X-Git-Url: http://git.cyclocoop.org/?a=blobdiff_plain;f=includes%2Flibs%2Frdbms%2Fdatabase%2FDatabase.php;h=92b94716d87ac2d9f0919e70d25f161153c618be;hb=2b4c62b597188116e2ae41f1547f81ed1ec5104f;hp=5451476042aed2b331cb1f0117f17e7655dabddd;hpb=c1cf26c04d4f4e2d179db3c0c361042ad14353c2;p=lhc%2Fweb%2Fwiklou.git

diff --git a/includes/libs/rdbms/database/Database.php b/includes/libs/rdbms/database/Database.php
index 5451476042..92b94716d8 100644
--- a/includes/libs/rdbms/database/Database.php
+++ b/includes/libs/rdbms/database/Database.php
@@ -38,6 +38,7 @@ use InvalidArgumentException;
 use UnexpectedValueException;
 use Exception;
 use RuntimeException;
+use Throwable;
 
 /**
  * Relational database abstraction object
@@ -74,7 +75,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	protected $delimiter = ';';
 	/** @var string|bool|null Stashed value of html_errors INI setting */
 	protected $htmlErrors;
-	/** @var int */
+	/** @var int Row batch size to use for emulated INSERT SELECT queries */
 	protected $nonNativeInsertSelectBatchSize = 10000;
 
 	/** @var BagOStuff APC cache */
@@ -93,22 +94,18 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	protected $trxProfiler;
 	/** @var DatabaseDomain */
 	protected $currentDomain;
+	/** @var object|resource|null Database connection */
+	protected $conn;
+
 	/** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 	private $lazyMasterHandle;
 
-	/** @var object|resource|null Database connection */
-	protected $conn = null;
-	/** @var bool Whether a connection handle is open (connection itself might be dead) */
-	protected $opened = false;
-
 	/** @var array Map of (name => 1) for locks obtained via lock() */
 	protected $sessionNamedLocks = [];
 	/** @var array Map of (table name => 1) for TEMPORARY tables */
 	protected $sessionTempTables = [];
 
-	/** @var int Whether there is an active transaction (1 or 0) */
-	protected $trxLevel = 0;
-	/** @var string Hexidecimal string if a transaction is active or empty string otherwise */
+	/** @var string ID of the active transaction or the empty string otherwise */
 	protected $trxShortId = '';
 	/** @var int Transaction status */
 	protected $trxStatus = self::STATUS_TRX_NONE;
@@ -150,6 +147,8 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	private $trxPreCommitCallbacks = [];
 	/** @var array[] List of (callable, method name, atomic section id) */
 	private $trxEndCallbacks = [];
+	/** @var array[] List of (callable, method name, atomic section id) */
+	private $trxSectionCancelCallbacks = [];
 	/** @var callable[] Map of (name => callable) */
 	private $trxRecurringCallbacks = [];
 	/** @var bool Whether to suppress triggering of transaction end callbacks */
@@ -308,7 +307,6 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 * @param string $dbName Database name
 	 * @param string|null $schema Database schema name
 	 * @param string $tablePrefix Table prefix
-	 * @return bool
 	 * @throws DBConnectionError
 	 */
 	abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
@@ -512,12 +510,12 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		return $res;
 	}
 
-	public function trxLevel() {
-		return $this->trxLevel;
+	final public function trxLevel() {
+		return ( $this->trxShortId != '' ) ? 1 : 0;
 	}
 
 	public function trxTimestamp() {
-		return $this->trxLevel ? $this->trxTimestamp : null;
+		return $this->trxLevel() ? $this->trxTimestamp : null;
 	}
 
 	/**
@@ -620,20 +618,21 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	public function writesPending() {
-		return $this->trxLevel && $this->trxDoneWrites;
+		return $this->trxLevel() && $this->trxDoneWrites;
 	}
 
 	public function writesOrCallbacksPending() {
-		return $this->trxLevel && (
+		return $this->trxLevel() && (
 			$this->trxDoneWrites ||
 			$this->trxIdleCallbacks ||
 			$this->trxPreCommitCallbacks ||
-			$this->trxEndCallbacks
+			$this->trxEndCallbacks ||
+			$this->trxSectionCancelCallbacks
 		);
 	}
 
 	public function preCommitCallbacksPending() {
-		return $this->trxLevel && $this->trxPreCommitCallbacks;
+		return $this->trxLevel() && $this->trxPreCommitCallbacks;
 	}
 
