw->insert( 'msg_resource_links', $rows,
 114                                                 __METHOD__, array( 'IGNORE' )
 115                                         );
 116                                 }
 117                         }
 118                 } catch ( Exception $e ) {
 119                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 120                 }
 121                 return $blob;
 122         }
 123
 124         /**
 125          * Update the message blob for a given module in a given language
 126          *
 127          * @param string $name Module name
 128          * @param ResourceLoaderModule $module
 129          * @param string $lang Language code
 130          * @return string Regenerated message blob, or null if there was no blob for
 131          *   the given module/language pair.
 132          */
 133         public static function updateModule( $name, ResourceLoaderModule $module, $lang ) {
 134                 $dbw = wfGetDB( DB_MASTER );
 135                 $row = $dbw->selectRow( 'msg_resource', 'mr_blob',
 136                         array( 'mr_resource' => $name, 'mr_lang' => $lang ),
 137                         __METHOD__
 138                 );
 139                 if ( !$row ) {
 140                         return null;
 141                 }
 142
 143                 // Save the old and new blobs for later
 144                 $oldBlob = $row->mr_blob;
 145                 $newBlob = self::generateMessageBlob( $module, $lang );
 146
 147                 try {
 148                         $newRow = array(
 149                                 'mr_resource' => $name,
 150                                 'mr_lang' => $lang,
 151                                 'mr_blob' => $newBlob,
 152                                 'mr_timestamp' => $dbw->timestamp()
 153                         );
 154
 155                         $dbw->replace( 'msg_resource',
 156                                 array( array( 'mr_resource', 'mr_lang' ) ),
 157                                 $newRow, __METHOD__
 158                         );
 159
 160                         // Figure out which messages were added and removed
 161                         $oldMessages = array_keys( FormatJson::decode( $oldBlob, true ) );
 162                         $newMessages = array_keys( FormatJson::decode( $newBlob, true ) );
 163                         $added = array_diff( $newMessages, $oldMessages );
 164                         $removed = array_diff( $oldMessages, $newMessages );
 165
 166                         // Delete removed messages, insert added ones
 167                         if ( $removed ) {
 168                                 $dbw->delete( 'msg_resource_links', array(
 169                                                 'mrl_resource' => $name,
 170                                                 'mrl_message' => $removed
 171                                         ), __METHOD__
 172                                 );
 173                         }
 174
 175                         $newLinksRows = array();
 176
 177                         foreach ( $added as $message ) {
 178                                 $newLinksRows[] = array(
 179                                         'mrl_resource' => $name,
 180                                         'mrl_message' => $message
 181                                 );
 182                         }
 183
 184                         if ( $newLinksRows ) {
 185                                 $dbw->insert( 'msg_resource_links', $newLinksRows, __METHOD__,
 186                                         array( 'IGNORE' ) // just in case
 187                                 );
 188                         }
 189                 } catch ( Exception $e ) {
 190                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 191                 }
 192                 return $newBlob;
 193         }
 194
 195         /**
 196          * Update a single message in all message blobs it occurs in.
 197          *
 198          * @param string $key Message key
 199          */
 200         public static function updateMessage( $key ) {
 201                 try {
 202                         $dbw = wfGetDB( DB_MASTER );
 203
 204                         // Keep running until the updates queue is empty.
 205                         // Due to update conflicts, the queue might not be emptied
 206                         // in one iteration.
 207                         $updates = null;
 208                         do {
 209                                 $updates = self::getUpdatesForMessage( $key, $updates );
 210
 211                                 foreach ( $updates as $k => $update ) {
 212                                         // Update the row on the condition that it
 213                                         // didn't change since we fetched it by putting
 214                                         // the timestamp in the WHERE clause.
 215                                         $success = $dbw->update( 'msg_resource',
 216                                                 array(
 217                                                         'mr_blob' => $update['newBlob'],
 218                                                         'mr_timestamp' => $dbw->timestamp() ),
 219                                                 array(
 220                                                         'mr_resource' => $update['resource'],
 221                                                         'mr_lang' => $update['lang'],
 222                                                         'mr_timestamp' => $update['timestamp'] ),
 223                                                 __METHOD__
 224                                         );
 225
 226                                         // Only requeue conflicted updates.
 227                                         // If update() returned false, don't retry, for
 228                                         // fear of getting into an infinite loop
 229                                         if ( !( $success && $dbw->affectedRows() == 0 ) ) {
 230                                                 // Not conflicted
 231                                                 unset( $updates[$k] );
 232                                         }
 233                                 }
 234                         } while ( count( $updates ) );
 235
 236                         // No need to update msg_resource_links because we didn't add
 237                         // or remove any messages, we just changed their contents.
 238                 } catch ( Exception $e ) {
 239                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 240                 }
 241         }
 242
 243         public static function clear() {
 244                 // TODO: Give this some more thought
 245                 try {
 246                         // Not using TRUNCATE, because that needs extra permissions,
 247                         // which maybe not granted to the database user.
