includes/CommentStore.php

   1 <?php
   2 /**
   3  * Manage storage of comments in the database
   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  */
  22
  23 use MediaWiki\MediaWikiServices;
  24 use Wikimedia\Rdbms\IDatabase;
  25
  26 /**
  27  * CommentStore handles storage of comments (edit summaries, log reasons, etc)
  28  * in the database.
  29  * @since 1.30
  30  */
  31 class CommentStore {
  32
  33         /**
  34          * Maximum length of a comment in UTF-8 characters. Longer comments will be truncated.
  35          * @note This must be at least 255 and not greater than floor( MAX_COMMENT_LENGTH / 4 ).
  36          */
  37         const COMMENT_CHARACTER_LIMIT = 500;
  38
  39         /**
  40          * Maximum length of a comment in bytes. Longer comments will be truncated.
  41          * @note This value is determined by the size of the underlying database field,
  42          *  currently BLOB in MySQL/MariaDB.
  43          */
  44         const MAX_COMMENT_LENGTH = 65535;
  45
  46         /**
  47          * Maximum length of serialized data in bytes. Longer data will result in an exception.
  48          * @note This value is determined by the size of the underlying database field,
  49          *  currently BLOB in MySQL/MariaDB.
  50          */
  51         const MAX_DATA_LENGTH = 65535;
  52
  53         /**
  54          * Define fields that use temporary tables for transitional purposes
  55          * @var array Keys are '$key', values are arrays with these possible fields:
  56          *  - table: Temporary table name
  57          *  - pk: Temporary table column referring to the main table's primary key
  58          *  - field: Temporary table column referring comment.comment_id
  59          *  - joinPK: Main table's primary key
  60          *  - stage: Migration stage
  61          *  - deprecatedIn: Version when using insertWithTempTable() was deprecated
  62          */
  63         protected $tempTables = [
  64                 'rev_comment' => [
  65                         'table' => 'revision_comment_temp',
  66                         'pk' => 'revcomment_rev',
  67                         'field' => 'revcomment_comment_id',
  68                         'joinPK' => 'rev_id',
  69                         'stage' => MIGRATION_OLD,
  70                         'deprecatedIn' => null,
  71                 ],
  72                 'img_description' => [
  73                         'table' => 'image_comment_temp',
  74                         'pk' => 'imgcomment_name',
  75                         'field' => 'imgcomment_description_id',
  76                         'joinPK' => 'img_name',
  77                         'stage' => MIGRATION_WRITE_NEW,
  78                         'deprecatedIn' => '1.32',
  79                 ],
  80         ];
  81
  82         /**
  83          * @since 1.30
  84          * @deprecated in 1.31
  85          * @var string|null
  86          */
  87         protected $key = null;
  88
  89         /** @var int One of the MIGRATION_* constants */
  90         protected $stage;
  91
  92         /** @var array[] Cache for `self::getJoin()` */
  93         protected $joinCache = [];
  94
  95         /** @var Language Language to use for comment truncation */
  96         protected $lang;
  97
  98         /**
  99          * @param Language $lang Language to use for comment truncation. Defaults
 100          *  to content language.
 101          * @param int $migrationStage One of the MIGRATION_* constants
 102          */
 103         public function __construct( Language $lang, $migrationStage ) {
 104                 $this->stage = $migrationStage;
 105                 $this->lang = $lang;
 106         }
 107
 108         /**
 109          * Static constructor for easier chaining
 110          * @deprecated in 1.31 Should not be constructed with a $key, use CommentStore::getStore
 111          * @param string $key A key such as "rev_comment" identifying the comment
 112          *  field being fetched.
 113          * @return CommentStore
 114          */
 115         public static function newKey( $key ) {
 116                 global $wgCommentTableSchemaMigrationStage;
 117                 wfDeprecated( __METHOD__, '1.31' );
 118                 $store = new CommentStore( MediaWikiServices::getInstance()->getContentLanguage(),
 119                         $wgCommentTableSchemaMigrationStage );
 120                 $store->key = $key;
 121                 return $store;
 122         }
 123
 124         /**
 125          * @since 1.31
 126          * @deprecated in 1.31 Use DI to inject a CommentStore instance into your class.
