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Wait for current leader to become available in RaftReplicator
Previously we have used a logic where we send to last known leader. In this commit RaftReplicator will wait indefinitely for a valid leader and will not try to resend the request to an out of date member.
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...-clustering/src/main/java/org/neo4j/causalclustering/core/replication/LeaderProvider.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,56 @@ | ||
| /* | ||
| * Copyright (c) 2002-2018 "Neo4j," | ||
| * Neo4j Sweden AB [http://neo4j.com] | ||
| * | ||
| * This file is part of Neo4j Enterprise Edition. The included source | ||
| * code can be redistributed and/or modified under the terms of the | ||
| * GNU AFFERO GENERAL PUBLIC LICENSE Version 3 | ||
| * (http://www.fsf.org/licensing/licenses/agpl-3.0.html) with the | ||
| * Commons Clause, as found in the associated LICENSE.txt file. | ||
| * | ||
| * 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. | ||
| * | ||
| * Neo4j object code can be licensed independently from the source | ||
| * under separate terms from the AGPL. Inquiries can be directed to: | ||
| * licensing@neo4j.com | ||
| * | ||
| * More information is also available at: | ||
| * https://neo4j.com/licensing/ | ||
| */ | ||
| package org.neo4j.causalclustering.core.replication; | ||
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|
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| import org.neo4j.causalclustering.identity.MemberId; | ||
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| class LeaderProvider | ||
| { | ||
| private MemberId currentLeader; | ||
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| synchronized MemberId awaitLeader() throws InterruptedException | ||
| { | ||
| if ( currentLeader == null ) | ||
| { | ||
| while ( currentLeader == null ) | ||
| { | ||
| wait( ); | ||
| } | ||
| } | ||
| return currentLeader; | ||
| } | ||
|
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| synchronized void setLeader( MemberId leader ) | ||
| { | ||
| this.currentLeader = leader; | ||
| if ( currentLeader != null ) | ||
| { | ||
| notifyAll(); | ||
| } | ||
| } | ||
|
|
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| MemberId currentLeader() | ||
| { | ||
| return currentLeader; | ||
| } | ||
| } |
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...stering/src/test/java/org/neo4j/causalclustering/core/replication/LeaderProviderTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,111 @@ | ||
| /* | ||
| * Copyright (c) 2002-2018 "Neo4j," | ||
| * Neo4j Sweden AB [http://neo4j.com] | ||
| * | ||
| * This file is part of Neo4j Enterprise Edition. The included source | ||
| * code can be redistributed and/or modified under the terms of the | ||
| * GNU AFFERO GENERAL PUBLIC LICENSE Version 3 | ||
| * (http://www.fsf.org/licensing/licenses/agpl-3.0.html) with the | ||
| * Commons Clause, as found in the associated LICENSE.txt file. | ||
| * | ||
| * 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. | ||
| * | ||
| * Neo4j object code can be licensed independently from the source | ||
| * under separate terms from the AGPL. Inquiries can be directed to: | ||
| * licensing@neo4j.com | ||
| * | ||
| * More information is also available at: | ||
| * https://neo4j.com/licensing/ | ||
| */ | ||
| package org.neo4j.causalclustering.core.replication; | ||
|
|
||
| import org.junit.Before; | ||
| import org.junit.Test; | ||
|
|
||
| import java.util.ArrayList; | ||
| import java.util.List; | ||
| import java.util.UUID; | ||
| import java.util.concurrent.Callable; | ||
| import java.util.concurrent.ExecutionException; | ||
| import java.util.concurrent.ExecutorService; | ||
| import java.util.concurrent.Executors; | ||
| import java.util.concurrent.Future; | ||
| import java.util.concurrent.TimeUnit; | ||
| import java.util.concurrent.TimeoutException; | ||
|
|
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| import org.neo4j.causalclustering.identity.MemberId; | ||
| import org.neo4j.util.concurrent.Futures; | ||
|
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| import static org.junit.Assert.assertEquals; | ||
| import static org.junit.Assert.assertFalse; | ||
| import static org.junit.Assert.assertNull; | ||
| import static org.junit.Assert.assertTrue; | ||
|
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| public class LeaderProviderTest | ||
| { | ||
|
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| private static final MemberId MEMBER_ID = new MemberId( UUID.randomUUID() ); | ||
| private final ExecutorService executorService = Executors.newCachedThreadPool(); | ||
| private final LeaderProvider leaderProvider = new LeaderProvider(); | ||
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| @Before | ||
| public void before() | ||
| { | ||
| leaderProvider.setLeader( null ); | ||
| } | ||
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| @Test | ||
| public void shouldGiveCurrentLeaderIfAvailable() throws InterruptedException | ||
| { | ||
| leaderProvider.setLeader( MEMBER_ID ); | ||
| assertEquals( leaderProvider.currentLeader(), MEMBER_ID ); | ||
| assertEquals( leaderProvider.awaitLeader(), MEMBER_ID ); | ||
| } | ||
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| @Test | ||
| public void shouldWaitForNonNullValue() throws InterruptedException, ExecutionException, TimeoutException | ||
| { | ||
| // given | ||
| int threads = 3; | ||
| assertNull( leaderProvider.currentLeader() ); | ||
|
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| // when | ||
| List<Future<MemberId>> futures = new ArrayList<>(); | ||
| for ( int i = 0; i < threads; i++ ) | ||
| { | ||
| Future<MemberId> interrupted = executorService.submit( getCurrentLeader() ); | ||
| futures.add( interrupted ); | ||
| } | ||
|
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| // then | ||
| Future<List<MemberId>> combine = Futures.combine( futures ); | ||
| Thread.sleep( 100 ); | ||
| assertFalse( combine.isDone() ); | ||
|
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| // when | ||
| leaderProvider.setLeader( MEMBER_ID ); | ||
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| List<MemberId> memberIds = combine.get( 5, TimeUnit.SECONDS ); | ||
|
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| // then | ||
| assertTrue( memberIds.stream().allMatch( memberId -> memberId.equals( MEMBER_ID ) ) ); | ||
| } | ||
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| private Callable<MemberId> getCurrentLeader() | ||
| { | ||
| return () -> | ||
| { | ||
| try | ||
| { | ||
| return leaderProvider.awaitLeader(); | ||
| } | ||
| catch ( InterruptedException e ) | ||
| { | ||
| throw new RuntimeException( "Interrupted" ); | ||
| } | ||
| }; | ||
| } | ||
| } |
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