 	/**
@@ -651,7 +650,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
-		if ( !$this->trxLevel ) {
+		if ( !$this->trxLevel() ) {
 			return false;
 		} elseif ( !$this->trxDoneWrites ) {
 			return 0.0;
@@ -681,7 +680,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	public function pendingWriteCallers() {
-		return $this->trxLevel ? $this->trxWriteCallers : [];
+		return $this->trxLevel() ? $this->trxWriteCallers : [];
 	}
 
 	public function pendingWriteRowsAffected() {
@@ -701,7 +700,8 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		foreach ( [
 			$this->trxIdleCallbacks,
 			$this->trxPreCommitCallbacks,
-			$this->trxEndCallbacks
+			$this->trxEndCallbacks,
+			$this->trxSectionCancelCallbacks
 		] as $callbacks ) {
 			foreach ( $callbacks as $callback ) {
 				$fnames[] = $callback[1];
@@ -721,7 +721,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	public function isOpen() {
-		return $this->opened;
+		return (bool)$this->conn;
 	}
 
 	public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
@@ -865,11 +865,11 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	final public function close() {
 		$exception = null; // error to throw after disconnecting
 
-		$wasOpen = $this->opened;
+		$wasOpen = (bool)$this->conn;
 		// This should mostly do nothing if the connection is already closed
 		if ( $this->conn ) {
 			// Roll back any dangling transaction first
-			if ( $this->trxLevel ) {
+			if ( $this->trxLevel() ) {
 				if ( $this->trxAtomicLevels ) {
 					// Cannot let incomplete atomic sections be committed
 					$levels = $this->flatAtomicSectionList();
@@ -914,7 +914,6 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		}
 
 		$this->conn = false;
-		$this->opened = false;
 
 		// Throw any unexpected errors after having disconnected
 		if ( $exception instanceof Exception ) {
@@ -978,16 +977,6 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 */
 	abstract protected function closeConnection();
 
-	/**
-	 * @deprecated since 1.32
-	 * @param string $error Fallback message, if none is given by DB
-	 * @throws DBConnectionError
-	 */
-	public function reportConnectionError( $error = 'Unknown error' ) {
-		call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
-		throw new DBConnectionError( $this, $this->lastError() ?: $error );
-	}
-
 	/**
 	 * Run a query and return a DBMS-dependent wrapper or boolean
 	 *
@@ -1005,8 +994,8 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 * For SELECT queries, this returns either:
 	 *   - a) A driver-specific value/resource, only on success. This can be iterated
 	 *        over by calling fetchObject()/fetchRow() until there are no more rows.
-	 *        Alternatively, the result can be passed to resultObject() to obtain a
-	 *        ResultWrapper instance which can then be iterated over via "foreach".
+	 *        Alternatively, the result can be passed to resultObject() to obtain an
+	 *        IResultWrapper instance which can then be iterated over via "foreach".
 	 *   - b) False, on any query failure
 	 *
 	 * For non-SELECT queries, this returns either:
@@ -1079,7 +1068,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	protected function isTransactableQuery( $sql ) {
 		return !in_array(
 			$this->getQueryVerb( $sql ),
-			[ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE' ],
+			[ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE', 'SHOW' ],
 			true
 		);
 	}
@@ -1087,9 +1076,12 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	/**
 	 * @param string $sql A SQL query
 	 * @param bool $pseudoPermanent Treat any table from CREATE TEMPORARY as pseudo-permanent
-	 * @return int|null A self::TEMP_* constant for temp table operations or null otherwise
+	 * @return array A n-tuple of:
+	 *   - int|null: A self::TEMP_* constant for temp table operations or null otherwise
+	 *   - string|null: The name of the new temporary table $sql creates, or null
+	 *   - string|null: The name of the temporary table that $sql drops, or null
 	 */
-	protected function registerTempTableWrite( $sql, $pseudoPermanent ) {
+	protected function getTempWrites( $sql, $pseudoPermanent ) {
 		static $qt = '[`"\']?(\w+)[`"\']?'; // quoted table
 
 		if ( preg_match(
@@ -1098,33 +1090,46 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 			$matches
 		) ) {
 			$type = $pseudoPermanent ? self::$TEMP_PSEUDO_PERMANENT : self::$TEMP_NORMAL;
-			$this->sessionTempTables[$matches[1]] = $type;
 