 248                         $dbw = wfGetDB( DB_MASTER );
 249                         $dbw->delete( 'msg_resource', '*', __METHOD__ );
 250                         $dbw->delete( 'msg_resource_links', '*', __METHOD__ );
 251                 } catch ( Exception $e ) {
 252                         wfDebug( __METHOD__ . " failed to update DB: $e\n" );
 253                 }
 254         }
 255
 256         /**
 257          * Create an update queue for updateMessage()
 258          *
 259          * @param string $key Message key
 260          * @param array $prevUpdates Updates queue to refresh or null to build a fresh update queue
 261          * @return array Updates queue
 262          */
 263         private static function getUpdatesForMessage( $key, $prevUpdates = null ) {
 264                 $dbw = wfGetDB( DB_MASTER );
 265
 266                 if ( is_null( $prevUpdates ) ) {
 267                         // Fetch all blobs referencing $key
 268                         $res = $dbw->select(
 269                                 array( 'msg_resource', 'msg_resource_links' ),
 270                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 271                                 array( 'mrl_message' => $key, 'mr_resource=mrl_resource' ),
 272                                 __METHOD__
 273                         );
 274                 } else {
 275                         // Refetch the blobs referenced by $prevUpdates
 276
 277                         // Reorganize the (resource, lang) pairs in the format
 278                         // expected by makeWhereFrom2d()
 279                         $twoD = array();
 280
 281                         foreach ( $prevUpdates as $update ) {
 282                                 $twoD[$update['resource']][$update['lang']] = true;
 283                         }
 284
 285                         $res = $dbw->select( 'msg_resource',
 286                                 array( 'mr_resource', 'mr_lang', 'mr_blob', 'mr_timestamp' ),
 287                                 $dbw->makeWhereFrom2d( $twoD, 'mr_resource', 'mr_lang' ),
 288                                 __METHOD__
 289                         );
 290                 }
 291
 292                 // Build the new updates queue
 293                 $updates = array();
 294
 295                 foreach ( $res as $row ) {
 296                         $updates[] = array(
 297                                 'resource' => $row->mr_resource,
 298                                 'lang' => $row->mr_lang,
 299                                 'timestamp' => $row->mr_timestamp,
 300                                 'newBlob' => self::reencodeBlob( $row->mr_blob, $key, $row->mr_lang )
 301                         );
 302                 }
 303
 304                 return $updates;
 305         }
 306
 307         /**
 308          * Reencode a message blob with the updated value for a message
 309          *
 310          * @param string $blob Message blob (JSON object)
 311          * @param string $key Message key
 312          * @param string $lang Language code
 313          * @return string Message blob with $key replaced with its new value
 314          */
 315         private static function reencodeBlob( $blob, $key, $lang ) {
 316                 $decoded = FormatJson::decode( $blob, true );
 317                 $decoded[$key] = wfMessage( $key )->inLanguage( $lang )->plain();
 318
 319                 return FormatJson::encode( (object)$decoded );
 320         }
 321
 322         /**
 323          * Get the message blobs for a set of modules from the database.
 324          * Modules whose blobs are not in the database are silently dropped.
 325          *
 326          * @param ResourceLoader $resourceLoader
 327          * @param array $modules Array of module names
 328          * @param string $lang Language code
 329          * @throws MWException
 330          * @return array Array mapping module names to blobs
 331          */
 332         private static function getFromDB( ResourceLoader $resourceLoader, $modules, $lang ) {
 333                 global $wgCacheEpoch;
 334
 335                 $retval = array();
 336                 $dbr = wfGetDB( DB_SLAVE );
 337                 $res = $dbr->select( 'msg_resource',
 338                         array( 'mr_blob', 'mr_resource', 'mr_timestamp' ),
 339                         array( 'mr_resource' => $modules, 'mr_lang' => $lang ),
 340                         __METHOD__
 341                 );
 342
 343                 foreach ( $res as $row ) {
 344                         $module = $resourceLoader->getModule( $row->mr_resource );
 345                         if ( !$module ) {
 346                                 // This shouldn't be possible
 347                                 throw new MWException( __METHOD__ . ' passed an invalid module name' );
 348                         }
 349
 350                         // Update the module's blobs if the set of messages changed or if the blob is
 351                         // older than $wgCacheEpoch
 352                         $keys = array_keys( FormatJson::decode( $row->mr_blob, true ) );
 353                         $values = array_values( array_unique( $module->getMessages() ) );
 354                         if ( $keys !== $values
 355                                 || wfTimestamp( TS_MW, $row->mr_timestamp ) <= $wgCacheEpoch
 356                         ) {
 357                                 $retval[$row->mr_resource] = self::updateModule( $row->mr_resource, $module, $lang );
 358                         } else {
 359                                 $retval[$row->mr_resource] = $row->mr_blob;
 360                         }
 361                 }
 362
 363                 return $retval;
 364         }
 365
 366         /**
 367          * Generate the message blob for a given module in a given language.
 368          *
 369          * @param ResourceLoaderModule $module
 370          * @param string $lang Language code
 371          * @return string JSON object
 372          */
 373         private static function generateMessageBlob( ResourceLoaderModule $module, $lang ) {
 374                 $messages = array();
 375
 376                 foreach ( $module->getMessages() as $key ) {
 377                         $messages[$key] = wfMessage( $key )->inLanguage( $lang )->plain();
 378                 }
 379
 380                 return FormatJson::encode( (object)$messages );
 381         }
 382 }