 127          * @return CommentStore
 128          */
 129         public static function getStore() {
 130                 return MediaWikiServices::getInstance()->getCommentStore();
 131         }
 132
 133         /**
 134          * Compat method allowing use of self::newKey until removed.
 135          * @param string|null $methodKey
 136          * @throws InvalidArgumentException
 137          * @return string
 138          */
 139         private function getKey( $methodKey = null ) {
 140                 $key = $this->key ?? $methodKey;
 141                 if ( $key === null ) {
 142                         // @codeCoverageIgnoreStart
 143                         throw new InvalidArgumentException( '$key should not be null' );
 144                         // @codeCoverageIgnoreEnd
 145                 }
 146                 return $key;
 147         }
 148
 149         /**
 150          * Get SELECT fields for the comment key
 151          *
 152          * Each resulting row should be passed to `self::getCommentLegacy()` to get the
 153          * actual comment.
 154          *
 155          * @note Use of this method may require a subsequent database query to
 156          *  actually fetch the comment. If possible, use `self::getJoin()` instead.
 157          *
 158          * @since 1.30
 159          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 160          * @param string|null $key A key such as "rev_comment" identifying the comment
 161          *  field being fetched.
 162          * @return string[] to include in the `$vars` to `IDatabase->select()`. All
 163          *  fields are aliased, so `+` is safe to use.
 164          */
 165         public function getFields( $key = null ) {
 166                 $key = $this->getKey( $key );
 167                 $fields = [];
 168                 if ( $this->stage === MIGRATION_OLD ) {
 169                         $fields["{$key}_text"] = $key;
 170                         $fields["{$key}_data"] = 'NULL';
 171                         $fields["{$key}_cid"] = 'NULL';
 172                 } else {
 173                         if ( $this->stage < MIGRATION_NEW ) {
 174                                 $fields["{$key}_old"] = $key;
 175                         }
 176
 177                         $tempTableStage = isset( $this->tempTables[$key] )
 178                                 ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 179                         if ( $tempTableStage < MIGRATION_NEW ) {
 180                                 $fields["{$key}_pk"] = $this->tempTables[$key]['joinPK'];
 181                         }
 182                         if ( $tempTableStage > MIGRATION_OLD ) {
 183                                 $fields["{$key}_id"] = "{$key}_id";
 184                         }
 185                 }
 186                 return $fields;
 187         }
 188
 189         /**
 190          * Get SELECT fields and joins for the comment key
 191          *
 192          * Each resulting row should be passed to `self::getComment()` to get the
 193          * actual comment.
 194          *
 195          * @since 1.30
 196          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 197          * @param string|null $key A key such as "rev_comment" identifying the comment
 198          *  field being fetched.
 199          * @return array With three keys:
 200          *   - tables: (string[]) to include in the `$table` to `IDatabase->select()`
 201          *   - fields: (string[]) to include in the `$vars` to `IDatabase->select()`
 202          *   - joins: (array) to include in the `$join_conds` to `IDatabase->select()`
 203          *  All tables, fields, and joins are aliased, so `+` is safe to use.
