Remove Revision::getRevisionText and gated pre-MCR schema access

- fixT22757.php appears to have been written for T22757 which has been
resolved, I assume it can be removed.

- compressOld.php - rev_text_id access is gated on MCRSchemaMigrationStage
READ_OLD. IT's safe to use the old_text and old_flags directly as we
select for them. Also the query ensures external blobs are not selected,
so we can use decompressData instead of Revision::getRevisionText.
Tested locally.

- recompressTracked.php uses a temporary table for tracking the blobs.
Table is populated by trackBlobs which explicitly queries for old_id,
so using it directly in recompressTracked is ok.
Tested locally.

- checkStorage.php the affected code attempts to fix broken revisions
from a dump, however, it looks like it doesn't work - the code expects
revision IDs as input, however it receives an array of text table old_id
values. Untested.

Bug: T198343
Change-Id: I753019565c15d270c831c995c07c7f1aad887cb6

4 files changed, 38 insertions, 341 deletions

diff --git a/maintenance/storage/checkStorage.php b/maintenance/storage/checkStorage.php
index 37625cf2f0a3..3741959d78dd 100644
--- a/maintenance/storage/checkStorage.php
+++ b/maintenance/storage/checkStorage.php
@@ -556,10 +556,27 @@ class CheckStorage {
 
 		// Find text row again
 		$dbr = wfGetDB( DB_REPLICA );
-		$oldId = $dbr->selectField( 'revision', 'rev_text_id', [ 'rev_id' => $id ], __METHOD__ );
+		global $wgMultiContentRevisionSchemaMigrationStage;
+		if ( $wgMultiContentRevisionSchemaMigrationStage & SCHEMA_COMPAT_READ_OLD ) {
+			$oldId = $dbr->selectField( 'revision', 'rev_text_id', [ 'rev_id' => $id ], __METHOD__ );
+		} else {
+			$res = $dbr->selectRow(
+				[ 'slots', 'content' ],
+				[ 'content_address' ],
+				[ 'slot_revision_id' => $id ],
+				__METHOD__,
+				[],
+				[ 'content' => [ 'INNER JOIN', [ 'content_id = slot_content_id' ] ] ]
+			);
+			// @phan-suppress-next-line PhanAccessMethodInternal
+			$blobStore = MediaWikiServices::getInstance()
+				->getBlobStoreFactory()
+				->newSqlBlobStore();
+			$oldId = $blobStore->getTextIdFromAddress( $res->content_address );
+		}
+
 		if ( !$oldId ) {
 			echo "Missing revision row for rev_id $id\n";
-
 			return;
 		}
 
diff --git a/maintenance/storage/compressOld.php b/maintenance/storage/compressOld.php
index b6aa62623a64..c4779b948a09 100644
--- a/maintenance/storage/compressOld.php
+++ b/maintenance/storage/compressOld.php
@@ -239,6 +239,10 @@ class CompressOld extends Maintenance {
 			/** @var ExternalStoreDB $storeObj */
 			$storeObj = $esFactory->getStore( 'DB' );
 		}
+		// @phan-suppress-next-line PhanAccessMethodInternal
+		$blobStore = MediaWikiServices::getInstance()
+			->getBlobStoreFactory()
+			->newSqlBlobStore();
 
 		# Get all articles by page_id
 		if ( !$maxPageId ) {
@@ -370,8 +374,12 @@ class CompressOld extends Maintenance {
 				for ( $j = 0; $j < $thisChunkSize && $chunk->isHappy(); $j++ ) {
 					$oldid = $revs[$i + $j]->old_id;
 
-					# Get text
-					$text = Revision::getRevisionText( $revs[$i + $j] );
+					# Get text. We do not need the full `extractBlob` since the query is built
+					# to fetch non-externalstore blobs.
+					$text = $blobStore->decompressData(
+						$revs[$i + $j]->old_text,
+						explode( ',', $revs[$i + $j]->old_flags )
+					);
 
