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                         'stage' => MIGRATION_NEW,
  74                         'deprecatedIn' => '1.32',
  75                 ],
  76         ];
  77
  78         /**
  79          * @since 1.30
  80          * @deprecated in 1.31
  81          * @var string|null
  82          */
  83         protected $key = null;
  84
  85         /**
  86          * @var int One of the MIGRATION_* constants
  87          * @todo Deprecate and remove once extensions seem unlikely to need to use
  88          *  it for migration anymore.
  89          */
  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. Always
 102          *  MIGRATION_NEW for MediaWiki core since 1.33.
 103          */
 104         public function __construct( Language $lang, $migrationStage ) {
 105                 $this->stage = $migrationStage;
 106                 $this->lang = $lang;
 107         }
 108
 109         /**
 110          * Static constructor for easier chaining
 111          * @deprecated in 1.31 Should not be constructed with a $key, use CommentStore::getStore
 112          * @param string $key A key such as "rev_comment" identifying the comment
 113          *  field being fetched.
 114          * @return CommentStore
 115          */
 116         public static function newKey( $key ) {
 117                 wfDeprecated( __METHOD__, '1.31' );
 118                 $store = new CommentStore(
 119                         MediaWikiServices::getInstance()->getContentLanguage(), MIGRATION_NEW
 120                 );
 121                 $store->key = $key;
 122                 return $store;
 123         }
 124
 125         /**
 126          * @since 1.31
 127          * @deprecated in 1.31 Use DI to inject a CommentStore instance into your class.
 128          * @return CommentStore
 129          */
 130         public static function getStore() {
 131                 return MediaWikiServices::getInstance()->getCommentStore();
 132         }
 133
 134         /**
 135          * Compat method allowing use of self::newKey until removed.
 136          * @param string|null $methodKey
 137          * @throws InvalidArgumentException
 138          * @return string
 139          */
 140         private function getKey( $methodKey = null ) {
 141                 $key = $this->key ?? $methodKey;
 142                 if ( $key === null ) {
 143                         // @codeCoverageIgnoreStart
 144                         throw new InvalidArgumentException( '$key should not be null' );
 145                         // @codeCoverageIgnoreEnd
 146                 }
 147                 return $key;
 148         }
 149
 150         /**
 151          * Get SELECT fields for the comment key
 152          *
 153          * Each resulting row should be passed to `self::getCommentLegacy()` to get the
 154          * actual comment.
 155          *
 156          * @note Use of this method may require a subsequent database query to
 157          *  actually fetch the comment. If possible, use `self::getJoin()` instead.
 158          *
 159          * @since 1.30
 160          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 161          * @param string|null $key A key such as "rev_comment" identifying the comment
 162          *  field being fetched.
 163          * @return string[] to include in the `$vars` to `IDatabase->select()`. All
 164          *  fields are aliased, so `+` is safe to use.
 165          */
 166         public function getFields( $key = null ) {
 167                 $key = $this->getKey( $key );
 168                 $fields = [];
 169                 if ( $this->stage === MIGRATION_OLD ) {
 170                         $fields["{$key}_text"] = $key;
 171                         $fields["{$key}_data"] = 'NULL';
 172                         $fields["{$key}_cid"] = 'NULL';
 173                 } else {
 174                         if ( $this->stage < MIGRATION_NEW ) {
 175                                 $fields["{$key}_old"] = $key;
 176                         }
 177
 178                         $tempTableStage = isset( $this->tempTables[$key] )
 179                                 ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 180                         if ( $tempTableStage < MIGRATION_NEW ) {
 181                                 $fields["{$key}_pk"] = $this->tempTables[$key]['joinPK'];
 182                         }
 183                         if ( $tempTableStage > MIGRATION_OLD ) {
 184                                 $fields["{$key}_id"] = "{$key}_id";
 185                         }
 186                 }
 187                 return $fields;
 188         }
 189
 190         /**
 191          * Get SELECT fields and joins for the comment key
 192          *
 193          * Each resulting row should be passed to `self::getComment()` to get the
 194          * actual comment.
 195          *
 196          * @since 1.30
 197          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 198          * @param string|null $key A key such as "rev_comment" identifying the comment
 199          *  field being fetched.
 200          * @return array[] With three keys:
 201          *   - tables: (string[]) to include in the `$table` to `IDatabase->select()`
 202          *   - fields: (string[]) to include in the `$vars` to `IDatabase->select()`
 203          *   - joins: (array) to include in the `$join_conds` to `IDatabase->select()`
 204          *  All tables, fields, and joins are aliased, so `+` is safe to use.