 204          */
 205         public function getJoin( $key = null ) {
 206                 $key = $this->getKey( $key );
 207                 if ( !array_key_exists( $key, $this->joinCache ) ) {
 208                         $tables = [];
 209                         $fields = [];
 210                         $joins = [];
 211
 212                         if ( $this->stage === MIGRATION_OLD ) {
 213                                 $fields["{$key}_text"] = $key;
 214                                 $fields["{$key}_data"] = 'NULL';
 215                                 $fields["{$key}_cid"] = 'NULL';
 216                         } else {
 217                                 $join = $this->stage === MIGRATION_NEW ? 'JOIN' : 'LEFT JOIN';
 218
 219                                 $tempTableStage = isset( $this->tempTables[$key] )
 220                                         ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 221                                 if ( $tempTableStage < MIGRATION_NEW ) {
 222                                         $t = $this->tempTables[$key];
 223                                         $alias = "temp_$key";
 224                                         $tables[$alias] = $t['table'];
 225                                         $joins[$alias] = [ $join, "{$alias}.{$t['pk']} = {$t['joinPK']}" ];
 226                                         if ( $tempTableStage === MIGRATION_OLD ) {
 227                                                 $joinField = "{$alias}.{$t['field']}";
 228                                         } else {
 229                                                 $joins[$alias][0] = 'LEFT JOIN';
 230                                                 $joinField = "(CASE WHEN {$key}_id != 0 THEN {$key}_id ELSE {$alias}.{$t['field']} END)";
 231                                         }
 232                                 } else {
 233                                         $joinField = "{$key}_id";
 234                                 }
 235
 236                                 $alias = "comment_$key";
 237                                 $tables[$alias] = 'comment';
 238                                 $joins[$alias] = [ $join, "{$alias}.comment_id = {$joinField}" ];
 239
 240                                 if ( $this->stage === MIGRATION_NEW ) {
 241                                         $fields["{$key}_text"] = "{$alias}.comment_text";
 242                                 } else {
 243                                         $fields["{$key}_text"] = "COALESCE( {$alias}.comment_text, $key )";
 244                                 }
 245                                 $fields["{$key}_data"] = "{$alias}.comment_data";
 246                                 $fields["{$key}_cid"] = "{$alias}.comment_id";
 247                         }
 248
 249                         $this->joinCache[$key] = [
 250                                 'tables' => $tables,
 251                                 'fields' => $fields,
 252                                 'joins' => $joins,
 253                         ];
 254                 }
 255
 256                 return $this->joinCache[$key];
 257         }
 258
 259         /**
 260          * Extract the comment from a row
 261          *
 262          * Shared implementation for getComment() and getCommentLegacy()
 263          *
 264          * @param IDatabase|null $db Database handle for getCommentLegacy(), or null for getComment()
 265          * @param string $key A key such as "rev_comment" identifying the comment
 266          *  field being fetched.
 267          * @param object|array $row
 268          * @param bool $fallback
 269          * @return CommentStoreComment
 270          */
 271         private function getCommentInternal( IDatabase $db = null, $key, $row, $fallback = false ) {
 272                 $row = (array)$row;
 273                 if ( array_key_exists( "{$key}_text", $row ) && array_key_exists( "{$key}_data", $row ) ) {
 274                         $cid = $row["{$key}_cid"] ?? null;
 275                         $text = $row["{$key}_text"];
 276                         $data = $row["{$key}_data"];
 277                 } elseif ( $this->stage === MIGRATION_OLD ) {
 278                         $cid = null;
 279                         if ( $fallback && isset( $row[$key] ) ) {
 280                                 wfLogWarning( "Using deprecated fallback handling for comment $key" );
 281                                 $text = $row[$key];
 282                         } else {
 283                                 wfLogWarning( "Missing {$key}_text and {$key}_data fields in row with MIGRATION_OLD" );
 284                                 $text = '';
 285                         }
 286                         $data = null;
 287                 } else {
 288                         $tempTableStage = isset( $this->tempTables[$key] )
 289                                 ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 290                         $row2 = null;
 291                         if ( $tempTableStage > MIGRATION_OLD && array_key_exists( "{$key}_id", $row ) ) {
 292                                 if ( !$db ) {
 293                                         throw new InvalidArgumentException(
 294                                                 "\$row does not contain fields needed for comment $key and getComment(), but "
 295                                                 . "does have fields for getCommentLegacy()"
 296                                         );
 297                                 }
 298                                 $id = $row["{$key}_id"];
 299                                 $row2 = $db->selectRow(
 300                                         'comment',
 301                                         [ 'comment_id', 'comment_text', 'comment_data' ],
 302                                         [ 'comment_id' => $id ],
 303                                         __METHOD__
 304                                 );
