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CheckPointerConstraintCreationDeadlockIT.java
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CheckPointerConstraintCreationDeadlockIT.java
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/*
* Copyright (c) 2002-2017 "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 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.transaction.log.checkpoint;
import org.junit.Rule;
import org.junit.Test;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Future;
import org.neo4j.graphdb.Label;
import org.neo4j.graphdb.Transaction;
import org.neo4j.kernel.api.exceptions.TransactionFailureException;
import org.neo4j.kernel.impl.api.TransactionCommitProcess;
import org.neo4j.kernel.impl.api.TransactionToApply;
import org.neo4j.kernel.impl.api.index.IndexingService;
import org.neo4j.kernel.impl.locking.LockWrapper;
import org.neo4j.kernel.impl.transaction.TransactionRepresentation;
import org.neo4j.kernel.impl.transaction.log.LogicalTransactionStore;
import org.neo4j.kernel.impl.transaction.log.TransactionCursor;
import org.neo4j.kernel.impl.transaction.log.TransactionIdStore;
import org.neo4j.kernel.internal.GraphDatabaseAPI;
import org.neo4j.kernel.monitoring.Monitors;
import org.neo4j.test.Barrier;
import org.neo4j.test.EphemeralFileSystemRule;
import org.neo4j.test.OtherThreadRule;
import org.neo4j.test.TestGraphDatabaseFactory;
import org.neo4j.test.TestLabels;
import static java.util.concurrent.TimeUnit.SECONDS;
import static org.neo4j.kernel.impl.transaction.tracing.CommitEvent.NULL;
import static org.neo4j.storageengine.api.TransactionApplicationMode.EXTERNAL;
/**
* The scenario, which takes place on database instance applying constraint
* creation as an external transaction, looks like this:
*
* <ol>
* <li>
* Transaction T1 creates the constraint index and population P starts
* </li>
* <li>
* Transaction T2 which activates the constraint starts applying and now has a read lock on the counts store
* </li>
* <li>
* Check point triggers, wants to rotate counts store and so acquires its write lock.
* It will have to block, but doing so will also blocks further read lock requests
* </li>
* <li>
* T2 moves on to activate the constraint. Doing so means first waiting for the index to come online
* </li>
* <li>
* P moves on to flip after population, something which includes initializing some sample data in counts store
* for this index. Will block on the counts store read lock, completing the deadlock
* </li>
* </ol>
*/
public class CheckPointerConstraintCreationDeadlockIT
{
private static final Label LABEL = TestLabels.LABEL_ONE;
private static final String KEY = "key";
@Rule
public final EphemeralFileSystemRule fs = new EphemeralFileSystemRule();
@Rule
public final OtherThreadRule<Void> t2 = new OtherThreadRule<>( "T2" );
@Rule
public final OtherThreadRule<Void> t3 = new OtherThreadRule<>( "T3" );
@Test
public void shouldNotDeadlock() throws Exception
{
List<TransactionRepresentation> transactions = createConstraintCreatingTransactions();
Monitors monitors = new Monitors();
GraphDatabaseAPI db = (GraphDatabaseAPI) new TestGraphDatabaseFactory()
.setMonitors( monitors ).newImpermanentDatabase();
Barrier.Control controller = new Barrier.Control();
boolean success = false;
try
{
IndexingService.Monitor monitor = new IndexingService.MonitorAdapter()
{
@Override
public void indexPopulationScanComplete()
{
controller.reached();
}
};
monitors.addMonitorListener( monitor );
Future<Object> applier = applyInT2( db, transactions );
controller.await();
// At this point the index population has completed and the population thread is ready to
// acquire the counts store read lock for initializing some samples there. We're starting the
// check pointer, which will eventually put itself in queue for acquiring the write lock
Future<Object> checkPointer = t3.execute( state ->
db.getDependencyResolver().resolveDependency( CheckPointer.class )
.forceCheckPoint( new SimpleTriggerInfo( "MANUAL" ) ) );
try
{
t3.get().waitUntilWaiting( details -> details.isAt( LockWrapper.class, "writeLock" ) );
}
catch ( IllegalStateException e )
{
// Thrown when the fix is in, basically it's thrown if the check pointer didn't get blocked
checkPointer.get(); // to assert that no exception was thrown during in check point thread
}
// Alright the trap is set. Let the population thread move on and seal the deal
controller.release();
// THEN these should complete
applier.get( 10, SECONDS );
checkPointer.get( 10, SECONDS );
success = true;
}
finally
{
if ( !success )
{
t2.interrupt();
t3.interrupt();
// so that shutdown won't hang too
}
db.shutdown();
}
}
private Future<Object> applyInT2( GraphDatabaseAPI db, List<TransactionRepresentation> transactions )
{
TransactionCommitProcess commitProcess =
db.getDependencyResolver().resolveDependency( TransactionCommitProcess.class );
return t2.execute( state ->
{
transactions.forEach( tx ->
{
try
{
// It will matter if the transactions are supplied all in the same batch or one by one
// since the CountsTracker#apply lock is held and released per transaction
commitProcess.commit( new TransactionToApply( tx ), NULL, EXTERNAL );
}
catch ( TransactionFailureException e )
{
throw new RuntimeException( e );
}
} );
return null;
} );
}
private static List<TransactionRepresentation> createConstraintCreatingTransactions() throws Exception
{
GraphDatabaseAPI db = (GraphDatabaseAPI) new TestGraphDatabaseFactory().newImpermanentDatabase();
try
{
try ( Transaction tx = db.beginTx() )
{
db.schema().constraintFor( LABEL ).assertPropertyIsUnique( KEY ).create();
tx.success();
}
LogicalTransactionStore txStore = db.getDependencyResolver().resolveDependency( LogicalTransactionStore.class );
List<TransactionRepresentation> result = new ArrayList<>();
try ( TransactionCursor cursor = txStore.getTransactions( TransactionIdStore.BASE_TX_ID + 1 ) )
{
while ( cursor.next() )
{
result.add( cursor.get().getTransactionRepresentation() );
}
}
return result;
}
finally
{
db.shutdown();
}
}
}