 205          * @phan-return array{tables:string[],fields:string[],joins:array}
 206          */
 207         public function getJoin( $key = null ) {
 208                 $key = $this->getKey( $key );
 209                 if ( !array_key_exists( $key, $this->joinCache ) ) {
 210                         $tables = [];
 211                         $fields = [];
 212                         $joins = [];
 213
 214                         if ( $this->stage === MIGRATION_OLD ) {
 215                                 $fields["{$key}_text"] = $key;
 216                                 $fields["{$key}_data"] = 'NULL';
 217                                 $fields["{$key}_cid"] = 'NULL';
 218                         } else {
 219                                 $join = $this->stage === MIGRATION_NEW ? 'JOIN' : 'LEFT JOIN';
 220
 221                                 $tempTableStage = isset( $this->tempTables[$key] )
 222                                         ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 223                                 if ( $tempTableStage < MIGRATION_NEW ) {
 224                                         $t = $this->tempTables[$key];
 225                                         $alias = "temp_$key";
 226                                         $tables[$alias] = $t['table'];
 227                                         $joins[$alias] = [ $join, "{$alias}.{$t['pk']} = {$t['joinPK']}" ];
 228                                         if ( $tempTableStage === MIGRATION_OLD ) {
 229                                                 $joinField = "{$alias}.{$t['field']}";
 230                                         } else {
 231                                                 // Nothing hits this code path for now, but will in the future when we set
 232                                                 // $this->tempTables['rev_comment']['stage'] to MIGRATION_WRITE_NEW while
 233                                                 // merging revision_comment_temp into revision.
 234                                                 // @codeCoverageIgnoreStart
 235                                                 $joins[$alias][0] = 'LEFT JOIN';
 236                                                 $joinField = "(CASE WHEN {$key}_id != 0 THEN {$key}_id ELSE {$alias}.{$t['field']} END)";
 237                                                 throw new LogicException( 'Nothing should reach this code path at this time' );
 238                                                 // @codeCoverageIgnoreEnd
 239                                         }
 240                                 } else {
 241                                         $joinField = "{$key}_id";
 242                                 }
 243
 244                                 $alias = "comment_$key";
 245                                 $tables[$alias] = 'comment';
 246                                 $joins[$alias] = [ $join, "{$alias}.comment_id = {$joinField}" ];
 247
 248                                 if ( $this->stage === MIGRATION_NEW ) {
 249                                         $fields["{$key}_text"] = "{$alias}.comment_text";
 250                                 } else {
 251                                         $fields["{$key}_text"] = "COALESCE( {$alias}.comment_text, $key )";
 252                                 }
 253                                 $fields["{$key}_data"] = "{$alias}.comment_data";
 254                                 $fields["{$key}_cid"] = "{$alias}.comment_id";
 255                         }
 256
 257                         $this->joinCache[$key] = [
 258                                 'tables' => $tables,
 259                                 'fields' => $fields,
 260                                 'joins' => $joins,
 261                         ];
 262                 }
 263
 264                 return $this->joinCache[$key];
 265         }
 266
 267         /**
 268          * Extract the comment from a row
 269          *
 270          * Shared implementation for getComment() and getCommentLegacy()
 271          *
 272          * @param IDatabase|null $db Database handle for getCommentLegacy(), or null for getComment()
 273          * @param string $key A key such as "rev_comment" identifying the comment
 274          *  field being fetched.