 305                         }
 306                         if ( !$row2 && $tempTableStage < MIGRATION_NEW && array_key_exists( "{$key}_pk", $row ) ) {
 307                                 if ( !$db ) {
 308                                         throw new InvalidArgumentException(
 309                                                 "\$row does not contain fields needed for comment $key and getComment(), but "
 310                                                 . "does have fields for getCommentLegacy()"
 311                                         );
 312                                 }
 313                                 $t = $this->tempTables[$key];
 314                                 $id = $row["{$key}_pk"];
 315                                 $row2 = $db->selectRow(
 316                                         [ $t['table'], 'comment' ],
 317                                         [ 'comment_id', 'comment_text', 'comment_data' ],
 318                                         [ $t['pk'] => $id ],
 319                                         __METHOD__,
 320                                         [],
 321                                         [ 'comment' => [ 'JOIN', [ "comment_id = {$t['field']}" ] ] ]
 322                                 );
 323                         }
 324                         if ( $row2 === null && $fallback && isset( $row[$key] ) ) {
 325                                 wfLogWarning( "Using deprecated fallback handling for comment $key" );
 326                                 $row2 = (object)[ 'comment_text' => $row[$key], 'comment_data' => null ];
 327                         }
 328                         if ( $row2 === null ) {
 329                                 throw new InvalidArgumentException( "\$row does not contain fields needed for comment $key" );
 330                         }
 331
 332                         if ( $row2 ) {
 333                                 $cid = $row2->comment_id;
 334                                 $text = $row2->comment_text;
 335                                 $data = $row2->comment_data;
 336                         } elseif ( $this->stage < MIGRATION_NEW && array_key_exists( "{$key}_old", $row ) ) {
 337                                 $cid = null;
 338                                 $text = $row["{$key}_old"];
 339                                 $data = null;
 340                         } else {
 341                                 // @codeCoverageIgnoreStart
 342                                 wfLogWarning( "Missing comment row for $key, id=$id" );
 343                                 $cid = null;
 344                                 $text = '';
 345                                 $data = null;
 346                                 // @codeCoverageIgnoreEnd
 347                         }
 348                 }
 349
 350                 $msg = null;
 351                 if ( $data !== null ) {
 352                         $data = FormatJson::decode( $data, true );
 353                         if ( !is_array( $data ) ) {
 354                                 // @codeCoverageIgnoreStart
 355                                 wfLogWarning( "Invalid JSON object in comment: $data" );
 356                                 $data = null;
 357                                 // @codeCoverageIgnoreEnd
 358                         } else {
 359                                 if ( isset( $data['_message'] ) ) {
 360                                         $msg = self::decodeMessage( $data['_message'] )
 361                                                 ->setInterfaceMessageFlag( true );
 362                                 }
 363                                 if ( !empty( $data['_null'] ) ) {
 364                                         $data = null;
 365                                 } else {
 366                                         foreach ( $data as $k => $v ) {
 367                                                 if ( substr( $k, 0, 1 ) === '_' ) {
 368                                                         unset( $data[$k] );
 369                                                 }
 370                                         }
 371                                 }
 372                         }
 373                 }
 374
 375                 return new CommentStoreComment( $cid, $text, $msg, $data );
 376         }
 377
 378         /**
 379          * Extract the comment from a row
 380          *
 381          * Use `self::getJoin()` to ensure the row contains the needed data.
 382          *
 383          * If you need to fake a comment in a row for some reason, set fields
 384          * `{$key}_text` (string) and `{$key}_data` (JSON string or null).
 385          *
 386          * @since 1.30
 387          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 388          * @param string $key A key such as "rev_comment" identifying the comment
 389          *  field being fetched.
 390          * @param object|array|null $row Result row.
 391          * @param bool $fallback If true, fall back as well as possible instead of throwing an exception.
 392          * @return CommentStoreComment
 393          */
 394         public function getComment( $key, $row = null, $fallback = false ) {
 395                 // Compat for method sig change in 1.31 (introduction of $key)
 396                 if ( $this->key !== null ) {
 397                         $fallback = $row;
 398                         $row = $key;
 399                         $key = $this->getKey();
 400                 }
 401                 if ( $row === null ) {
 402                         // @codeCoverageIgnoreStart
 403                         throw new InvalidArgumentException( '$row must not be null' );
 404                         // @codeCoverageIgnoreEnd
 405                 }
 406                 return $this->getCommentInternal( null, $key, $row, $fallback );
 407         }
 408
 409         /**
 410          * Extract the comment from a row, with legacy lookups.
