includes/Storage/NameTableStore.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  * @file
  19  */
  20
  21 namespace MediaWiki\Storage;
  22
  23 use IExpiringStore;
  24 use Psr\Log\LoggerInterface;
  25 use WANObjectCache;
  26 use Wikimedia\Assert\Assert;
  27 use Wikimedia\Rdbms\Database;
  28 use Wikimedia\Rdbms\IDatabase;
  29 use Wikimedia\Rdbms\ILoadBalancer;
  30 use Wikimedia\Rdbms\LoadBalancer;
  31
  32 /**
  33  * @author Addshore
  34  * @since 1.31
  35  */
  36 class NameTableStore {
  37
  38         /** @var LoadBalancer */
  39         private $loadBalancer;
  40
  41         /** @var WANObjectCache */
  42         private $cache;
  43
  44         /** @var LoggerInterface */
  45         private $logger;
  46
  47         /** @var string[] */
  48         private $tableCache = null;
  49
  50         /** @var bool|string */
  51         private $wikiId = false;
  52
  53         /** @var int */
  54         private $cacheTTL;
  55
  56         /** @var string */
  57         private $table;
  58         /** @var string */
  59         private $idField;
  60         /** @var string */
  61         private $nameField;
  62         /** @var null|callable */
  63         private $normalizationCallback = null;
  64         /** @var null|callable */
  65         private $insertCallback = null;
  66
  67         /**
  68          * @param ILoadBalancer $dbLoadBalancer A load balancer for acquiring database connections
  69          * @param WANObjectCache $cache A cache manager for caching data
  70          * @param LoggerInterface $logger
  71          * @param string $table
  72          * @param string $idField
  73          * @param string $nameField
  74          * @param callable|null $normalizationCallback Normalization to be applied to names before being
  75          * saved or queried. This should be a callback that accepts and returns a single string.
  76          * @param bool|string $wikiId The ID of the target wiki database. Use false for the local wiki.
  77          * @param callable|null $insertCallback Callback to change insert fields accordingly.
  78          * This parameter was introduced in 1.32
  79          */
  80         public function __construct(
  81                 ILoadBalancer $dbLoadBalancer,
  82                 WANObjectCache $cache,
  83                 LoggerInterface $logger,
  84                 $table,
  85                 $idField,
  86                 $nameField,
  87                 callable $normalizationCallback = null,
  88                 $wikiId = false,
  89                 callable $insertCallback = null
  90         ) {
  91                 $this->loadBalancer = $dbLoadBalancer;
  92                 $this->cache = $cache;
  93                 $this->logger = $logger;
  94                 $this->table = $table;
  95                 $this->idField = $idField;
  96                 $this->nameField = $nameField;
  97                 $this->normalizationCallback = $normalizationCallback;
  98                 $this->wikiId = $wikiId;
  99                 $this->cacheTTL = IExpiringStore::TTL_MONTH;
 100                 $this->insertCallback = $insertCallback;
 101         }
 102
 103         /**
 104          * @param int $index A database index, like DB_MASTER or DB_REPLICA
 105          * @param int $flags Database connection flags
 106          *
 107          * @return IDatabase
 108          */
 109         private function getDBConnection( $index, $flags = 0 ) {
 110                 return $this->loadBalancer->getConnection( $index, [], $this->wikiId, $flags );
 111         }
 112
 113         /**
 114          * Gets the cache key for names.
 115          *
 116          * The cache key is constructed based on the wiki ID passed to the constructor, and allows
 117          * sharing of name tables cached for a specific database between wikis.
 118          *
 119          * @return string
 120          */
 121         private function getCacheKey() {
 122                 return $this->cache->makeGlobalKey(
 123                         'NameTableSqlStore',
 124                         $this->table,
 125                         $this->loadBalancer->resolveDomainID( $this->wikiId )
 126                 );
 127         }
 128
 129         /**
 130          * @param string $name
 131          * @return string
 132          */
 133         private function normalizeName( $name ) {
 134                 if ( $this->normalizationCallback === null ) {
 135                         return $name;
 136                 }
 137                 return call_user_func( $this->normalizationCallback, $name );
 138         }
 139
 140         /**
 141          * Acquire the id of the given name.
 142          * This creates a row in the table if it doesn't already exist.