 275          * @param object|array $row
 276          * @param bool $fallback
 277          * @return CommentStoreComment
 278          */
 279         private function getCommentInternal( IDatabase $db = null, $key, $row, $fallback = false ) {
 280                 $row = (array)$row;
 281                 if ( array_key_exists( "{$key}_text", $row ) && array_key_exists( "{$key}_data", $row ) ) {
 282                         $cid = $row["{$key}_cid"] ?? null;
 283                         $text = $row["{$key}_text"];
 284                         $data = $row["{$key}_data"];
 285                 } elseif ( $this->stage === MIGRATION_OLD ) {
 286                         $cid = null;
 287                         if ( $fallback && isset( $row[$key] ) ) {
 288                                 wfLogWarning( "Using deprecated fallback handling for comment $key" );
 289                                 $text = $row[$key];
 290                         } else {
 291                                 wfLogWarning( "Missing {$key}_text and {$key}_data fields in row with MIGRATION_OLD" );
 292                                 $text = '';
 293                         }
 294                         $data = null;
 295                 } else {
 296                         $tempTableStage = isset( $this->tempTables[$key] )
 297                                 ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 298                         $row2 = null;
 299                         if ( $tempTableStage > MIGRATION_OLD && array_key_exists( "{$key}_id", $row ) ) {
 300                                 if ( !$db ) {
 301                                         throw new InvalidArgumentException(
 302                                                 "\$row does not contain fields needed for comment $key and getComment(), but "
 303                                                 . "does have fields for getCommentLegacy()"
 304                                         );
 305                                 }
 306                                 $id = $row["{$key}_id"];
 307                                 $row2 = $db->selectRow(
 308                                         'comment',
 309                                         [ 'comment_id', 'comment_text', 'comment_data' ],
 310                                         [ 'comment_id' => $id ],
 311                                         __METHOD__
 312                                 );
 313                         }
 314                         if ( !$row2 && $tempTableStage < MIGRATION_NEW && array_key_exists( "{$key}_pk", $row ) ) {
 315                                 if ( !$db ) {
 316                                         throw new InvalidArgumentException(
 317                                                 "\$row does not contain fields needed for comment $key and getComment(), but "
 318                                                 . "does have fields for getCommentLegacy()"
 319                                         );
 320                                 }
 321                                 $t = $this->tempTables[$key];
 322                                 $id = $row["{$key}_pk"];
 323                                 $row2 = $db->selectRow(
 324                                         [ $t['table'], 'comment' ],
 325                                         [ 'comment_id', 'comment_text', 'comment_data' ],
 326                                         [ $t['pk'] => $id ],
 327                                         __METHOD__,
 328                                         [],
 329                                         [ 'comment' => [ 'JOIN', [ "comment_id = {$t['field']}" ] ] ]
 330                                 );
 331                         }
 332                         if ( $row2 === null && $fallback && isset( $row[$key] ) ) {
 333                                 wfLogWarning( "Using deprecated fallback handling for comment $key" );
 334                                 $row2 = (object)[ 'comment_text' => $row[$key], 'comment_data' => null ];
 335                         }
 336                         if ( $row2 === null ) {
 337                                 throw new InvalidArgumentException( "\$row does not contain fields needed for comment $key" );
 338                         }
 339
 340                         if ( $row2 ) {
 341                                 $cid = $row2->comment_id;
 342                                 $text = $row2->comment_text;
 343                                 $data = $row2->comment_data;
 344                         } elseif ( $this->stage < MIGRATION_NEW && array_key_exists( "{$key}_old", $row ) ) {
 345                                 $cid = null;
 346                                 $text = $row["{$key}_old"];
 347                                 $data = null;
 348                         } else {
 349                                 // @codeCoverageIgnoreStart
 350                                 wfLogWarning( "Missing comment row for $key, id=$id" );
 351                                 $cid = null;
 352                                 $text = '';
 353                                 $data = null;
 354                                 // @codeCoverageIgnoreEnd
 355                         }
 356                 }
 357
 358                 $msg = null;
 359                 if ( $data !== null ) {
 360                         $data = FormatJson::decode( $data, true );
 361                         if ( !is_array( $data ) ) {
 362                                 // @codeCoverageIgnoreStart
 363                                 wfLogWarning( "Invalid JSON object in comment: $data" );
 364                                 $data = null;
 365                                 // @codeCoverageIgnoreEnd
 366                         } else {
 367                                 if ( isset( $data['_message'] ) ) {
 368                                         $msg = self::decodeMessage( $data['_message'] )
 369                                                 ->setInterfaceMessageFlag( true );
 370                                 }
 371                                 if ( !empty( $data['_null'] ) ) {
 372                                         $data = null;
 373                                 } else {
 374                                         foreach ( $data as $k => $v ) {
 375                                                 if ( substr( $k, 0, 1 ) === '_' ) {
 376                                                         unset( $data[$k] );
 377                                                 }
 378                                         }
 379                                 }
 380                         }
 381                 }
 382
 383                 return new CommentStoreComment( $cid, $text, $msg, $data );
 384         }
 385
 386         /**
 387          * Extract the comment from a row
 388          *
 389          * Use `self::getJoin()` to ensure the row contains the needed data.
 390          *
 391          * If you need to fake a comment in a row for some reason, set fields
 392          * `{$key}_text` (string) and `{$key}_data` (JSON string or null).