 411          *
 412          * If `$row` might have been generated using `self::getFields()` rather
 413          * than `self::getJoin()`, use this. Prefer `self::getComment()` if you
 414          * know callers used `self::getJoin()` for the row fetch.
 415          *
 416          * If you need to fake a comment in a row for some reason, set fields
 417          * `{$key}_text` (string) and `{$key}_data` (JSON string or null).
 418          *
 419          * @since 1.30
 420          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 421          * @param IDatabase $db Database handle to use for lookup
 422          * @param string $key A key such as "rev_comment" identifying the comment
 423          *  field being fetched.
 424          * @param object|array|null $row Result row.
 425          * @param bool $fallback If true, fall back as well as possible instead of throwing an exception.
 426          * @return CommentStoreComment
 427          */
 428         public function getCommentLegacy( IDatabase $db, $key, $row = null, $fallback = false ) {
 429                 // Compat for method sig change in 1.31 (introduction of $key)
 430                 if ( $this->key !== null ) {
 431                         $fallback = $row;
 432                         $row = $key;
 433                         $key = $this->getKey();
 434                 }
 435                 if ( $row === null ) {
 436                         // @codeCoverageIgnoreStart
 437                         throw new InvalidArgumentException( '$row must not be null' );
 438                         // @codeCoverageIgnoreEnd
 439                 }
 440                 return $this->getCommentInternal( $db, $key, $row, $fallback );
 441         }
 442
 443         /**
 444          * Create a new CommentStoreComment, inserting it into the database if necessary
 445          *
 446          * If a comment is going to be passed to `self::insert()` or the like
 447          * multiple times, it will be more efficient to pass a CommentStoreComment
 448          * once rather than making `self::insert()` do it every time through.
 449          *
 450          * @note When passing a CommentStoreComment, this may set `$comment->id` if
 451          *  it's not already set. If `$comment->id` is already set, it will not be
 452          *  verified that the specified comment actually exists or that it
 453          *  corresponds to the comment text, message, and/or data in the
 454          *  CommentStoreComment.
 455          * @param IDatabase $dbw Database handle to insert on. Unused if `$comment`
 456          *  is a CommentStoreComment and `$comment->id` is set.
 457          * @param string|Message|CommentStoreComment $comment Comment text or Message object, or
 458          *  a CommentStoreComment.
 459          * @param array|null $data Structured data to store. Keys beginning with '_' are reserved.
 460          *  Ignored if $comment is a CommentStoreComment.
 461          * @return CommentStoreComment
 462          */
 463         public function createComment( IDatabase $dbw, $comment, array $data = null ) {
 464                 $comment = CommentStoreComment::newUnsavedComment( $comment, $data );
 465
 466                 # Truncate comment in a Unicode-sensitive manner
 467                 $comment->text = $this->lang->truncateForVisual( $comment->text, self::COMMENT_CHARACTER_LIMIT );
 468
 469                 if ( $this->stage > MIGRATION_OLD && !$comment->id ) {
 470                         $dbData = $comment->data;
 471                         if ( !$comment->message instanceof RawMessage ) {
 472                                 if ( $dbData === null ) {
 473                                         $dbData = [ '_null' => true ];
 474                                 }
 475                                 $dbData['_message'] = self::encodeMessage( $comment->message );
 476                         }
 477                         if ( $dbData !== null ) {
 478                                 $dbData = FormatJson::encode( (object)$dbData, false, FormatJson::ALL_OK );
 479                                 $len = strlen( $dbData );
 480                                 if ( $len > self::MAX_DATA_LENGTH ) {
 481                                         $max = self::MAX_DATA_LENGTH;
 482                                         throw new OverflowException( "Comment data is too long ($len bytes, maximum is $max)" );
 483                                 }
 484                         }
 485
 486                         $hash = self::hash( $comment->text, $dbData );
 487                         $comment->id = $dbw->selectField(
 488                                 'comment',
 489                                 'comment_id',
 490                                 [
 491                                         'comment_hash' => $hash,
 492                                         'comment_text' => $comment->text,
 493                                         'comment_data' => $dbData,
 494                                 ],
 495                                 __METHOD__
 496                         );
 497                         if ( !$comment->id ) {
 498                                 $dbw->insert(
 499                                         'comment',
 500                                         [
 501                                                 'comment_hash' => $hash,
 502                                                 'comment_text' => $comment->text,
 503                                                 'comment_data' => $dbData,
 504                                         ],
 505                                         __METHOD__
 506                                 );
 507                                 $comment->id = $dbw->insertId();
 508                         }
 509                 }
 510
 511                 return $comment;
 512         }
 513
 514         /**
 515          * Implementation for `self::insert()` and `self::insertWithTempTable()`
 516          * @param IDatabase $dbw
 517          * @param string $key A key such as "rev_comment" identifying the comment
 518          *  field being fetched.
