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RecoverConsensusLogIndex.java
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RecoverConsensusLogIndex.java
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/*
* Copyright (c) 2002-2018 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.causalclustering.core.state.machines.tx;
import org.neo4j.kernel.impl.transaction.log.LogicalTransactionStore;
import org.neo4j.kernel.impl.transaction.log.TransactionIdStore;
import org.neo4j.kernel.impl.util.Dependencies;
import org.neo4j.logging.LogProvider;
import static org.neo4j.graphdb.DependencyResolver.SelectionStrategy.ONLY;
/**
* Retrieves last raft log index that was appended to the transaction log, so that raft log replay can recover while
* preserving idempotency (avoid appending the same transaction twice).
*/
public class RecoverConsensusLogIndex
{
private final Dependencies dependencies;
private final LogProvider logProvider;
public RecoverConsensusLogIndex( Dependencies dependencies, LogProvider logProvider )
{
this.dependencies = dependencies;
this.logProvider = logProvider;
}
public long findLastAppliedIndex()
{
TransactionIdStore transactionIdStore = dependencies.resolveDependency( TransactionIdStore.class, ONLY );
LogicalTransactionStore transactionStore = dependencies.resolveDependency( LogicalTransactionStore.class, ONLY );
return new LastCommittedIndexFinder( transactionIdStore, transactionStore, logProvider )
.getLastCommittedIndex();
}
}