 393          *
 394          * @since 1.30
 395          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 396          * @param string $key A key such as "rev_comment" identifying the comment
 397          *  field being fetched.
 398          * @param object|array|null $row Result row.
 399          * @param bool $fallback If true, fall back as well as possible instead of throwing an exception.
 400          * @return CommentStoreComment
 401          */
 402         public function getComment( $key, $row = null, $fallback = false ) {
 403                 // Compat for method sig change in 1.31 (introduction of $key)
 404                 if ( $this->key !== null ) {
 405                         $fallback = $row;
 406                         $row = $key;
 407                         $key = $this->getKey();
 408                 }
 409                 if ( $row === null ) {
 410                         // @codeCoverageIgnoreStart
 411                         throw new InvalidArgumentException( '$row must not be null' );
 412                         // @codeCoverageIgnoreEnd
 413                 }
 414                 return $this->getCommentInternal( null, $key, $row, $fallback );
 415         }
 416
 417         /**
 418          * Extract the comment from a row, with legacy lookups.
 419          *
 420          * If `$row` might have been generated using `self::getFields()` rather
 421          * than `self::getJoin()`, use this. Prefer `self::getComment()` if you
 422          * know callers used `self::getJoin()` for the row fetch.
 423          *
 424          * If you need to fake a comment in a row for some reason, set fields
 425          * `{$key}_text` (string) and `{$key}_data` (JSON string or null).
 426          *
 427          * @since 1.30
 428          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 429          * @param IDatabase $db Database handle to use for lookup
 430          * @param string $key A key such as "rev_comment" identifying the comment
 431          *  field being fetched.
 432          * @param object|array|null $row Result row.
 433          * @param bool $fallback If true, fall back as well as possible instead of throwing an exception.
 434          * @return CommentStoreComment
 435          */
 436         public function getCommentLegacy( IDatabase $db, $key, $row = null, $fallback = false ) {
 437                 // Compat for method sig change in 1.31 (introduction of $key)
 438                 if ( $this->key !== null ) {
 439                         $fallback = $row;
 440                         $row = $key;
 441                         $key = $this->getKey();
 442                 }
 443                 if ( $row === null ) {
 444                         // @codeCoverageIgnoreStart
 445                         throw new InvalidArgumentException( '$row must not be null' );
 446                         // @codeCoverageIgnoreEnd
 447                 }
 448                 return $this->getCommentInternal( $db, $key, $row, $fallback );
 449         }
 450
 451         /**
 452          * Create a new CommentStoreComment, inserting it into the database if necessary
 453          *
 454          * If a comment is going to be passed to `self::insert()` or the like
 455          * multiple times, it will be more efficient to pass a CommentStoreComment
 456          * once rather than making `self::insert()` do it every time through.
 457          *
 458          * @note When passing a CommentStoreComment, this may set `$comment->id` if
 459          *  it's not already set. If `$comment->id` is already set, it will not be
 460          *  verified that the specified comment actually exists or that it
 461          *  corresponds to the comment text, message, and/or data in the
 462          *  CommentStoreComment.
 463          * @param IDatabase $dbw Database handle to insert on. Unused if `$comment`
 464          *  is a CommentStoreComment and `$comment->id` is set.
 465          * @param string|Message|CommentStoreComment $comment Comment text or Message object, or
 466          *  a CommentStoreComment.
 467          * @param array|null $data Structured data to store. Keys beginning with '_' are reserved.
 468          *  Ignored if $comment is a CommentStoreComment.