-			return $type;
+			return [ $type, $matches[1], null ];
 		} elseif ( preg_match(
 			'/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
 			$sql,
 			$matches
 		) ) {
-			$type = $this->sessionTempTables[$matches[1]] ?? null;
-			unset( $this->sessionTempTables[$matches[1]] );
-
-			return $type;
+			return [ $this->sessionTempTables[$matches[1]] ?? null, null, $matches[1] ];
 		} elseif ( preg_match(
 			'/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
 			$sql,
 			$matches
 		) ) {
-			return $this->sessionTempTables[$matches[1]] ?? null;
+			return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
 		} elseif ( preg_match(
 			'/^(?:(?:INSERT|REPLACE)\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+' . $qt . '/i',
 			$sql,
 			$matches
 		) ) {
-			return $this->sessionTempTables[$matches[1]] ?? null;
+			return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
 		}
 
-		return null;
+		return [ null, null, null ];
+	}
+
+	/**
+	 * @param IResultWrapper|bool $ret
+	 * @param int|null $tmpType TEMP_NORMAL or TEMP_PSEUDO_PERMANENT
+	 * @param string|null $tmpNew Name of created temp table
+	 * @param string|null $tmpDel Name of dropped temp table
+	 */
+	protected function registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel ) {
+		if ( $ret !== false ) {
+			if ( $tmpNew !== null ) {
+				$this->sessionTempTables[$tmpNew] = $tmpType;
+			}
+			if ( $tmpDel !== null ) {
+				unset( $this->sessionTempTables[$tmpDel] );
+			}
+		}
 	}
 
 	public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
@@ -1167,40 +1172,49 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	final protected function executeQuery( $sql, $fname, $flags ) {
 		$this->assertHasConnectionHandle();
 
-		$priorTransaction = $this->trxLevel;
+		$priorTransaction = $this->trxLevel();
 
 		if ( $this->isWriteQuery( $sql ) ) {
-			# In theory, non-persistent writes are allowed in read-only mode, but due to things
-			# like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
+			// In theory, non-persistent writes are allowed in read-only mode, but due to things
+			// like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 			$this->assertIsWritableMaster();
-			# Do not treat temporary table writes as "meaningful writes" since they are only
-			# visible to one session and are not permanent. Profile them as reads. Integration
-			# tests can override this behavior via $flags.
+			// Do not treat temporary table writes as "meaningful writes" since they are only
+			// visible to one session and are not permanent. Profile them as reads. Integration
+			// tests can override this behavior via $flags.
 			$pseudoPermanent = $this->hasFlags( $flags, self::QUERY_PSEUDO_PERMANENT );
-			$tableType = $this->registerTempTableWrite( $sql, $pseudoPermanent );
-			$isPermWrite = ( $tableType !== self::$TEMP_NORMAL );
-			# DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
+			list( $tmpType, $tmpNew, $tmpDel ) = $this->getTempWrites( $sql, $pseudoPermanent );
+			$isPermWrite = ( $tmpType !== self::$TEMP_NORMAL );
+			// DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
 			if ( $isPermWrite && $this->hasFlags( $flags, self::QUERY_REPLICA_ROLE ) ) {
 				throw new DBReadOnlyRoleError( $this, "Cannot write; target role is DB_REPLICA" );
 			}
 		} else {
+			// No permanent writes in this query
 			$isPermWrite = false;
+			// No temporary tables written to either
+			list( $tmpType, $tmpNew, $tmpDel ) = [ null, null, null ];
 		}
 
 		// Add trace comment to the begin of the sql string, right after the operator.
 		// Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 		$commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 
-		// Send the query to the server and fetch any corresponding errors
+		// Send the query to the server and fetch any corresponding errors.
+		// This also doubles as a "ping" to see if the connection was dropped.
 		list( $ret, $err, $errno, $recoverableSR, $recoverableCL, $reconnected ) =
 			$this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
+
 		// Check if the query failed due to a recoverable connection loss
-		if ( $ret === false && $recoverableCL && $reconnected ) {
+		$allowRetry = !$this->hasFlags( $flags, self::QUERY_NO_RETRY );
+		if ( $ret === false && $recoverableCL && $reconnected && $allowRetry ) {
 			// Silently resend the query to the server since it is safe and possible
 			list( $ret, $err, $errno, $recoverableSR, $recoverableCL ) =
 				$this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
 		}
 
