org.h2.mvstore.tx.RollbackDecisionMaker Maven / Gradle / Ivy
/*
* Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.mvstore.tx;
import org.h2.mvstore.MVMap;
import org.h2.value.VersionedValue;
/**
* Class RollbackDecisionMaker process undo log record during transaction rollback.
*
* @author Andrei Tokar
*/
final class RollbackDecisionMaker extends MVMap.DecisionMaker {
private final TransactionStore store;
private final long transactionId;
private final long toLogId;
private final TransactionStore.RollbackListener listener;
private MVMap.Decision decision;
RollbackDecisionMaker(TransactionStore store, long transactionId, long toLogId,
TransactionStore.RollbackListener listener) {
this.store = store;
this.transactionId = transactionId;
this.toLogId = toLogId;
this.listener = listener;
}
@Override
public MVMap.Decision decide(Object[] existingValue, Object[] providedValue) {
assert decision == null;
if (existingValue == null) {
// normally existingValue will always be there except of db initialization
// where some undo log entry was captured on disk but actual map entry was not
decision = MVMap.Decision.ABORT;
} else {
VersionedValue valueToRestore = (VersionedValue) existingValue[2];
long operationId;
if (valueToRestore == null ||
(operationId = valueToRestore.getOperationId()) == 0 ||
TransactionStore.getTransactionId(operationId) == transactionId
&& TransactionStore.getLogId(operationId) < toLogId) {
int mapId = (Integer) existingValue[0];
MVMap map = store.openMap(mapId);
if (map != null && !map.isClosed()) {
Object key = existingValue[1];
VersionedValue previousValue = map.operate(key, valueToRestore, MVMap.DecisionMaker.DEFAULT);
listener.onRollback(map, key, previousValue, valueToRestore);
}
}
decision = MVMap.Decision.REMOVE;
}
return decision;
}
@Override
public void reset() {
decision = null;
}
@Override
public String toString() {
return "rollback-" + transactionId;
}
}