 469          * @return CommentStoreComment
 470          */
 471         public function createComment( IDatabase $dbw, $comment, array $data = null ) {
 472                 $comment = CommentStoreComment::newUnsavedComment( $comment, $data );
 473
 474                 # Truncate comment in a Unicode-sensitive manner
 475                 $comment->text = $this->lang->truncateForVisual( $comment->text, self::COMMENT_CHARACTER_LIMIT );
 476
 477                 if ( $this->stage > MIGRATION_OLD && !$comment->id ) {
 478                         $dbData = $comment->data;
 479                         if ( !$comment->message instanceof RawMessage ) {
 480                                 if ( $dbData === null ) {
 481                                         $dbData = [ '_null' => true ];
 482                                 }
 483                                 $dbData['_message'] = self::encodeMessage( $comment->message );
 484                         }
 485                         if ( $dbData !== null ) {
 486                                 $dbData = FormatJson::encode( (object)$dbData, false, FormatJson::ALL_OK );
 487                                 $len = strlen( $dbData );
 488                                 if ( $len > self::MAX_DATA_LENGTH ) {
 489                                         $max = self::MAX_DATA_LENGTH;
 490                                         throw new OverflowException( "Comment data is too long ($len bytes, maximum is $max)" );
 491                                 }
 492                         }
 493
 494                         $hash = self::hash( $comment->text, $dbData );
 495                         $comment->id = $dbw->selectField(
 496                                 'comment',
 497                                 'comment_id',
 498                                 [
 499                                         'comment_hash' => $hash,
 500                                         'comment_text' => $comment->text,
 501                                         'comment_data' => $dbData,
 502                                 ],
 503                                 __METHOD__
 504                         );
 505                         if ( !$comment->id ) {
 506                                 $dbw->insert(
 507                                         'comment',
 508                                         [
 509                                                 'comment_hash' => $hash,
 510                                                 'comment_text' => $comment->text,
 511                                                 'comment_data' => $dbData,
 512                                         ],
 513                                         __METHOD__
 514                                 );
 515                                 $comment->id = $dbw->insertId();
 516                         }
 517                 }
 518
 519                 return $comment;
 520         }
 521
 522         /**
 523          * Implementation for `self::insert()` and `self::insertWithTempTable()`
 524          * @param IDatabase $dbw
 525          * @param string $key A key such as "rev_comment" identifying the comment
 526          *  field being fetched.
 527          * @param string|Message|CommentStoreComment $comment
 528          * @param array|null $data
 529          * @return array [ array $fields, callable $callback ]
 530          */
 531         private function insertInternal( IDatabase $dbw, $key, $comment, $data ) {
 532                 $fields = [];
 533                 $callback = null;
 534
 535                 $comment = $this->createComment( $dbw, $comment, $data );
 536
 537                 if ( $this->stage <= MIGRATION_WRITE_BOTH ) {
 538                         $fields[$key] = $this->lang->truncateForDatabase( $comment->text, 255 );
 539                 }
 540
 541                 if ( $this->stage >= MIGRATION_WRITE_BOTH ) {
 542                         $tempTableStage = isset( $this->tempTables[$key] )
 543                                 ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 544                         if ( $tempTableStage <= MIGRATION_WRITE_BOTH ) {
 545                                 $t = $this->tempTables[$key];
 546                                 $func = __METHOD__;
 547                                 $commentId = $comment->id;
 548                                 $callback = function ( $id ) use ( $dbw, $commentId, $t, $func ) {
 549                                         $dbw->insert(
 550                                                 $t['table'],
 551                                                 [
 552                                                         $t['pk'] => $id,
 553                                                         $t['field'] => $commentId,
 554                                                 ],
 555                                                 $func
 556                                         );
 557                                 };
 558                         }
 559                         if ( $tempTableStage >= MIGRATION_WRITE_BOTH ) {
 560                                 $fields["{$key}_id"] = $comment->id;
 561                         }
 562                 }
 563
 564                 return [ $fields, $callback ];
 565         }
 566
 567         /**
 568          * Insert a comment in preparation for a row that references it
 569          *
 570          * @note It's recommended to include both the call to this method and the
 571          *  row insert in the same transaction.
 572          *
 573          * @since 1.30
 574          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 575          * @param IDatabase $dbw Database handle to insert on
 576          * @param string $key A key such as "rev_comment" identifying the comment
 577          *  field being fetched.
 578          * @param string|Message|CommentStoreComment|null $comment As for `self::createComment()`
 579          * @param array|null $data As for `self::createComment()`
 580          * @return array Fields for the insert or update
 581          */
 582         public function insert( IDatabase $dbw, $key, $comment = null, $data = null ) {
 583                 // Compat for method sig change in 1.31 (introduction of $key)
 584                 if ( $this->key !== null ) {
 585                         $data = $comment;
 586                         $comment = $key;
 587                         $key = $this->key;
 588                 }
 589                 if ( $comment === null ) {
 590                         // @codeCoverageIgnoreStart
 591                         throw new InvalidArgumentException( '$comment can not be null' );
 592                         // @codeCoverageIgnoreEnd
 593                 }
 594
 595                 $tempTableStage = isset( $this->tempTables[$key] )
 596                         ? $this->tempTables[$key]['stage'] : MIGRATION_NEW;
 597                 if ( $tempTableStage < MIGRATION_WRITE_NEW ) {
 598                         throw new InvalidArgumentException( "Must use insertWithTempTable() for $key" );
 599                 }
 600
 601                 list( $fields ) = $this->insertInternal( $dbw, $key, $comment, $data );
 602                 return $fields;
 603         }
 604
 605         /**
 606          * Insert a comment in a temporary table in preparation for a row that references it
 607          *
 608          * This is currently needed for "rev_comment" and "img_description". In the
 609          * future that requirement will be removed.