+		// Register creation and dropping of temporary tables
+		$this->registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel );
+
 		$corruptedTrx = false;
 
 		if ( $ret === false ) {
@@ -1255,7 +1269,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		// Keep track of whether the transaction has write queries pending
 		if ( $isPermWrite ) {
 			$this->lastWriteTime = microtime( true );
-			if ( $this->trxLevel && !$this->trxDoneWrites ) {
+			if ( $this->trxLevel() && !$this->trxDoneWrites ) {
 				$this->trxDoneWrites = true;
 				$this->trxProfiler->transactionWritingIn(
 					$this->server, $this->getDomainID(), $this->trxShortId );
@@ -1285,7 +1299,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 
 		if ( $ret !== false ) {
 			$this->lastPing = $startTime;
-			if ( $isPermWrite && $this->trxLevel ) {
+			if ( $isPermWrite && $this->trxLevel() ) {
 				$this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
 				$this->trxWriteCallers[] = $fname;
 			}
@@ -1334,7 +1348,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 */
 	private function beginIfImplied( $sql, $fname ) {
 		if (
-			!$this->trxLevel &&
+			!$this->trxLevel() &&
 			$this->getFlag( self::DBO_TRX ) &&
 			$this->isTransactableQuery( $sql )
 		) {
@@ -1464,7 +1478,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		// https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
 		$this->sessionNamedLocks = [];
 		// Session loss implies transaction loss
-		$this->trxLevel = 0;
+		$oldTrxShortId = $this->consumeTrxShortId();
 		$this->trxAtomicCounter = 0;
 		$this->trxIdleCallbacks = []; // T67263; transaction already lost
 		$this->trxPreCommitCallbacks = []; // T67263; transaction already lost
@@ -1473,7 +1487,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 			$this->trxProfiler->transactionWritingOut(
 				$this->server,
 				$this->getDomainID(),
-				$this->trxShortId,
+				$oldTrxShortId,
 				$this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
 				$this->trxWriteAffectedRows
 			);
@@ -1499,6 +1513,18 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		}
 	}
 
+	/**
+	 * Reset the transaction ID and return the old one
+	 *
+	 * @return string The old transaction ID or the empty string if there wasn't one
+	 */
+	private function consumeTrxShortId() {
+		$old = $this->trxShortId;
+		$this->trxShortId = '';
+
+		return $old;
+	}
+
 	/**
 	 * Checks whether the cause of the error is detected to be a timeout.
 	 *
@@ -1996,7 +2022,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	public function lockForUpdate(
 		$table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 	) {
-		if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
+		if ( !$this->trxLevel() && !$this->getFlag( self::DBO_TRX ) ) {
 			throw new DBUnexpectedError(
 				$this,
 				__METHOD__ . ': no transaction is active nor is DBO_TRX set'
@@ -3343,21 +3369,21 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
-		if ( !$this->trxLevel ) {
+		if ( !$this->trxLevel() ) {
 			throw new DBUnexpectedError( $this, "No transaction is active." );
 		}
 		$this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
 	}
 
 	final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
-		if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
+		if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
 			// Start an implicit transaction similar to how query() does
 			$this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 			$this->trxAutomatic = true;
 		}
 
 		$this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
-		if ( !$this->trxLevel ) {
+		if ( !$this->trxLevel() ) {
 			$this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
 		}
 	}
@@ -3367,13 +3393,13 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
-		if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
+		if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
 			// Start an implicit transaction similar to how query() does
 			$this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 			$this->trxAutomatic = true;
 		}
 
-		if ( $this->trxLevel ) {
+		if ( $this->trxLevel() ) {
 			$this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
 		} else {
 			// No transaction is active nor will start implicitly, so make one for this callback
@@ -3388,11 +3414,18 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		}
 	}
 
+	final public function onAtomicSectionCancel( callable $callback, $fname = __METHOD__ ) {
+		if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
+			throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
+		}
+		$this->trxSectionCancelCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
+	}
+
 	/**
 	 * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
 	 */
 	private function currentAtomicSectionId() {
-		if ( $this->trxLevel && $this->trxAtomicLevels ) {
+		if ( $this->trxLevel() && $this->trxAtomicLevels ) {
 			$levelInfo = end( $this->trxAtomicLevels );
 
 			return $levelInfo[1];
@@ -3402,6 +3435,8 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	/**
+	 * Hoist callback ownership for callbacks in a section to a parent section.
+	 * All callbacks should have an owner that is present in trxAtomicLevels.
 	 * @param AtomicSectionIdentifier $old
 	 * @param AtomicSectionIdentifier $new
 	 */
@@ -3423,13 +3458,35 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 				$this->trxEndCallbacks[$key][2] = $new;
 			}
 		}
+		foreach ( $this->trxSectionCancelCallbacks as $key => $info ) {
+			if ( $info[2] === $old ) {
+				$this->trxSectionCancelCallbacks[$key][2] = $new;
+			}
+		}
 	}
 
