org.neo4j.driver.internal.async.inbound.ChannelErrorHandler Maven / Gradle / Ivy

/*
 * 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.async.inbound;

import static java.util.Objects.requireNonNull;
import static org.neo4j.driver.internal.async.connection.ChannelAttributes.messageDispatcher;
import static org.neo4j.driver.internal.async.connection.ChannelAttributes.terminationReason;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.CodecException;
import java.io.IOException;
import org.neo4j.driver.Logging;
import org.neo4j.driver.exceptions.ConnectionReadTimeoutException;
import org.neo4j.driver.exceptions.ServiceUnavailableException;
import org.neo4j.driver.internal.logging.ChannelActivityLogger;
import org.neo4j.driver.internal.logging.ChannelErrorLogger;
import org.neo4j.driver.internal.util.ErrorUtil;

public class ChannelErrorHandler extends ChannelInboundHandlerAdapter {
    private final Logging logging;

    private InboundMessageDispatcher messageDispatcher;
    private ChannelActivityLogger log;
    private ChannelErrorLogger errorLog;
    private boolean failed;

    public ChannelErrorHandler(Logging logging) {
        this.logging = logging;
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) {
        messageDispatcher = requireNonNull(messageDispatcher(ctx.channel()));
        log = new ChannelActivityLogger(ctx.channel(), logging, getClass());
        errorLog = new ChannelErrorLogger(ctx.channel(), logging);
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) {
        messageDispatcher = null;
        log = null;
        failed = false;
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) {
        log.debug("Channel is inactive");

        String terminationReason = terminationReason(ctx.channel());
        Throwable error = ErrorUtil.newConnectionTerminatedError(terminationReason);

        if (!failed) {
            // channel became inactive not because of a fatal exception that came from exceptionCaught
            // it is most likely inactive because actual network connection broke or was explicitly closed by the driver

            messageDispatcher.handleChannelInactive(error);
            ctx.channel().close();
        } else {
            fail(error);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable error) {
        if (failed) {
            errorLog.traceOrDebug("Another fatal error occurred in the pipeline", error);
        } else {
            failed = true;
            logUnexpectedErrorWarning(error);
            fail(error);
        }
    }

    private void logUnexpectedErrorWarning(Throwable error) {
        if (!(error instanceof ConnectionReadTimeoutException)) {
            errorLog.traceOrDebug("Fatal error occurred in the pipeline", error);
        }
    }

    private void fail(Throwable error) {
        Throwable cause = transformError(error);
        messageDispatcher.handleChannelError(cause);
    }

    private static Throwable transformError(Throwable error) {
        if (error instanceof CodecException && error.getCause() != null) {
            // unwrap the CodecException if it has a cause
            error = error.getCause();
        }

        if (error instanceof IOException) {
            return new ServiceUnavailableException("Connection to the database failed", error);
        } else {
            return error;
        }
    }
}