 					if ( $text === false ) {
 						$this->error( "\nError, unable to get text in old_id $oldid" );
diff --git a/maintenance/storage/fixT22757.php b/maintenance/storage/fixT22757.php
deleted file mode 100644
index 61f117789921..000000000000
--- a/maintenance/storage/fixT22757.php
+++ /dev/null
@@ -1,335 +0,0 @@
-<?php
-/**
- * Script to fix T22757.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- * http://www.gnu.org/copyleft/gpl.html
- *
- * @file
- * @ingroup Maintenance ExternalStorage
- */
-
-require_once __DIR__ . '/../Maintenance.php';
-
-/**
- * Maintenance script to fix T22757.
- *
- * @ingroup Maintenance ExternalStorage
- */
-class FixT22757 extends Maintenance {
-	public $batchSize = 10000;
-	public $mapCache = [];
-	public $mapCacheSize = 0;
-	public $maxMapCacheSize = 1000000;
-
-	function __construct() {
-		parent::__construct();
-		$this->addDescription( 'Script to fix T22757 assuming that blob_tracking is intact' );
-		$this->addOption( 'dry-run', 'Report only' );
-		$this->addOption( 'start', 'old_id to start at', false, true );
-	}
-
-	function execute() {
-		$dbr = $this->getDB( DB_REPLICA );
-		$dbw = $this->getDB( DB_MASTER );
-
-		$dryRun = $this->getOption( 'dry-run' );
-		if ( $dryRun ) {
-			print "Dry run only.\n";
-		}
-
-		$startId = $this->getOption( 'start', 0 );
-		$numGood = 0;
-		$numFixed = 0;
-		$numBad = 0;
-
-		$totalRevs = $dbr->selectField( 'text', 'MAX(old_id)', '', __METHOD__ );
-
-		// In MySQL 4.1+, the binary field old_text has a non-working LOWER() function
-		$lowerLeft = 'LOWER(CONVERT(LEFT(old_text,22) USING latin1))';
-
-		while ( true ) {
-			print "ID: $startId / $totalRevs\r";
-
-			$res = $dbr->select(
-				'text',
-				[ 'old_id', 'old_flags', 'old_text' ],
-				[
-					'old_id > ' . intval( $startId ),
-					'old_flags LIKE \'%object%\' AND old_flags NOT LIKE \'%external%\'',
-					"$lowerLeft = 'o:15:\"historyblobstub\"'",
-				],
-				__METHOD__,
-				[
-					'ORDER BY' => 'old_id',
-					'LIMIT' => $this->batchSize,
-				]
-			);
-
-			if ( !$res->numRows() ) {
-				break;
-			}
-
-			$secondaryIds = [];
-			$stubs = [];
-
-			foreach ( $res as $row ) {
-				$startId = $row->old_id;
-
-				// Basic sanity checks
-				$obj = unserialize( $row->old_text );
-				if ( $obj === false ) {
-					print "{$row->old_id}: unrecoverable: cannot unserialize\n";
-					++$numBad;
-					continue;
-				}
-
-				if ( !is_object( $obj ) ) {
-					print "{$row->old_id}: unrecoverable: unserialized to type " .
-						gettype( $obj ) . ", possible double-serialization\n";
-					++$numBad;
-					continue;
-				}
-
-				if ( strtolower( get_class( $obj ) ) !== 'historyblobstub' ) {
-					print "{$row->old_id}: unrecoverable: unexpected object class " .
-						get_class( $obj ) . "\n";
-					++$numBad;
-					continue;
-				}
-
-				// Process flags
-				$flags = explode( ',', $row->old_flags );
-				if ( in_array( 'utf-8', $flags ) || in_array( 'utf8', $flags ) ) {
-					$legacyEncoding = false;
-				} else {
-					$legacyEncoding = true;
-				}
-
-				// Queue the stub for future batch processing
-				$id = intval( $obj->mOldId );
-				$secondaryIds[] = $id;
-				$stubs[$row->old_id] = [
-					'legacyEncoding' => $legacyEncoding,
-					'secondaryId' => $id,
-					'hash' => $obj->mHash,
-				];
-			}
-
-			$secondaryIds = array_unique( $secondaryIds );
-
-			if ( !count( $secondaryIds ) ) {
-				continue;
-			}
-
-			// Run the batch query on blob_tracking
-			$res = $dbr->select(
-				'blob_tracking',
-				'*',
-				[
-					'bt_text_id' => $secondaryIds,
-				],
-				__METHOD__
-			);
-			$trackedBlobs = [];
-			foreach ( $res as $row ) {
-				$trackedBlobs[$row->bt_text_id] = $row;
-			}
-
-			// Process the stubs
-			foreach ( $stubs as $primaryId => $stub ) {
-				$secondaryId = $stub['secondaryId'];
-				if ( !isset( $trackedBlobs[$secondaryId] ) ) {
-					// No tracked blob. Work out what went wrong
-					$secondaryRow = $dbr->selectRow(
-						'text',
-						[ 'old_flags', 'old_text' ],
-						[ 'old_id' => $secondaryId ],
-						__METHOD__
-					);
-					if ( !$secondaryRow ) {
-						print "$primaryId: unrecoverable: secondary row is missing\n";
-						++$numBad;
-					} elseif ( $this->isUnbrokenStub( $stub, $secondaryRow ) ) {
-						// Not broken yet, and not in the tracked clusters so it won't get
-						// broken by the current RCT run.
-						++$numGood;
-					} elseif ( strpos( $secondaryRow->old_flags, 'external' ) !== false ) {
-						print "$primaryId: unrecoverable: secondary gone to {$secondaryRow->old_text}\n";
-						++$numBad;
-					} else {
-						print "$primaryId: unrecoverable: miscellaneous corruption of secondary row\n";