 	/**
+	 * Update callbacks that were owned by cancelled atomic sections.
+	 *
+	 * Callbacks for "on commit" should never be run if they're owned by a
+	 * section that won't be committed.
+	 *
+	 * Callbacks for "on resolution" need to reflect that the section was
+	 * rolled back, even if the transaction as a whole commits successfully.
+	 *
+	 * Callbacks for "on section cancel" should already have been consumed,
+	 * but errors during the cancellation itself can prevent that while still
+	 * destroying the section. Hoist any such callbacks to the new top section,
+	 * which we assume will itself have to be cancelled or rolled back to
+	 * resolve the error.
+	 *
 	 * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
+	 * @param AtomicSectionIdentifier|null $newSectionId New top section ID.
 	 * @throws UnexpectedValueException
 	 */
-	private function modifyCallbacksForCancel( array $sectionIds ) {
+	private function modifyCallbacksForCancel(
+		array $sectionIds, AtomicSectionIdentifier $newSectionId = null
+	) {
 		// Cancel the "on commit" callbacks owned by this savepoint
 		$this->trxIdleCallbacks = array_filter(
 			$this->trxIdleCallbacks,
@@ -3448,8 +3505,17 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 			if ( in_array( $entry[2], $sectionIds, true ) ) {
 				$callback = $entry[0];
 				$this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
+					// @phan-suppress-next-line PhanInfiniteRecursion No recursion at all here, phan is confused
 					return $callback( self::TRIGGER_ROLLBACK, $this );
 				};
+				// This "on resolution" callback no longer belongs to a section.
+				$this->trxEndCallbacks[$key][2] = null;
+			}
+		}
+		// Hoist callback ownership for section cancel callbacks to the new top section
+		foreach ( $this->trxSectionCancelCallbacks as $key => $entry ) {
+			if ( in_array( $entry[2], $sectionIds, true ) ) {
+				$this->trxSectionCancelCallbacks[$key][2] = $newSectionId;
 			}
 		}
 	}
@@ -3485,7 +3551,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 * @throws Exception
 	 */
 	public function runOnTransactionIdleCallbacks( $trigger ) {
-		if ( $this->trxLevel ) { // sanity
+		if ( $this->trxLevel() ) { // sanity
 			throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
 		}
 
@@ -3504,6 +3570,14 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 			);
 			$this->trxIdleCallbacks = []; // consumed (and recursion guard)
 			$this->trxEndCallbacks = []; // consumed (recursion guard)
+
+			// Only run trxSectionCancelCallbacks on rollback, not commit.
+			// But always consume them.
+			if ( $trigger === self::TRIGGER_ROLLBACK ) {
+				$callbacks = array_merge( $callbacks, $this->trxSectionCancelCallbacks );
+			}
+			$this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
+
 			foreach ( $callbacks as $callback ) {
 				++$count;
 				list( $phpCallback ) = $callback;
@@ -3571,6 +3645,46 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		return $count;
 	}
 
+	/**
+	 * Actually run any "atomic section cancel" callbacks.
+	 *
+	 * @param int $trigger IDatabase::TRIGGER_* constant
+	 * @param AtomicSectionIdentifier[]|null $sectionIds Section IDs to cancel,
+	 *  null on transaction rollback
+	 */
+	private function runOnAtomicSectionCancelCallbacks(
+		$trigger, array $sectionIds = null
+	) {
+		/** @var Exception|Throwable $e */
+		$e = null; // first exception
+
+		$notCancelled = [];
+		do {
+			$callbacks = $this->trxSectionCancelCallbacks;
+			$this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
+			foreach ( $callbacks as $entry ) {
+				if ( $sectionIds === null || in_array( $entry[2], $sectionIds, true ) ) {
+					try {
+						$entry[0]( $trigger, $this );
+					} catch ( Exception $ex ) {
+						( $this->errorLogger )( $ex );
+						$e = $e ?: $ex;
+					} catch ( Throwable $ex ) {
+						// @todo: Log?
+						$e = $e ?: $ex;
+					}
+				} else {
+					$notCancelled[] = $entry;
+				}
+			}
+		} while ( count( $this->trxSectionCancelCallbacks ) );
+		$this->trxSectionCancelCallbacks = $notCancelled;
+
+		if ( $e !== null ) {
+			throw $e; // re-throw any first Exception/Throwable
+		}
+	}
+
 	/**
 	 * Actually run any "transaction listener" callbacks.
 	 *
@@ -3668,7 +3782,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	) {
 		$savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
 