 143          *
 144          * @param string $name
 145          * @throws NameTableAccessException
 146          * @return int
 147          */
 148         public function acquireId( $name ) {
 149                 Assert::parameterType( 'string', $name, '$name' );
 150                 $name = $this->normalizeName( $name );
 151
 152                 $table = $this->getTableFromCachesOrReplica();
 153                 $searchResult = array_search( $name, $table, true );
 154                 if ( $searchResult === false ) {
 155                         $id = $this->store( $name );
 156                         if ( $id === null ) {
 157                                 // RACE: $name was already in the db, probably just inserted, so load from master
 158                                 // Use DBO_TRX to avoid missing inserts due to other threads or REPEATABLE-READs
 159                                 $table = $this->loadTable(
 160                                         $this->getDBConnection( DB_MASTER, LoadBalancer::CONN_TRX_AUTOCOMMIT )
 161                                 );
 162                                 $searchResult = array_search( $name, $table, true );
 163                                 if ( $searchResult === false ) {
 164                                         // Insert failed due to IGNORE flag, but DB_MASTER didn't give us the data
 165                                         $m = "No insert possible but master didn't give us a record for " .
 166                                                 "'{$name}' in '{$this->table}'";
 167                                         $this->logger->error( $m );
 168                                         throw new NameTableAccessException( $m );
 169                                 }
 170                                 $this->purgeWANCache(
 171                                         function () {
 172                                                 $this->cache->reap( $this->getCacheKey(), INF );
 173                                         }
 174                                 );
 175                         } else {
 176                                 $table[$id] = $name;
 177                                 $searchResult = $id;
 178                                 // As store returned an ID we know we inserted so delete from WAN cache
 179                                 $this->purgeWANCache(
 180                                         function () {
 181                                                 $this->cache->delete( $this->getCacheKey() );
 182                                         }
 183                                 );
 184                         }
 185                         $this->tableCache = $table;
 186                 }
 187
 188                 return $searchResult;
 189         }
 190
 191         /**
 192          * Get the id of the given name.
 193          * If the name doesn't exist this will throw.
 194          * This should be used in cases where we believe the name already exists or want to check for
 195          * existence.
 196          *
 197          * @param string $name
 198          * @throws NameTableAccessException The name does not exist
 199          * @return int Id
 200          */
 201         public function getId( $name ) {
 202                 Assert::parameterType( 'string', $name, '$name' );
 203                 $name = $this->normalizeName( $name );
 204
 205                 $table = $this->getTableFromCachesOrReplica();
 206                 $searchResult = array_search( $name, $table, true );
 207
 208                 if ( $searchResult !== false ) {
 209                         return $searchResult;
 210                 }
 211
 212                 throw NameTableAccessException::newFromDetails( $this->table, 'name', $name );
 213         }
 214
 215         /**
 216          * Get the name of the given id.
 217          * If the id doesn't exist this will throw.
 218          * This should be used in cases where we believe the id already exists.
 219          *
 220          * Note: Calls to this method will result in a master select for non existing IDs.
 221          *
 222          * @param int $id
 223          * @throws NameTableAccessException The id does not exist
 224          * @return string name
 225          */
 226         public function getName( $id ) {
 227                 Assert::parameterType( 'integer', $id, '$id' );
 228
 229                 $table = $this->getTableFromCachesOrReplica();
 230                 if ( array_key_exists( $id, $table ) ) {
 231                         return $table[$id];
 232                 }
 233
 234                 $table = $this->cache->getWithSetCallback(
 235                         $this->getCacheKey(),
 236                         $this->cacheTTL,
 237                         function ( $oldValue, &$ttl, &$setOpts ) use ( $id ) {
 238                                 // Check if cached value is up-to-date enough to have $id
 239                                 if ( is_array( $oldValue ) && array_key_exists( $id, $oldValue ) ) {
 240                                         // Completely leave the cache key alone
 241                                         $ttl = WANObjectCache::TTL_UNCACHEABLE;
 242                                         // Use the old value
 243                                         return $oldValue;
 244                                 }
 245                                 // Regenerate from replica DB, and master DB if needed
 246                                 foreach ( [ DB_REPLICA, DB_MASTER ] as $source ) {
 247                                         // Log a fallback to master
 248                                         if ( $source === DB_MASTER ) {
 249                                                 $this->logger->info(
 250                                                         __METHOD__ . 'falling back to master select from ' .
