maintenance/storage/fixBug20757.php

   1 <?php
   2 /**
   3  * Script to fix bug 20757.
   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  * @ingroup Maintenance ExternalStorage
  22  */
  23
  24 require_once __DIR__ . '/../Maintenance.php';
  25
  26 /**
  27  * Maintenance script to fix bug 20757.
  28  *
  29  * @ingroup Maintenance ExternalStorage
  30  */
  31 class FixBug20757 extends Maintenance {
  32         public $batchSize = 10000;
  33         public $mapCache = [];
  34         public $mapCacheSize = 0;
  35         public $maxMapCacheSize = 1000000;
  36
  37         function __construct() {
  38                 parent::__construct();
  39                 $this->addDescription( 'Script to fix bug 20757 assuming that blob_tracking is intact' );
  40                 $this->addOption( 'dry-run', 'Report only' );
  41                 $this->addOption( 'start', 'old_id to start at', false, true );
  42         }
  43
  44         function execute() {
  45                 $dbr = $this->getDB( DB_SLAVE );
  46                 $dbw = $this->getDB( DB_MASTER );
  47
  48                 $dryRun = $this->getOption( 'dry-run' );
  49                 if ( $dryRun ) {
  50                         print "Dry run only.\n";
  51                 }
  52
  53                 $startId = $this->getOption( 'start', 0 );
  54                 $numGood = 0;
  55                 $numFixed = 0;
  56                 $numBad = 0;
  57
  58                 $totalRevs = $dbr->selectField( 'text', 'MAX(old_id)', false, __METHOD__ );
  59
  60                 if ( $dbr->getType() == 'mysql' ) {
  61                         // In MySQL 4.1+, the binary field old_text has a non-working LOWER() function
  62                         $lowerLeft = 'LOWER(CONVERT(LEFT(old_text,22) USING latin1))';
  63                 }
  64
  65                 while ( true ) {
  66                         print "ID: $startId / $totalRevs\r";
  67
  68                         $res = $dbr->select(
  69                                 'text',
  70                                 [ 'old_id', 'old_flags', 'old_text' ],
  71                                 [
  72                                         'old_id > ' . intval( $startId ),
  73                                         'old_flags LIKE \'%object%\' AND old_flags NOT LIKE \'%external%\'',
  74                                         "$lowerLeft = 'o:15:\"historyblobstub\"'",
  75                                 ],
  76                                 __METHOD__,
  77                                 [
  78                                         'ORDER BY' => 'old_id',
  79                                         'LIMIT' => $this->batchSize,
  80                                 ]
  81                         );
  82
  83                         if ( !$res->numRows() ) {
  84                                 break;
  85                         }
  86
  87                         $secondaryIds = [];
  88                         $stubs = [];
  89
  90                         foreach ( $res as $row ) {
  91                                 $startId = $row->old_id;
  92
  93                                 // Basic sanity checks
  94                                 $obj = unserialize( $row->old_text );
  95                                 if ( $obj === false ) {
  96                                         print "{$row->old_id}: unrecoverable: cannot unserialize\n";
  97                                         ++$numBad;
  98                                         continue;
  99                                 }
 100
 101                                 if ( !is_object( $obj ) ) {
 102                                         print "{$row->old_id}: unrecoverable: unserialized to type " .
 103                                                 gettype( $obj ) . ", possible double-serialization\n";
 104                                         ++$numBad;
 105                                         continue;
 106                                 }
 107
 108                                 if ( strtolower( get_class( $obj ) ) !== 'historyblobstub' ) {
 109                                         print "{$row->old_id}: unrecoverable: unexpected object class " .