-		if ( !$this->trxLevel ) {
+		if ( !$this->trxLevel() ) {
 			$this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
 			// If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
 			// in all changes being in one transaction to keep requests transactional.
@@ -3694,7 +3808,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	final public function endAtomic( $fname = __METHOD__ ) {
-		if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
+		if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
 			throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
 		}
 
@@ -3730,71 +3844,83 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	final public function cancelAtomic(
 		$fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
 	) {
-		if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
+		if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
 			throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
 		}
 
-		$excisedFnames = [];
-		if ( $sectionId !== null ) {
-			// Find the (last) section with the given $sectionId
-			$pos = -1;
-			foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
-				if ( $asId === $sectionId ) {
-					$pos = $i;
+		$excisedIds = [];
+		$newTopSection = $this->currentAtomicSectionId();
+		try {
+			$excisedFnames = [];
+			if ( $sectionId !== null ) {
+				// Find the (last) section with the given $sectionId
+				$pos = -1;
+				foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
+					if ( $asId === $sectionId ) {
+						$pos = $i;
+					}
 				}
+				if ( $pos < 0 ) {
+					throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
+				}
+				// Remove all descendant sections and re-index the array
+				$len = count( $this->trxAtomicLevels );
+				for ( $i = $pos + 1; $i < $len; ++$i ) {
+					$excisedFnames[] = $this->trxAtomicLevels[$i][0];
+					$excisedIds[] = $this->trxAtomicLevels[$i][1];
+				}
+				$this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
+				$newTopSection = $this->currentAtomicSectionId();
 			}
-			if ( $pos < 0 ) {
-				throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
-			}
-			// Remove all descendant sections and re-index the array
-			$excisedIds = [];
-			$len = count( $this->trxAtomicLevels );
-			for ( $i = $pos + 1; $i < $len; ++$i ) {
-				$excisedFnames[] = $this->trxAtomicLevels[$i][0];
-				$excisedIds[] = $this->trxAtomicLevels[$i][1];
-			}
-			$this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
-			$this->modifyCallbacksForCancel( $excisedIds );
-		}
 
-		// Check if the current section matches $fname
-		$pos = count( $this->trxAtomicLevels ) - 1;
-		list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
+			// Check if the current section matches $fname
+			$pos = count( $this->trxAtomicLevels ) - 1;
+			list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
 
-		if ( $excisedFnames ) {
-			$this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
-				"and descendants " . implode( ', ', $excisedFnames ) );
-		} else {
-			$this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
-		}
+			if ( $excisedFnames ) {
+				$this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
+					"and descendants " . implode( ', ', $excisedFnames ) );
+			} else {
+				$this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
+			}
 
-		if ( $savedFname !== $fname ) {
-			throw new DBUnexpectedError(
-				$this,
-				"Invalid atomic section ended (got $fname but expected $savedFname)."
-			);
-		}
+			if ( $savedFname !== $fname ) {
+				throw new DBUnexpectedError(
+					$this,
+					"Invalid atomic section ended (got $fname but expected $savedFname)."
+				);
+			}
 
-		// Remove the last section (no need to re-index the array)
-		array_pop( $this->trxAtomicLevels );
-		$this->modifyCallbacksForCancel( [ $savedSectionId ] );
+			// Remove the last section (no need to re-index the array)
+			array_pop( $this->trxAtomicLevels );
+			$excisedIds[] = $savedSectionId;
+			$newTopSection = $this->currentAtomicSectionId();
 