-						++$numBad;
-					}
-					unset( $stubs[$primaryId] );
-					continue;
-				}
-				$trackRow = $trackedBlobs[$secondaryId];
-
-				// Check that the specified text really is available in the tracked source row
-				$url = "DB://{$trackRow->bt_cluster}/{$trackRow->bt_blob_id}/{$stub['hash']}";
-				$text = ExternalStore::fetchFromURL( $url );
-				if ( $text === false ) {
-					print "$primaryId: unrecoverable: source text missing\n";
-					++$numBad;
-					unset( $stubs[$primaryId] );
-					continue;
-				}
-				if ( md5( $text ) !== $stub['hash'] ) {
-					print "$primaryId: unrecoverable: content hashes do not match\n";
-					++$numBad;
-					unset( $stubs[$primaryId] );
-					continue;
-				}
-
-				// Find the page_id and rev_id
-				// The page is probably the same as the page of the secondary row
-				$pageId = intval( $trackRow->bt_page );
-				if ( !$pageId ) {
-					$revId = $pageId = 0;
-				} else {
-					$revId = $this->findTextIdInPage( $pageId, $primaryId );
-					if ( !$revId ) {
-						// Actually an orphan
-						$pageId = $revId = 0;
-					}
-				}
-
-				$newFlags = $stub['legacyEncoding'] ? 'external' : 'external,utf-8';
-
-				if ( !$dryRun ) {
-					// Reset the text row to point to the original copy
-					$this->beginTransaction( $dbw, __METHOD__ );
-					$dbw->update(
-						'text',
-						// SET
-						[
-							'old_flags' => $newFlags,
-							'old_text' => $url
-						],
-						// WHERE
-						[ 'old_id' => $primaryId ],
-						__METHOD__
-					);
-
-					// Add a blob_tracking row so that the new reference can be recompressed
-					// without needing to run trackBlobs.php again
-					$dbw->insert( 'blob_tracking',
-						[
-							'bt_page' => $pageId,
-							'bt_rev_id' => $revId,
-							'bt_text_id' => $primaryId,
-							'bt_cluster' => $trackRow->bt_cluster,
-							'bt_blob_id' => $trackRow->bt_blob_id,
-							'bt_cgz_hash' => $stub['hash'],
-							'bt_new_url' => null,
-							'bt_moved' => 0,
-						],
-						__METHOD__
-					);
-					$this->commitTransaction( $dbw, __METHOD__ );
-				}
-
-				print "$primaryId: resolved to $url\n";
-				++$numFixed;
-			}
-		}
-
-		print "\n";
-		print "Fixed: $numFixed\n";
-		print "Unrecoverable: $numBad\n";
-		print "Good stubs: $numGood\n";
-	}
-
-	function findTextIdInPage( $pageId, $textId ) {
-		$ids = $this->getRevTextMap( $pageId );
-		return $ids[$textId] ?? null;
-	}
-
-	function getRevTextMap( $pageId ) {
-		if ( !isset( $this->mapCache[$pageId] ) ) {
-			// Limit cache size
-			while ( $this->mapCacheSize > $this->maxMapCacheSize ) {
-				$key = key( $this->mapCache );
-				$this->mapCacheSize -= count( $this->mapCache[$key] );
-				unset( $this->mapCache[$key] );
-			}
-
-			$dbr = $this->getDB( DB_REPLICA );
-			$map = [];
-			$res = $dbr->select( 'revision',
-				[ 'rev_id', 'rev_text_id' ],
-				[ 'rev_page' => $pageId ],
-				__METHOD__
-			);
-			foreach ( $res as $row ) {
-				$map[$row->rev_text_id] = $row->rev_id;
-			}
-			$this->mapCache[$pageId] = $map;
-			$this->mapCacheSize += count( $map );
-		}
-
-		return $this->mapCache[$pageId];
-	}
-
-	/**
-	 * This is based on part of HistoryBlobStub::getText().
-	 * Determine if the text can be retrieved from the row in the normal way.
-	 * @param array $stub
-	 * @param stdClass $secondaryRow
-	 * @return bool
-	 */
-	function isUnbrokenStub( $stub, $secondaryRow ) {
-		$flags = explode( ',', $secondaryRow->old_flags );
-		$text = $secondaryRow->old_text;
-		if ( in_array( 'external', $flags ) ) {
-			$url = $text;
-			Wikimedia\suppressWarnings();
-			list( /* $proto */, $path ) = explode( '://', $url, 2 );
-			Wikimedia\restoreWarnings();
-
-			if ( $path == "" ) {
-				return false;
-			}
-			$text = ExternalStore::fetchFromURL( $url );
-		}
-		if ( !in_array( 'object', $flags ) ) {
-			return false;
-		}
-
-		if ( in_array( 'gzip', $flags ) ) {
-			$obj = unserialize( gzinflate( $text ) );
-		} else {
-			$obj = unserialize( $text );
-		}
-
-		if ( !is_object( $obj ) ) {
-			// Correct for old double-serialization bug.
-			$obj = unserialize( $obj );
-		}
-
-		if ( !is_object( $obj ) ) {
-			return false;
-		}
-
-		$obj->uncompress();
-		$text = $obj->getItem( $stub['hash'] );
-
-		return $text !== false;
-	}
-}
-
-$maintClass = FixT22757::class;
-require_once RUN_MAINTENANCE_IF_MAIN;
diff --git a/maintenance/storage/recompressTracked.php b/maintenance/storage/recompressTracked.php
index 9f20e670acae..5cd6ef306cf9 100644
--- a/maintenance/storage/recompressTracked.php
+++ b/maintenance/storage/recompressTracked.php
@@ -22,6 +22,7 @@
  * @ingroup Maintenance ExternalStorage
  */
 
