public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
global $wgUser;
+ $priorWritesPending = $this->writesOrCallbacksPending();
$this->mLastQuery = $sql;
$isWriteQuery = $this->isWriteQuery( $sql );
// Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
$commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
- if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX ) && $this->isTransactableQuery( $sql ) ) {
+ # Start implicit transactions that wrap the request if DBO_TRX is enabled
+ if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
+ && $this->isTransactableQuery( $sql )
+ ) {
$this->begin( __METHOD__ . " ($fname)" );
$this->mTrxAutomatic = true;
}
# Try reconnecting if the connection was lost
if ( false === $ret && $this->wasErrorReissuable() ) {
- # Transaction is gone; this can mean lost writes or REPEATABLE-READ snapshots
- $hadTrx = $this->mTrxLevel;
- # T127428: for non-write transactions, a disconnect and a COMMIT are similar:
- # neither changed data and in both cases any read snapshots are reset anyway.
- $isNoopCommit = ( !$this->writesOrCallbacksPending() && $sql === 'COMMIT' );
- # Update state tracking to reflect transaction loss
- $this->mTrxLevel = 0;
- $this->mTrxIdleCallbacks = []; // bug 65263
- $this->mTrxPreCommitCallbacks = []; // bug 65263
- wfDebug( "Connection lost, reconnecting...\n" );
- # Stash the last error values since ping() might clear them
+ $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
+ # Stash the last error values before anything might clear them
$lastError = $this->lastError();
$lastErrno = $this->lastErrno();
- if ( $this->ping() ) {
+ # Update state tracking to reflect transaction loss due to disconnection
+ $this->handleTransactionLoss();
+ wfDebug( "Connection lost, reconnecting...\n" );
+ if ( $this->reconnect() ) {
wfDebug( "Reconnected\n" );
- $server = $this->getServer();
- $msg = __METHOD__ . ": lost connection to $server; reconnected";
+ $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
- if ( ( $hadTrx && !$isNoopCommit ) || $this->mNamedLocksHeld ) {
- # Leave $ret as false and let an error be reported.
- # Callers may catch the exception and continue to use the DB.
- $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
+ if ( !$recoverable ) {
+ # Callers may catch the exception and continue to use the DB
+ $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
} else {
- # Should be safe to silently retry (no trx/callbacks/locks)
+ # Should be safe to silently retry the query
$startTime = microtime( true );
$ret = $this->doQuery( $commentedSql );
$queryRuntime = microtime( true ) - $startTime;
}
if ( false === $ret ) {
+ # Deadlocks cause the entire transaction to abort, not just the statement.
+ # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
+ # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
+ if ( $this->wasDeadlock() ) {
+ if ( $this->explicitTrxActive() || $priorWritesPending ) {
+ $tempIgnore = false; // not recoverable
+ }
+ # Update state tracking to reflect transaction loss
+ $this->handleTransactionLoss();
+ }
+
$this->reportQueryError(
$this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
}
return $res;
}
+ private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
+ # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
+ # Dropped connections also mean that named locks are automatically released.
+ # Only allow error suppression in autocommit mode or when the lost transaction
+ # didn't matter anyway (aside from DBO_TRX snapshot loss).
+ if ( $this->mNamedLocksHeld ) {
+ return false; // possible critical section violation
+ } elseif ( $sql === 'COMMIT' ) {
+ return !$priorWritesPending; // nothing written anyway? (T127428)
+ } elseif ( $sql === 'ROLLBACK' ) {
+ return true; // transaction lost...which is also what was requested :)
+ } elseif ( $this->explicitTrxActive() ) {
+ return false; // don't drop atomocity
+ } elseif ( $priorWritesPending ) {
+ return false; // prior writes lost from implicit transaction
+ }
+
+ return true;
+ }
+
+ private function handleTransactionLoss() {
+ $this->mTrxLevel = 0;
+ $this->mTrxIdleCallbacks = []; // bug 65263
+ $this->mTrxPreCommitCallbacks = []; // bug 65263
+ try {
+ // Handle callbacks in mTrxEndCallbacks
+ $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
+ return null;
+ } catch ( Exception $e ) {
+ // Already logged; move on...
+ return $e;
+ }
+ }
+
public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
if ( $this->ignoreErrors() || $tempIgnore ) {
wfDebug( "SQL ERROR (ignored): $error\n" );
*
* @param integer $trigger IDatabase::TRIGGER_* constant
* @since 1.20
+ * @throws Exception
*/
public function runOnTransactionIdleCallbacks( $trigger ) {
if ( $this->suppressPostCommitCallbacks ) {
}
$autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
-
+ /** @var Exception $e */
$e = $ePrior = null; // last exception
do { // callbacks may add callbacks :)
$callbacks = array_merge(
wfWarn( "$fname: No transaction to commit, something got out of sync!" );
return; // nothing to do
} elseif ( $this->mTrxAutomatic ) {
- wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
+ throw new DBUnexpectedError(
+ $this,
+ "$fname: Explicit commit of implicit transaction."
+ );
}
}
*/
protected function doRollback( $fname ) {
if ( $this->mTrxLevel ) {
- $this->query( 'ROLLBACK', $fname, true );
+ # Disconnects cause rollback anyway, so ignore those errors
+ $ignoreErrors = true;
+ $this->query( 'ROLLBACK', $fname, $ignoreErrors );
$this->mTrxLevel = 0;
}
}
+ /**
+ * @return bool
+ */
+ protected function explicitTrxActive() {
+ return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
+ }
+
/**
* Creates a new table with structure copied from existing table
* Note that unlike most database abstraction functions, this function does not
}
public function ping() {
+ try {
+ // This will reconnect if possible, or error out if not
+ $this->query( "SELECT 1 AS ping", __METHOD__ );
+ return true;
+ } catch ( DBError $e ) {
+ return false;
+ }
+ }
+
+ /**
+ * @return bool
+ */
+ protected function reconnect() {
# Stub. Not essential to override.
return true;
}
dépôts / lhc / web / wiklou.git / commitdiff