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