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