-		if ( $savepointId !== null ) {
-			// Rollback the transaction to the state just before this atomic section
-			if ( $savepointId === self::$NOT_APPLICABLE ) {
-				$this->rollback( $fname, self::FLUSHING_INTERNAL );
-			} else {
-				$this->doRollbackToSavepoint( $savepointId, $fname );
-				$this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
-				$this->trxStatusIgnoredCause = null;
+			if ( $savepointId !== null ) {
+				// Rollback the transaction to the state just before this atomic section
+				if ( $savepointId === self::$NOT_APPLICABLE ) {
+					$this->rollback( $fname, self::FLUSHING_INTERNAL );
+					// Note: rollback() will run trxSectionCancelCallbacks
+				} else {
+					$this->doRollbackToSavepoint( $savepointId, $fname );
+					$this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
+					$this->trxStatusIgnoredCause = null;
+
+					// Run trxSectionCancelCallbacks now.
+					$this->runOnAtomicSectionCancelCallbacks( self::TRIGGER_CANCEL, $excisedIds );
+				}
+			} elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
+				// Put the transaction into an error state if it's not already in one
+				$this->trxStatus = self::STATUS_TRX_ERROR;
+				$this->trxStatusCause = new DBUnexpectedError(
+					$this,
+					"Uncancelable atomic section canceled (got $fname)."
+				);
 			}
-		} elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
-			// Put the transaction into an error state if it's not already in one
-			$this->trxStatus = self::STATUS_TRX_ERROR;
-			$this->trxStatusCause = new DBUnexpectedError(
-				$this,
-				"Uncancelable atomic section canceled (got $fname)."
-			);
+		} finally {
+			// Fix up callbacks owned by the sections that were just cancelled.
+			// All callbacks should have an owner that is present in trxAtomicLevels.
+			$this->modifyCallbacksForCancel( $excisedIds, $newTopSection );
 		}
 
 		$this->affectedRowCount = 0; // for the sake of consistency
@@ -3823,7 +3949,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		}
 
 		// Protect against mismatched atomic section, transaction nesting, and snapshot loss
-		if ( $this->trxLevel ) {
+		if ( $this->trxLevel() ) {
 			if ( $this->trxAtomicLevels ) {
 				$levels = $this->flatAtomicSectionList();
 				$msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
@@ -3843,6 +3969,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		$this->assertHasConnectionHandle();
 
 		$this->doBegin( $fname );
+		$this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
 		$this->trxStatus = self::STATUS_TRX_OK;
 		$this->trxStatusIgnoredCause = null;
 		$this->trxAtomicCounter = 0;
@@ -3851,7 +3978,6 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		$this->trxDoneWrites = false;
 		$this->trxAutomaticAtomic = false;
 		$this->trxAtomicLevels = [];
-		$this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
 		$this->trxWriteDuration = 0.0;
 		$this->trxWriteQueryCount = 0;
 		$this->trxWriteAffectedRows = 0;
@@ -3873,10 +3999,10 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 *
 	 * @see Database::begin()
 	 * @param string $fname
+	 * @throws DBError
 	 */
 	protected function doBegin( $fname ) {
 		$this->query( 'BEGIN', $fname );
-		$this->trxLevel = 1;
 	}
 
 	final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
@@ -3885,7 +4011,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 			throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
 		}
 
-		if ( $this->trxLevel && $this->trxAtomicLevels ) {
+		if ( $this->trxLevel() && $this->trxAtomicLevels ) {
 			// There are still atomic sections open; this cannot be ignored
 			$levels = $this->flatAtomicSectionList();
 			throw new DBUnexpectedError(
@@ -3895,7 +4021,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 		}
 
 		if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
-			if ( !$this->trxLevel ) {
+			if ( !$this->trxLevel() ) {
 				return; // nothing to do
 			} elseif ( !$this->trxAutomatic ) {
 				throw new DBUnexpectedError(
@@ -3903,7 +4029,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 					"$fname: Flushing an explicit transaction, getting out of sync."
 				);
 			}
-		} elseif ( !$this->trxLevel ) {
+		} elseif ( !$this->trxLevel() ) {
 			$this->queryLogger->error(
 				"$fname: No transaction to commit, something got out of sync." );
 			return; // nothing to do
@@ -3920,6 +4046,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 
 		$writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
 		$this->doCommit( $fname );
+		$oldTrxShortId = $this->consumeTrxShortId();
 		$this->trxStatus = self::STATUS_TRX_NONE;
 
 		if ( $this->trxDoneWrites ) {
@@ -3927,7 +4054,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 			$this->trxProfiler->transactionWritingOut(
 				$this->server,
 				$this->getDomainID(),
-				$this->trxShortId,
+				$oldTrxShortId,
 				$writeTime,
 				$this->trxWriteAffectedRows
 			);
@@ -3945,16 +4072,16 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 *
 	 * @see Database::commit()
 	 * @param string $fname
+	 * @throws DBError
 	 */
 	protected function doCommit( $fname ) {
-		if ( $this->trxLevel ) {
+		if ( $this->trxLevel() ) {
 			$this->query( 'COMMIT', $fname );
-			$this->trxLevel = 0;
 		}
 	}
 
 	final public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
-		$trxActive = $this->trxLevel;
+		$trxActive = $this->trxLevel();
 
 		if ( $flush !== self::FLUSHING_INTERNAL
 			&& $flush !== self::FLUSHING_ALL_PEERS
@@ -3970,6 +4097,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 			$this->assertHasConnectionHandle();
 
