org.neo4j.driver.internal.cluster.SingleDatabaseRoutingProcedureRunner Maven / Gradle / Ivy

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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.neo4j.driver.internal.cluster;

import java.util.List;
import java.util.concurrent.CompletionException;
import java.util.concurrent.CompletionStage;

import org.neo4j.driver.AccessMode;
import org.neo4j.driver.Bookmark;
import org.neo4j.driver.Query;
import org.neo4j.driver.Record;
import org.neo4j.driver.TransactionConfig;
import org.neo4j.driver.async.ResultCursor;
import org.neo4j.driver.exceptions.ClientException;
import org.neo4j.driver.exceptions.FatalDiscoveryException;
import org.neo4j.driver.internal.BookmarkHolder;
import org.neo4j.driver.internal.DatabaseName;
import org.neo4j.driver.internal.async.connection.DirectConnection;
import org.neo4j.driver.internal.spi.Connection;
import org.neo4j.driver.internal.util.Futures;
import org.neo4j.driver.internal.util.ServerVersion;

import static org.neo4j.driver.Values.parameters;
import static org.neo4j.driver.internal.DatabaseNameUtil.defaultDatabase;
import static org.neo4j.driver.internal.handlers.pulln.FetchSizeUtil.UNLIMITED_FETCH_SIZE;

/**
 * This implementation of the {@link RoutingProcedureRunner} works with single database versions of Neo4j calling
 * the procedure `dbms.cluster.routing.getRoutingTable`
 */
public class SingleDatabaseRoutingProcedureRunner implements RoutingProcedureRunner
{
    static final String ROUTING_CONTEXT = "context";
    static final String GET_ROUTING_TABLE = "CALL dbms.cluster.routing.getRoutingTable($" + ROUTING_CONTEXT + ")";

    final RoutingContext context;

    public SingleDatabaseRoutingProcedureRunner( RoutingContext context )
    {
        this.context = context;
    }

    @Override
    public CompletionStage run( Connection connection, DatabaseName databaseName, Bookmark bookmark, String impersonatedUser )
    {
        DirectConnection delegate = connection( connection );
        Query procedure = procedureQuery( connection.serverVersion(), databaseName );
        BookmarkHolder bookmarkHolder = bookmarkHolder( bookmark );
        return runProcedure( delegate, procedure, bookmarkHolder )
                .thenCompose( records -> releaseConnection( delegate, records ) )
                .handle( ( records, error ) -> processProcedureResponse( procedure, records, error ) );
    }

    DirectConnection connection( Connection connection )
    {
        return new DirectConnection( connection, defaultDatabase(), AccessMode.WRITE, null );
    }

    Query procedureQuery(ServerVersion serverVersion, DatabaseName databaseName )
    {
        if ( databaseName.databaseName().isPresent() )
        {
            throw new FatalDiscoveryException( String.format(
                    "Refreshing routing table for multi-databases is not supported in server version lower than 4.0. " +
                            "Current server version: %s. Database name: '%s'", serverVersion, databaseName.description() ) );
        }
        return new Query( GET_ROUTING_TABLE, parameters( ROUTING_CONTEXT, context.toMap() ) );
    }

    BookmarkHolder bookmarkHolder( Bookmark ignored )
    {
        return BookmarkHolder.NO_OP;
    }

    CompletionStage> runProcedure(Connection connection, Query procedure, BookmarkHolder bookmarkHolder )
    {
        return connection.protocol()
                         .runInAutoCommitTransaction( connection, procedure, bookmarkHolder, TransactionConfig.empty(), UNLIMITED_FETCH_SIZE )
                         .asyncResult().thenCompose( ResultCursor::listAsync );
    }

    private CompletionStage> releaseConnection( Connection connection, List records )
    {
        // It is not strictly required to release connection after routing procedure invocation because it'll
        // be released by the PULL_ALL response handler after result is fully fetched. Such release will happen
        // in background. However, releasing it early as part of whole chain makes it easier to reason about
        // rediscovery in stub server tests. Some of them assume connections to instances not present in new
        // routing table will be closed immediately.
        return connection.release().thenApply( ignore -> records );
    }

    private static RoutingProcedureResponse processProcedureResponse(Query procedure, List records,
                                                                     Throwable error )
    {
        Throwable cause = Futures.completionExceptionCause( error );
        if ( cause != null )
        {
            return handleError( procedure, cause );
        }
        else
        {
            return new RoutingProcedureResponse( procedure, records );
        }
    }

    private static RoutingProcedureResponse handleError(Query procedure, Throwable error )
    {
        if ( error instanceof ClientException )
        {
            return new RoutingProcedureResponse( procedure, error );
        }
        else
        {
            throw new CompletionException( error );
        }
    }
}