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CausalConsistencyIT.java
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CausalConsistencyIT.java
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/*
* Copyright (c) 2002-2016 "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.scenarios;
import org.junit.Rule;
import org.junit.Test;
import org.neo4j.causalclustering.catchup.tx.TxPollingClient;
import org.neo4j.causalclustering.core.CoreGraphDatabase;
import org.neo4j.causalclustering.discovery.Cluster;
import org.neo4j.causalclustering.readreplica.ReadReplicaGraphDatabase;
import org.neo4j.kernel.api.exceptions.TransactionFailureException;
import org.neo4j.kernel.api.txtracking.TransactionIdTracker;
import org.neo4j.kernel.impl.transaction.log.TransactionIdStore;
import org.neo4j.kernel.internal.GraphDatabaseAPI;
import org.neo4j.test.causalclustering.ClusterRule;
import static java.time.Duration.ofSeconds;
import static org.junit.Assert.fail;
public class CausalConsistencyIT
{
@Rule
public ClusterRule clusterRule = new ClusterRule( CausalConsistencyIT.class )
.withNumberOfCoreMembers( 3 )
.withNumberOfReadReplicas( 1 );
@Test
public void transactionsCommittedInTheCoreShouldAppearOnTheReadReplica() throws Exception
{
// given
Cluster cluster = clusterRule.startCluster();
cluster.coreTx( ( coreGraphDatabase, transaction ) -> {
coreGraphDatabase.createNode();
transaction.success();
} );
CoreGraphDatabase leaderDatabase = cluster.awaitLeader().database();
long transactionVisibleOnLeader = transactionIdTracker( leaderDatabase ).newestEncounteredTxId();
// then
ReadReplicaGraphDatabase readReplicaGraphDatabase = cluster.findAnyReadReplica().database();
transactionIdTracker( readReplicaGraphDatabase ).awaitUpToDate( transactionVisibleOnLeader, ofSeconds( 3 ) );
}
@Test
public void transactionsShouldNotAppearOnTheReadReplicaWhilePollingIsPaused() throws Exception
{
// given
Cluster cluster = clusterRule.startCluster();
ReadReplicaGraphDatabase readReplicaGraphDatabase = cluster.findAnyReadReplica().database();
TxPollingClient pollingClient = readReplicaGraphDatabase.getDependencyResolver()
.resolveDependency( TxPollingClient.class );
pollingClient.pause();
cluster.coreTx( ( coreGraphDatabase, transaction ) -> {
coreGraphDatabase.createNode();
transaction.success();
} );
CoreGraphDatabase leaderDatabase = cluster.awaitLeader().database();
long transactionVisibleOnLeader = transactionIdTracker( leaderDatabase ).newestEncounteredTxId();
// when the poller is paused, transaction doesn't make it to the read replica
try
{
transactionIdTracker( readReplicaGraphDatabase ).awaitUpToDate( transactionVisibleOnLeader, ofSeconds( 3 ) );
fail( "should have thrown exception" );
}
catch ( TransactionFailureException e )
{
// expected timeout
}
// when the poller is resumed, it does make it to the read replica
pollingClient.resume();
transactionIdTracker( readReplicaGraphDatabase ).awaitUpToDate( transactionVisibleOnLeader, ofSeconds( 3 ) );
}
private TransactionIdTracker transactionIdTracker( GraphDatabaseAPI database )
{
return new TransactionIdTracker( database
.getDependencyResolver().resolveDependency( TransactionIdStore.class ) );
}
}