 110                                                 get_class( $obj ) . "\n";
 111                                         ++$numBad;
 112                                         continue;
 113                                 }
 114
 115                                 // Process flags
 116                                 $flags = explode( ',', $row->old_flags );
 117                                 if ( in_array( 'utf-8', $flags ) || in_array( 'utf8', $flags ) ) {
 118                                         $legacyEncoding = false;
 119                                 } else {
 120                                         $legacyEncoding = true;
 121                                 }
 122
 123                                 // Queue the stub for future batch processing
 124                                 $id = intval( $obj->mOldId );
 125                                 $secondaryIds[] = $id;
 126                                 $stubs[$row->old_id] = [
 127                                         'legacyEncoding' => $legacyEncoding,
 128                                         'secondaryId' => $id,
 129                                         'hash' => $obj->mHash,
 130                                 ];
 131                         }
 132
 133                         $secondaryIds = array_unique( $secondaryIds );
 134
 135                         if ( !count( $secondaryIds ) ) {
 136                                 continue;
 137                         }
 138
 139                         // Run the batch query on blob_tracking
 140                         $res = $dbr->select(
 141                                 'blob_tracking',
 142                                 '*',
 143                                 [
 144                                         'bt_text_id' => $secondaryIds,
 145                                 ],
 146                                 __METHOD__
 147                         );
 148                         $trackedBlobs = [];
 149                         foreach ( $res as $row ) {
 150                                 $trackedBlobs[$row->bt_text_id] = $row;
 151                         }
 152
 153                         // Process the stubs
 154                         foreach ( $stubs as $primaryId => $stub ) {
 155                                 $secondaryId = $stub['secondaryId'];
 156                                 if ( !isset( $trackedBlobs[$secondaryId] ) ) {
 157                                         // No tracked blob. Work out what went wrong
 158                                         $secondaryRow = $dbr->selectRow(
 159                                                 'text',
 160                                                 [ 'old_flags', 'old_text' ],
 161                                                 [ 'old_id' => $secondaryId ],
 162                                                 __METHOD__
 163                                         );
 164                                         if ( !$secondaryRow ) {
 165                                                 print "$primaryId: unrecoverable: secondary row is missing\n";
 166                                                 ++$numBad;
 167                                         } elseif ( $this->isUnbrokenStub( $stub, $secondaryRow ) ) {
 168                                                 // Not broken yet, and not in the tracked clusters so it won't get
 169                                                 // broken by the current RCT run.
 170                                                 ++$numGood;
 171                                         } elseif ( strpos( $secondaryRow->old_flags, 'external' ) !== false ) {
 172                                                 print "$primaryId: unrecoverable: secondary gone to {$secondaryRow->old_text}\n";
 173                                                 ++$numBad;
 174                                         } else {
 175                                                 print "$primaryId: unrecoverable: miscellaneous corruption of secondary row\n";
 176                                                 ++$numBad;
 177                                         }
 178                                         unset( $stubs[$primaryId] );
 179                                         continue;
 180                                 }
 181                                 $trackRow = $trackedBlobs[$secondaryId];
 182
 183                                 // Check that the specified text really is available in the tracked source row
 184                                 $url = "DB://{$trackRow->bt_cluster}/{$trackRow->bt_blob_id}/{$stub['hash']}";
 185                                 $text = ExternalStore::fetchFromURL( $url );
 186                                 if ( $text === false ) {
 187                                         print "$primaryId: unrecoverable: source text missing\n";
 188                                         ++$numBad;
 189                                         unset( $stubs[$primaryId] );
 190                                         continue;
 191                                 }
 192                                 if ( md5( $text ) !== $stub['hash'] ) {
 193                                         print "$primaryId: unrecoverable: content hashes do not match\n";
 194                                         ++$numBad;
 195                                         unset( $stubs[$primaryId] );
 196                                         continue;
 197                                 }
 198
 199                                 // Find the page_id and rev_id
 200                                 // The page is probably the same as the page of the secondary row
 201                                 $pageId = intval( $trackRow->bt_page );
 202                                 if ( !$pageId ) {
 203                                         $revId = $pageId = 0;
 204                                 } else {
 205                                         $revId = $this->findTextIdInPage( $pageId, $primaryId );
 206                                         if ( !$revId ) {
 207                                                 // Actually an orphan
 208                                                 $pageId = $revId = 0;
 209                                         }
 210                                 }
 211
 212                                 $newFlags = $stub['legacyEncoding'] ? 'external' : 'external,utf-8';
 213
 214                                 if ( !$dryRun ) {
 215                                         // Reset the text row to point to the original copy