+use MediaWiki\Storage\SqlBlobStore;
 use Wikimedia\Rdbms\IMaintainableDatabase;
 use MediaWiki\Logger\LegacyLogger;
 use MediaWiki\MediaWikiServices;
@@ -71,6 +72,8 @@ class RecompressTracked {
 	public $debugLog, $infoLog, $criticalLog;
 	/** @var ExternalStoreDB */
 	public $store;
+	/** @var SqlBlobStore */
+	private $blobStore;
 
 	private static $optionsWithArgs = [
 		'procs',
@@ -120,6 +123,10 @@ class RecompressTracked {
 		$this->pageBlobClass = function_exists( 'xdiff_string_bdiff' ) ?
 			DiffHistoryBlob::class : ConcatenatedGzipHistoryBlob::class;
 		$this->orphanBlobClass = ConcatenatedGzipHistoryBlob::class;
+		// @phan-suppress-next-line PhanAccessMethodInternal
+		$this->blobStore = MediaWikiServices::getInstance()
+			->getBlobStoreFactory()
+			->newSqlBlobStore();
 	}
 
 	function debug( $msg ) {
@@ -531,7 +538,7 @@ class RecompressTracked {
 				}
 				$lastTextId = $row->bt_text_id;
 				// Load the text
-				$text = Revision::getRevisionText( $row );
+				$text = $this->blobStore->expandBlob( $row->old_text, $row->old_flags );
 				if ( $text === false ) {
 					$this->critical( "Error loading {$row->bt_rev_id}/{$row->bt_text_id}" );
 					continue;
@@ -685,7 +692,7 @@ class RecompressTracked {
 		);
 
 		foreach ( $res as $row ) {
-			$text = Revision::getRevisionText( $row );
+			$text = $this->blobStore->expandBlob( $row->old_text, $row->old_flags );
 			if ( $text === false ) {
 				$this->critical( "Error: cannot load revision text for old_id={$row->old_id}" );
 				continue;