 			$this->doRollback( $fname );
+			$oldTrxShortId = $this->consumeTrxShortId();
 			$this->trxStatus = self::STATUS_TRX_NONE;
 			$this->trxAtomicLevels = [];
 			// Estimate the RTT via a query now that trxStatus is OK
@@ -3979,7 +4107,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 				$this->trxProfiler->transactionWritingOut(
 					$this->server,
 					$this->getDomainID(),
-					$this->trxShortId,
+					$oldTrxShortId,
 					$writeTime,
 					$this->trxWriteAffectedRows
 				);
@@ -4013,13 +4141,13 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 *
 	 * @see Database::rollback()
 	 * @param string $fname
+	 * @throws DBError
 	 */
 	protected function doRollback( $fname ) {
-		if ( $this->trxLevel ) {
+		if ( $this->trxLevel() ) {
 			# Disconnects cause rollback anyway, so ignore those errors
 			$ignoreErrors = true;
 			$this->query( 'ROLLBACK', $fname, $ignoreErrors );
-			$this->trxLevel = 0;
 		}
 	}
 
@@ -4037,7 +4165,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	public function explicitTrxActive() {
-		return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
+		return $this->trxLevel() && ( $this->trxAtomicLevels || !$this->trxAutomatic );
 	}
 
 	public function duplicateTableStructure(
@@ -4080,9 +4208,8 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	abstract protected function fetchAffectedRowCount();
 
 	/**
-	 * Take the result from a query, and wrap it in a ResultWrapper if
-	 * necessary. Boolean values are passed through as is, to indicate success
-	 * of write queries or failure.
+	 * Take a query result and wrap it in an iterable result wrapper if necessary.
+	 * Booleans are passed through as-is to indicate success/failure of write queries.
 	 *
 	 * Once upon a time, Database::query() returned a bare MySQL result
 	 * resource, and it was necessary to call this function to convert it to
@@ -4094,12 +4221,11 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 */
 	protected function resultObject( $result ) {
 		if ( !$result ) {
-			return false;
-		} elseif ( $result instanceof ResultWrapper ) {
+			return false; // failed query
+		} elseif ( $result instanceof IResultWrapper ) {
 			return $result;
 		} elseif ( $result === true ) {
-			// Successful write query
-			return $result;
+			return $result; // succesful write query
 		} else {
 			return new ResultWrapper( $this, $result );
 		}
@@ -4134,7 +4260,6 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 */
 	protected function replaceLostConnection( $fname ) {
 		$this->closeConnection();
-		$this->opened = false;
 		$this->conn = false;
 
 		$this->handleSessionLossPreconnect();
@@ -4190,7 +4315,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 * @since 1.27
 	 */
 	final protected function getRecordedTransactionLagStatus() {
-		return ( $this->trxLevel && $this->trxReplicaLag !== null )
+		return ( $this->trxLevel() && $this->trxReplicaLag !== null )
 			? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
 			: null;
 	}
@@ -4245,6 +4370,16 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	}
 
 	public function getLag() {
+		if ( $this->getLBInfo( 'master' ) ) {
+			return 0; // this is the master
+		} elseif ( $this->getLBInfo( 'is static' ) ) {
+			return 0; // static dataset
+		}
+
+		return $this->doGetLag();
+	}
+
+	protected function doGetLag() {
 		return 0;
 	}
 
@@ -4698,9 +4833,9 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 
 		if ( $this->isOpen() ) {
 			// Open a new connection resource without messing with the old one
-			$this->opened = false;
 			$this->conn = false;
 			$this->trxEndCallbacks = []; // don't copy
+			$this->trxSectionCancelCallbacks = []; // don't copy
 			$this->handleSessionLossPreconnect(); // no trx or locks anymore
 			$this->open(
 				$this->server,
@@ -4728,7 +4863,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 	 * Run a few simple sanity checks and close dangling connections
 	 */
 	public function __destruct() {
-		if ( $this->trxLevel && $this->trxDoneWrites ) {
+		if ( $this->trxLevel() && $this->trxDoneWrites ) {
 			trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
 		}
 
@@ -4745,7 +4880,6 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 			$this->closeConnection();
 			Wikimedia\restoreWarnings();
 			$this->conn = false;
-			$this->opened = false;
 		}
 	}
 }