 251                                                         $this->table . ' with id ' . $id
 252                                                 );
 253                                         }
 254                                         $db = $this->getDBConnection( $source );
 255                                         $cacheSetOpts = Database::getCacheSetOptions( $db );
 256                                         $table = $this->loadTable( $db );
 257                                         if ( array_key_exists( $id, $table ) ) {
 258                                                 break; // found it
 259                                         }
 260                                 }
 261                                 // Use the value from last source checked
 262                                 $setOpts += $cacheSetOpts;
 263
 264                                 return $table;
 265                         },
 266                         [ 'minAsOf' => INF ] // force callback run
 267                 );
 268
 269                 $this->tableCache = $table;
 270
 271                 if ( array_key_exists( $id, $table ) ) {
 272                         return $table[$id];
 273                 }
 274
 275                 throw NameTableAccessException::newFromDetails( $this->table, 'id', $id );
 276         }
 277
 278         /**
 279          * Get the whole table, in no particular order as a map of ids to names.
 280          * This method could be subject to DB or cache lag.
 281          *
 282          * @return string[] keys are the name ids, values are the names themselves
 283          *  Example: [ 1 => 'foo', 3 => 'bar' ]
 284          */
 285         public function getMap() {
 286                 return $this->getTableFromCachesOrReplica();
 287         }
 288
 289         /**
 290          * @return string[]
 291          */
 292         private function getTableFromCachesOrReplica() {
 293                 if ( $this->tableCache !== null ) {
 294                         return $this->tableCache;
 295                 }
 296
 297                 $table = $this->cache->getWithSetCallback(
 298                         $this->getCacheKey(),
 299                         $this->cacheTTL,
 300                         function ( $oldValue, &$ttl, &$setOpts ) {
 301                                 $dbr = $this->getDBConnection( DB_REPLICA );
 302                                 $setOpts += Database::getCacheSetOptions( $dbr );
 303                                 return $this->loadTable( $dbr );
 304                         }
 305                 );
 306
 307                 $this->tableCache = $table;
 308
 309                 return $table;
 310         }
 311
 312         /**
 313          * Reap the WANCache entry for this table.
 314          *
 315          * @param callable $purgeCallback callback to 'purge' the WAN cache
 316          */
 317         private function purgeWANCache( $purgeCallback ) {
 318                 // If the LB has no DB changes don't both with onTransactionPreCommitOrIdle
 319                 if ( !$this->loadBalancer->hasOrMadeRecentMasterChanges() ) {
 320                         $purgeCallback();
 321                         return;
 322                 }
 323
 324                 $this->getDBConnection( DB_MASTER )
 325                         ->onTransactionPreCommitOrIdle( $purgeCallback, __METHOD__ );
 326         }
 327
 328         /**
 329          * Gets the table from the db
 330          *
 331          * @param IDatabase $db
 332          *
 333          * @return string[]
 334          */
 335         private function loadTable( IDatabase $db ) {
 336                 $result = $db->select(
 337                         $this->table,
 338                         [
 339                                 'id' => $this->idField,
 340                                 'name' => $this->nameField
 341                         ],
 342                         [],
 343                         __METHOD__,
 344                         [ 'ORDER BY' => 'id' ]
 345                 );
 346
 347                 $assocArray = [];
 348                 foreach ( $result as $row ) {
 349                         $assocArray[$row->id] = $row->name;
 350                 }
 351
 352                 return $assocArray;
 353         }
 354
 355         /**
 356          * Stores the given name in the DB, returning the ID when an insert occurs.
 357          *
 358          * @param string $name
 359          * @return int|null int if we know the ID, null if we don't
 360          */
 361         private function store( $name ) {
 362                 Assert::parameterType( 'string', $name, '$name' );
 363                 Assert::parameter( $name !== '', '$name', 'should not be an empty string' );
 364                 // Note: this is only called internally so normalization of $name has already occurred.
 365
 366                 $dbw = $this->getDBConnection( DB_MASTER );
 367
 368                 $dbw->insert(
 369                         $this->table,
 370                         $this->getFieldsToStore( $name ),
 371                         __METHOD__,
 372                         [ 'IGNORE' ]
 373                 );
 374
 375                 if ( $dbw->affectedRows() === 0 ) {
 376                         $this->logger->info(
 377                                 'Tried to insert name into table ' . $this->table . ', but value already existed.'
 378                         );
 379                         return null;
 380                 }
 381
 382                 return $dbw->insertId();
 383         }
 384
 385         /**
 386          * @param string $name
 387          * @return array
 388          */
 389         private function getFieldsToStore( $name ) {
 390                 $fields = [ $this->nameField => $name ];
 391                 if ( $this->insertCallback !== null ) {
 392                         $fields = call_user_func( $this->insertCallback, $fields );
 393                 }
 394                 return $fields;
 395         }
 396
 397 }