 519          * @param string|Message|CommentStoreComment $comment
 520          * @param array|null $data
 521          * @return array [ array $fields, callable $callback ]
 522          */
 523         private function insertInternal( IDatabase $dbw, $key, $comment, $data ) {
 524                 $fields = [];
 525                 $callback = null;
 526
 527                 $comment = $this->createComment( $dbw, $comment, $data );
 528
 529                 if ( $this->stage <= MIGRATION_WRITE_BOTH ) {
 530                         $fields[$key] = $this->lang->truncateForDatabase( $comment->text, 255 );
 531                 }
 532
 533                 if ( $this->stage >= MIGRATION_WRITE_BOTH ) {
 534                         $tempTableStage = isset( $this->tempTables[$key] )
 535                                 ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 536                         if ( $tempTableStage <= MIGRATION_WRITE_BOTH ) {
 537                                 $t = $this->tempTables[$key];
 538                                 $func = __METHOD__;
 539                                 $commentId = $comment->id;
 540                                 $callback = function ( $id ) use ( $dbw, $commentId, $t, $func ) {
 541                                         $dbw->insert(
 542                                                 $t['table'],
 543                                                 [
 544                                                         $t['pk'] => $id,
 545                                                         $t['field'] => $commentId,
 546                                                 ],
 547                                                 $func
 548                                         );
 549                                 };
 550                         }
 551                         if ( $tempTableStage >= MIGRATION_WRITE_BOTH ) {
 552                                 $fields["{$key}_id"] = $comment->id;
 553                         }
 554                 }
 555
 556                 return [ $fields, $callback ];
 557         }
 558
 559         /**
 560          * Insert a comment in preparation for a row that references it
 561          *
 562          * @note It's recommended to include both the call to this method and the
 563          *  row insert in the same transaction.
 564          *
 565          * @since 1.30
 566          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 567          * @param IDatabase $dbw Database handle to insert on
 568          * @param string $key A key such as "rev_comment" identifying the comment
 569          *  field being fetched.
 570          * @param string|Message|CommentStoreComment|null $comment As for `self::createComment()`
 571          * @param array|null $data As for `self::createComment()`
 572          * @return array Fields for the insert or update
 573          */
 574         public function insert( IDatabase $dbw, $key, $comment = null, $data = null ) {
 575                 // Compat for method sig change in 1.31 (introduction of $key)
 576                 if ( $this->key !== null ) {
 577                         $data = $comment;
 578                         $comment = $key;
 579                         $key = $this->key;
 580                 }
 581                 if ( $comment === null ) {
 582                         // @codeCoverageIgnoreStart
 583                         throw new InvalidArgumentException( '$comment can not be null' );
 584                         // @codeCoverageIgnoreEnd
 585                 }
 586
 587                 $tempTableStage = isset( $this->tempTables[$key] )
 588                         ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 589                 if ( $tempTableStage < MIGRATION_WRITE_NEW ) {
 590                         throw new InvalidArgumentException( "Must use insertWithTempTable() for $key" );
 591                 }
 592
 593                 list( $fields ) = $this->insertInternal( $dbw, $key, $comment, $data );
 594                 return $fields;
 595         }
 596
 597         /**
 598          * Insert a comment in a temporary table in preparation for a row that references it
 599          *
 600          * This is currently needed for "rev_comment" and "img_description". In the
 601          * future that requirement will be removed.