 216                                         $this->beginTransaction( $dbw, __METHOD__ );
 217                                         $dbw->update(
 218                                                 'text',
 219                                                 // SET
 220                                                 [
 221                                                         'old_flags' => $newFlags,
 222                                                         'old_text' => $url
 223                                                 ],
 224                                                 // WHERE
 225                                                 [ 'old_id' => $primaryId ],
 226                                                 __METHOD__
 227                                         );
 228
 229                                         // Add a blob_tracking row so that the new reference can be recompressed
 230                                         // without needing to run trackBlobs.php again
 231                                         $dbw->insert( 'blob_tracking',
 232                                                 [
 233                                                         'bt_page' => $pageId,
 234                                                         'bt_rev_id' => $revId,
 235                                                         'bt_text_id' => $primaryId,
 236                                                         'bt_cluster' => $trackRow->bt_cluster,
 237                                                         'bt_blob_id' => $trackRow->bt_blob_id,
 238                                                         'bt_cgz_hash' => $stub['hash'],
 239                                                         'bt_new_url' => null,
 240                                                         'bt_moved' => 0,
 241                                                 ],
 242                                                 __METHOD__
 243                                         );
 244                                         $this->commitTransaction( $dbw, __METHOD__ );
 245                                         $this->waitForSlaves();
 246                                 }
 247
 248                                 print "$primaryId: resolved to $url\n";
 249                                 ++$numFixed;
 250                         }
 251                 }
 252
 253                 print "\n";
 254                 print "Fixed: $numFixed\n";
 255                 print "Unrecoverable: $numBad\n";
 256                 print "Good stubs: $numGood\n";
 257         }
 258
 259         function waitForSlaves() {
 260                 static $iteration = 0;
 261                 ++$iteration;
 262                 if ( ++$iteration > 50 == 0 ) {
 263                         wfWaitForSlaves();
 264                         $iteration = 0;
 265                 }
 266         }
 267
 268         function findTextIdInPage( $pageId, $textId ) {
 269                 $ids = $this->getRevTextMap( $pageId );
 270                 if ( !isset( $ids[$textId] ) ) {
 271                         return null;
 272                 } else {
 273                         return $ids[$textId];
 274                 }
 275         }
 276
 277         function getRevTextMap( $pageId ) {
 278                 if ( !isset( $this->mapCache[$pageId] ) ) {
 279                         // Limit cache size
 280                         while ( $this->mapCacheSize > $this->maxMapCacheSize ) {
 281                                 $key = key( $this->mapCache );
 282                                 $this->mapCacheSize -= count( $this->mapCache[$key] );
 283                                 unset( $this->mapCache[$key] );
 284                         }
 285
 286                         $dbr = $this->getDB( DB_SLAVE );
 287                         $map = [];
 288                         $res = $dbr->select( 'revision',
 289                                 [ 'rev_id', 'rev_text_id' ],
 290                                 [ 'rev_page' => $pageId ],
 291                                 __METHOD__
 292                         );
 293                         foreach ( $res as $row ) {
 294                                 $map[$row->rev_text_id] = $row->rev_id;
 295                         }
 296                         $this->mapCache[$pageId] = $map;
 297                         $this->mapCacheSize += count( $map );
 298                 }
 299
 300                 return $this->mapCache[$pageId];
 301         }
 302
 303         /**
 304          * This is based on part of HistoryBlobStub::getText().
 305          * Determine if the text can be retrieved from the row in the normal way.
 306          * @param array $stub
 307          * @param stdClass $secondaryRow
 308          * @return bool
 309          */
 310         function isUnbrokenStub( $stub, $secondaryRow ) {
 311                 $flags = explode( ',', $secondaryRow->old_flags );
 312                 $text = $secondaryRow->old_text;
 313                 if ( in_array( 'external', $flags ) ) {
 314                         $url = $text;
 315                         MediaWiki\suppressWarnings();
 316                         list( /* $proto */, $path ) = explode( '://', $url, 2 );
 317                         MediaWiki\restoreWarnings();
 318
 319                         if ( $path == "" ) {
 320                                 return false;
 321                         }
 322                         $text = ExternalStore::fetchFromURL( $url );
 323                 }
 324                 if ( !in_array( 'object', $flags ) ) {
 325                         return false;
 326                 }
 327
 328                 if ( in_array( 'gzip', $flags ) ) {
 329                         $obj = unserialize( gzinflate( $text ) );
 330                 } else {
 331                         $obj = unserialize( $text );
 332                 }
 333
 334                 if ( !is_object( $obj ) ) {
 335                         // Correct for old double-serialization bug.
 336                         $obj = unserialize( $obj );
 337                 }
 338
 339                 if ( !is_object( $obj ) ) {
 340                         return false;
 341                 }
 342
 343                 $obj->uncompress();
 344                 $text = $obj->getItem( $stub['hash'] );
 345
 346                 return $text !== false;
 347         }
 348 }
 349
 350 $maintClass = 'FixBug20757';
 351 require_once RUN_MAINTENANCE_IF_MAIN;