 610          *
 611          * @note It's recommended to include both the call to this method and the
 612          *  row insert in the same transaction.
 613          *
 614          * @since 1.30
 615          * @since 1.31 Method signature changed, $key parameter added (with deprecated back compat)
 616          * @param IDatabase $dbw Database handle to insert on
 617          * @param string $key A key such as "rev_comment" identifying the comment
 618          *  field being fetched.
 619          * @param string|Message|CommentStoreComment|null $comment As for `self::createComment()`
 620          * @param array|null $data As for `self::createComment()`
 621          * @return array Two values:
 622          *  - array Fields for the insert or update
 623          *  - callable Function to call when the primary key of the row being
 624          *    inserted/updated is known. Pass it that primary key.
 625          */
 626         public function insertWithTempTable( IDatabase $dbw, $key, $comment = null, $data = null ) {
 627                 // Compat for method sig change in 1.31 (introduction of $key)
 628                 if ( $this->key !== null ) {
 629                         $data = $comment;
 630                         $comment = $key;
 631                         $key = $this->getKey();
 632                 }
 633                 if ( $comment === null ) {
 634                         // @codeCoverageIgnoreStart
 635                         throw new InvalidArgumentException( '$comment can not be null' );
 636                         // @codeCoverageIgnoreEnd
 637                 }
 638
 639                 if ( !isset( $this->tempTables[$key] ) ) {
 640                         throw new InvalidArgumentException( "Must use insert() for $key" );
 641                 } elseif ( isset( $this->tempTables[$key]['deprecatedIn'] ) ) {
 642                         wfDeprecated( __METHOD__ . " for $key", $this->tempTables[$key]['deprecatedIn'] );
 643                 }
 644
 645                 list( $fields, $callback ) = $this->insertInternal( $dbw, $key, $comment, $data );
 646                 if ( !$callback ) {
 647                         $callback = function () {
 648                                 // Do nothing.
 649                         };
 650                 }
 651                 return [ $fields, $callback ];
 652         }
 653
 654         /**
 655          * Encode a Message as a PHP data structure
 656          * @param Message $msg
 657          * @return array
 658          */
 659         protected static function encodeMessage( Message $msg ) {
 660                 $key = count( $msg->getKeysToTry() ) > 1 ? $msg->getKeysToTry() : $msg->getKey();
 661                 $params = $msg->getParams();
 662                 foreach ( $params as &$param ) {
 663                         if ( $param instanceof Message ) {
 664                                 $param = [
 665                                         'message' => self::encodeMessage( $param )
 666                                 ];
 667                         }
 668                 }
 669                 array_unshift( $params, $key );
 670                 return $params;
 671         }
 672
 673         /**
 674          * Decode a message that was encoded by self::encodeMessage()
 675          * @param array $data
 676          * @return Message
 677          */
 678         protected static function decodeMessage( $data ) {
 679                 $key = array_shift( $data );
 680                 foreach ( $data as &$param ) {
 681                         if ( is_object( $param ) ) {
 682                                 $param = (array)$param;
 683                         }
 684                         if ( is_array( $param ) && count( $param ) === 1 && isset( $param['message'] ) ) {
 685                                 $param = self::decodeMessage( $param['message'] );
 686                         }
 687                 }
 688                 return new Message( $key, $data );
 689         }
 690
 691         /**
 692          * Hashing function for comment storage
 693          * @param string $text Comment text
 694          * @param string|null $data Comment data
 695          * @return int 32-bit signed integer
 696          */
 697         public static function hash( $text, $data ) {
 698                 $hash = crc32( $text ) ^ crc32( (string)$data );
 699
 700                 // 64-bit PHP returns an unsigned CRC, change it to signed for
 701                 // insertion into the database.
 702                 if ( $hash >= 0x80000000 ) {
 703                         $hash |= -1 << 32;
 704                 }
 705
 706                 return $hash;
 707         }
 708
 709 }