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ConstraintIndexCreator.java
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ConstraintIndexCreator.java
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/*
* Copyright (c) 2002-2019 "Neo4j,"
* Neo4j Sweden AB [http://neo4j.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.api.state;
import java.io.IOException;
import java.util.function.Supplier;
import org.neo4j.internal.kernel.api.IndexReference;
import org.neo4j.internal.kernel.api.Kernel;
import org.neo4j.internal.kernel.api.SchemaRead;
import org.neo4j.internal.kernel.api.TokenRead;
import org.neo4j.internal.kernel.api.Transaction;
import org.neo4j.internal.kernel.api.exceptions.TransactionFailureException;
import org.neo4j.internal.kernel.api.exceptions.schema.CreateConstraintFailureException;
import org.neo4j.internal.kernel.api.exceptions.schema.IndexNotFoundKernelException;
import org.neo4j.internal.kernel.api.exceptions.schema.SchemaKernelException;
import org.neo4j.internal.kernel.api.exceptions.schema.SchemaKernelException.OperationContext;
import org.neo4j.internal.kernel.api.schema.SchemaDescriptor;
import org.neo4j.kernel.api.KernelTransaction;
import org.neo4j.kernel.api.SilentTokenNameLookup;
import org.neo4j.kernel.api.Statement;
import org.neo4j.kernel.api.exceptions.index.IndexEntryConflictException;
import org.neo4j.kernel.api.exceptions.index.IndexPopulationFailedKernelException;
import org.neo4j.kernel.api.exceptions.schema.AlreadyConstrainedException;
import org.neo4j.kernel.api.exceptions.schema.AlreadyIndexedException;
import org.neo4j.kernel.api.exceptions.schema.UniquePropertyValueValidationException;
import org.neo4j.storageengine.api.NodePropertyAccessor;
import org.neo4j.kernel.api.schema.constraints.ConstraintDescriptorFactory;
import org.neo4j.kernel.api.schema.constraints.UniquenessConstraintDescriptor;
import org.neo4j.kernel.impl.api.KernelTransactionImplementation;
import org.neo4j.kernel.impl.api.index.IndexProxy;
import org.neo4j.kernel.impl.api.index.IndexingService;
import org.neo4j.kernel.impl.locking.Locks.Client;
import org.neo4j.logging.Log;
import org.neo4j.logging.LogProvider;
import org.neo4j.storageengine.api.schema.IndexDescriptor;
import static org.neo4j.internal.kernel.api.Transaction.Type.implicit;
import static org.neo4j.internal.kernel.api.exceptions.schema.ConstraintValidationException.Phase.VERIFICATION;
import static org.neo4j.internal.kernel.api.exceptions.schema.SchemaKernelException.OperationContext.CONSTRAINT_CREATION;
import static org.neo4j.internal.kernel.api.security.SecurityContext.AUTH_DISABLED;
public class ConstraintIndexCreator
{
private final IndexingService indexingService;
private final Supplier<Kernel> kernelSupplier;
private final NodePropertyAccessor nodePropertyAccessor;
private final Log log;
public ConstraintIndexCreator( Supplier<Kernel> kernelSupplier, IndexingService indexingService,
NodePropertyAccessor nodePropertyAccessor, LogProvider logProvider )
{
this.kernelSupplier = kernelSupplier;
this.indexingService = indexingService;
this.nodePropertyAccessor = nodePropertyAccessor;
this.log = logProvider.getLog( ConstraintIndexCreator.class );
}
/**
* You MUST hold a label write lock before you call this method.
* However the label write lock is temporarily released while populating the index backing the constraint.
* It goes a little like this:
* <ol>
* <li>Prerequisite: Getting here means that there's an open schema transaction which has acquired the
* LABEL WRITE lock.</li>
* <li>Index schema rule which is backing the constraint is created in a nested mini-transaction
* which doesn't acquire any locking, merely adds tx state and commits so that the index rule is applied
* to the store, which triggers the index population</li>
* <li>Release the LABEL WRITE lock</li>
* <li>Await index population to complete</li>
* <li>Acquire the LABEL WRITE lock (effectively blocking concurrent transactions changing
* data related to this constraint, and it so happens, most other transactions as well) and verify
* the uniqueness of the built index</li>
* <li>Leave this method, knowing that the uniqueness constraint rule will be added to tx state
* and this tx committed, which will create the uniqueness constraint</li>
* </ol>
*/
public long createUniquenessConstraintIndex( KernelTransactionImplementation transaction, SchemaDescriptor descriptor, String provider )
throws TransactionFailureException, CreateConstraintFailureException,
UniquePropertyValueValidationException, AlreadyConstrainedException
{
UniquenessConstraintDescriptor constraint = ConstraintDescriptorFactory.uniqueForSchema( descriptor );
log.info( "Starting constraint creation: %s.", constraint.ownedIndexDescriptor() );
IndexReference index;
SchemaRead schemaRead = transaction.schemaRead();
try
{
index = getOrCreateUniquenessConstraintIndex( schemaRead, transaction.tokenRead(), descriptor, provider );
}
catch ( AlreadyConstrainedException e )
{
throw e;
}
catch ( SchemaKernelException | IndexNotFoundKernelException e )
{
throw new CreateConstraintFailureException( constraint, e );
}
boolean success = false;
boolean reacquiredLabelLock = false;
Client locks = transaction.statementLocks().pessimistic();
try
{
long indexId = schemaRead.indexGetCommittedId( index );
IndexProxy proxy = indexingService.getIndexProxy( indexId );
// Release the LABEL WRITE lock during index population.