 602          *
 603          * @note It's recommended to include both the call to this method and the
 604          *  row insert in the same transaction.
 605          *
 606          * @since 1.30
 607          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 608          * @param IDatabase $dbw Database handle to insert on
 609          * @param string $key A key such as "rev_comment" identifying the comment
 610          *  field being fetched.
 611          * @param string|Message|CommentStoreComment|null $comment As for `self::createComment()`
 612          * @param array|null $data As for `self::createComment()`
 613          * @return array Two values:
 614          *  - array Fields for the insert or update
 615          *  - callable Function to call when the primary key of the row being
 616          *    inserted/updated is known. Pass it that primary key.
 617          */
 618         public function insertWithTempTable( IDatabase $dbw, $key, $comment = null, $data = null ) {
 619                 // Compat for method sig change in 1.31 (introduction of $key)
 620                 if ( $this->key !== null ) {
 621                         $data = $comment;
 622                         $comment = $key;
 623                         $key = $this->getKey();
 624                 }
 625                 if ( $comment === null ) {
 626                         // @codeCoverageIgnoreStart
 627                         throw new InvalidArgumentException( '$comment can not be null' );
 628                         // @codeCoverageIgnoreEnd
 629                 }
 630
 631                 if ( !isset( $this->tempTables[$key] ) ) {
 632                         throw new InvalidArgumentException( "Must use insert() for $key" );
 633                 } elseif ( isset( $this->tempTables[$key]['deprecatedIn'] ) ) {
 634                         wfDeprecated( __METHOD__ . " for $key", $this->tempTables[$key]['deprecatedIn'] );
 635                 }
 636
 637                 list( $fields, $callback ) = $this->insertInternal( $dbw, $key, $comment, $data );
 638                 if ( !$callback ) {
 639                         $callback = function () {
 640                                 // Do nothing.
 641                         };
 642                 }
 643                 return [ $fields, $callback ];
 644         }
 645
 646         /**
 647          * Encode a Message as a PHP data structure
 648          * @param Message $msg
 649          * @return array
 650          */
 651         protected static function encodeMessage( Message $msg ) {
 652                 $key = count( $msg->getKeysToTry() ) > 1 ? $msg->getKeysToTry() : $msg->getKey();
 653                 $params = $msg->getParams();
 654                 foreach ( $params as &$param ) {
 655                         if ( $param instanceof Message ) {
 656                                 $param = [
 657                                         'message' => self::encodeMessage( $param )
 658                                 ];
 659                         }
 660                 }
 661                 array_unshift( $params, $key );
 662                 return $params;
 663         }
 664
 665         /**
 666          * Decode a message that was encoded by self::encodeMessage()
 667          * @param array $data
 668          * @return Message
 669          */
 670         protected static function decodeMessage( $data ) {
 671                 $key = array_shift( $data );
 672                 foreach ( $data as &$param ) {
 673                         if ( is_object( $param ) ) {
 674                                 $param = (array)$param;
 675                         }
 676                         if ( is_array( $param ) && count( $param ) === 1 && isset( $param['message'] ) ) {
 677                                 $param = self::decodeMessage( $param['message'] );
 678                         }
 679                 }
 680                 return new Message( $key, $data );
 681         }
 682
 683         /**
 684          * Hashing function for comment storage
 685          * @param string $text Comment text
 686          * @param string|null $data Comment data
 687          * @return int 32-bit signed integer
 688          */
 689         public static function hash( $text, $data ) {
 690                 $hash = crc32( $text ) ^ crc32( (string)$data );
 691
 692                 // 64-bit PHP returns an unsigned CRC, change it to signed for
 693                 // insertion into the database.
 694                 if ( $hash >= 0x80000000 ) {
 695                         $hash |= -1 << 32;
 696                 }
 697
 698                 return $hash;
 699         }
 700
 701 }