// At this point the integrity of the constraint to be created was checked
// while holding the lock and the index rule backing the soon-to-be-created constraint
// has been created. Now it's just the population left, which can take a long time
locks.releaseExclusive( descriptor.keyType(), descriptor.keyId() );
awaitConstrainIndexPopulation( constraint, proxy );
log.info( "Constraint %s populated, starting verification.", constraint.ownedIndexDescriptor() );
// Index population was successful, but at this point we don't know if the uniqueness constraint holds.
// Acquire LABEL WRITE lock and verify the constraints here in this user transaction
// and if everything checks out then it will be held until after the constraint has been
// created and activated.
locks.acquireExclusive( transaction.lockTracer(), descriptor.keyType(), descriptor.keyId() );
reacquiredLabelLock = true;
indexingService.getIndexProxy( indexId ).verifyDeferredConstraints( nodePropertyAccessor );
log.info( "Constraint %s verified.", constraint.ownedIndexDescriptor() );
success = true;
return indexId;
}
catch ( SchemaKernelException e )
{
throw new IllegalStateException(
String.format( "Index (%s) that we just created does not exist.", descriptor ), e );
}
catch ( IndexNotFoundKernelException e )
{
throw new TransactionFailureException(
String.format( "Index (%s) that we just created does not exist.", descriptor ), e );
}
catch ( IndexEntryConflictException e )
{
throw new UniquePropertyValueValidationException( constraint, VERIFICATION, e );
}
catch ( InterruptedException | IOException e )
{
throw new CreateConstraintFailureException( constraint, e );
}
finally
{
if ( !success )
{
if ( !reacquiredLabelLock )
{
locks.acquireExclusive( transaction.lockTracer(), descriptor.keyType(), descriptor.keyId() );
}
if ( indexStillExists( schemaRead, descriptor, index ) )
{
dropUniquenessConstraintIndex( (IndexDescriptor) index );
}
}
}
}
private boolean indexStillExists( SchemaRead schemaRead, SchemaDescriptor descriptor, IndexReference index )
{
IndexReference existingIndex = schemaRead.index( descriptor );
return existingIndex != IndexReference.NO_INDEX && existingIndex.equals( index );
}
/**
* You MUST hold a schema write lock before you call this method.
*/
public void dropUniquenessConstraintIndex( IndexDescriptor descriptor )
throws TransactionFailureException
{
try ( Transaction transaction = kernelSupplier.get().beginTransaction( implicit, AUTH_DISABLED );
Statement ignore = ((KernelTransaction)transaction).acquireStatement() )
{
((KernelTransactionImplementation) transaction).txState().indexDoDrop( descriptor );
transaction.success();
}
}
private void awaitConstrainIndexPopulation( UniquenessConstraintDescriptor constraint, IndexProxy proxy )
throws InterruptedException, UniquePropertyValueValidationException
{
try
{
proxy.awaitStoreScanCompleted();
}
catch ( IndexPopulationFailedKernelException e )
{
Throwable cause = e.getCause();
if ( cause instanceof IndexEntryConflictException )
{
throw new UniquePropertyValueValidationException(
constraint, VERIFICATION, (IndexEntryConflictException) cause );
}
else
{
throw new UniquePropertyValueValidationException( constraint, VERIFICATION, e );
}
}
}
private IndexReference getOrCreateUniquenessConstraintIndex( SchemaRead schemaRead, TokenRead tokenRead, SchemaDescriptor schema, String provider )
throws SchemaKernelException, IndexNotFoundKernelException
{
IndexReference descriptor = schemaRead.index( schema );
if ( descriptor != IndexReference.NO_INDEX )
{
if ( descriptor.isUnique() )
{
// OK so we found a matching constraint index. We check whether or not it has an owner
// because this may have been a left-over constraint index from a previously failed
// constraint creation, due to crash or similar, hence the missing owner.
if ( schemaRead.indexGetOwningUniquenessConstraintId( descriptor ) == null )
{
return descriptor;
}
throw new AlreadyConstrainedException(
ConstraintDescriptorFactory.uniqueForSchema( schema ),
OperationContext.CONSTRAINT_CREATION,
new SilentTokenNameLookup( tokenRead ) );
}
// There's already an index for this schema descriptor, which isn't of the type we're after.
throw new AlreadyIndexedException( schema, CONSTRAINT_CREATION );
}
IndexDescriptor indexDescriptor = createConstraintIndex( schema, provider );
IndexProxy indexProxy = indexingService.getIndexProxy( indexDescriptor.schema() );
return indexProxy.getDescriptor();
}
public IndexDescriptor createConstraintIndex( final SchemaDescriptor schema, String provider )
{
try ( Transaction transaction = kernelSupplier.get().beginTransaction( implicit, AUTH_DISABLED ) )
{
IndexDescriptor index = ((KernelTransaction) transaction).indexUniqueCreate( schema, provider );
transaction.success();
return index;
}
catch ( TransactionFailureException | SchemaKernelException e )
{
throw new RuntimeException( e );
}
}
}