org.neo4j.driver.internal.async.pool.NettyChannelTracker 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.pool;

import static org.neo4j.driver.internal.async.connection.ChannelAttributes.poolId;
import static org.neo4j.driver.internal.async.connection.ChannelAttributes.serverAddress;

import io.netty.channel.Channel;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.channel.pool.ChannelPoolHandler;
import io.netty.util.concurrent.EventExecutor;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.Supplier;
import org.neo4j.driver.Logger;
import org.neo4j.driver.Logging;
import org.neo4j.driver.internal.BoltServerAddress;
import org.neo4j.driver.internal.messaging.BoltProtocol;
import org.neo4j.driver.internal.metrics.ListenerEvent;
import org.neo4j.driver.internal.metrics.MetricsListener;
import org.neo4j.driver.net.ServerAddress;

public class NettyChannelTracker implements ChannelPoolHandler {
    private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
    private final Lock read = lock.readLock();
    private final Lock write = lock.writeLock();
    private final Map addressToInUseChannelCount = new HashMap<>();
    private final Map addressToIdleChannelCount = new HashMap<>();
    private final Logger log;
    private final MetricsListener metricsListener;
    private final ChannelFutureListener closeListener = future -> channelClosed(future.channel());
    private final ChannelGroup allChannels;

    public NettyChannelTracker(MetricsListener metricsListener, EventExecutor eventExecutor, Logging logging) {
        this(metricsListener, new DefaultChannelGroup("all-connections", eventExecutor), logging);
    }

    public NettyChannelTracker(MetricsListener metricsListener, ChannelGroup channels, Logging logging) {
        this.metricsListener = metricsListener;
        this.log = logging.getLog(getClass());
        this.allChannels = channels;
    }

    private void doInWriteLock(Runnable work) {
        try {
            write.lock();
            work.run();
        } finally {
            write.unlock();
        }
    }

    private  T retrieveInReadLock(Supplier work) {
        try {
            read.lock();
            return work.get();
        } finally {
            read.unlock();
        }
    }

    @Override
    public void channelReleased(Channel channel) {
        doInWriteLock(() -> {
            decrementInUse(channel);
            incrementIdle(channel);
            channel.closeFuture().addListener(closeListener);
        });

        log.debug("Channel [0x%s] released back to the pool", channel.id());
    }

    @Override
    public void channelAcquired(Channel channel) {
        doInWriteLock(() -> {
            incrementInUse(channel);
            decrementIdle(channel);
            channel.closeFuture().removeListener(closeListener);
        });

        log.debug(
                "Channel [0x%s] acquired from the pool. Local address: %s, remote address: %s",
                channel.id(), channel.localAddress(), channel.remoteAddress());
    }

    @Override
    public void channelCreated(Channel channel) {
        throw new IllegalStateException("Untraceable channel created.");
    }

    public void channelCreated(Channel channel, ListenerEvent creatingEvent) {
        // when it is created, we count it as idle as it has not been acquired out of the pool
        doInWriteLock(() -> incrementIdle(channel));

        metricsListener.afterCreated(poolId(channel), creatingEvent);
        allChannels.add(channel);
        log.debug(
                "Channel [0x%s] created. Local address: %s, remote address: %s",
                channel.id(), channel.localAddress(), channel.remoteAddress());
    }

    public ListenerEvent channelCreating(String poolId) {
        ListenerEvent creatingEvent = metricsListener.createListenerEvent();
        metricsListener.beforeCreating(poolId, creatingEvent);
        return creatingEvent;
    }

    public void channelFailedToCreate(String poolId) {
        metricsListener.afterFailedToCreate(poolId);
    }

    public void channelClosed(Channel channel) {
        doInWriteLock(() -> decrementIdle(channel));
        metricsListener.afterClosed(poolId(channel));
    }

    public int inUseChannelCount(ServerAddress address) {
        return retrieveInReadLock(() -> addressToInUseChannelCount.getOrDefault(address, 0));
    }

    public int idleChannelCount(ServerAddress address) {
        return retrieveInReadLock(() -> addressToIdleChannelCount.getOrDefault(address, 0));
    }

    public void prepareToCloseChannels() {
        for (Channel channel : allChannels) {
            BoltProtocol protocol = BoltProtocol.forChannel(channel);
            try {
                protocol.prepareToCloseChannel(channel);
            } catch (Throwable e) {
                // only logging it
                log.debug(
                        "Failed to prepare to close Channel %s due to error %s. "
                                + "It is safe to ignore this error as the channel will be closed despite if it is successfully prepared to close or not.",
                        channel, e.getMessage());
            }
        }
    }

    private void incrementInUse(Channel channel) {
        increment(channel, addressToInUseChannelCount);
    }

    private void decrementInUse(Channel channel) {
        BoltServerAddress address = serverAddress(channel);
        if (!addressToInUseChannelCount.containsKey(address)) {
            throw new IllegalStateException("No count exists for address '" + address + "' in the 'in use' count");
        }
        Integer count = addressToInUseChannelCount.get(address);
        addressToInUseChannelCount.put(address, count - 1);
    }

    private void incrementIdle(Channel channel) {
        increment(channel, addressToIdleChannelCount);
    }

    private void decrementIdle(Channel channel) {
        BoltServerAddress address = serverAddress(channel);
        if (!addressToIdleChannelCount.containsKey(address)) {
            throw new IllegalStateException("No count exists for address '" + address + "' in the 'idle' count");
        }
        Integer count = addressToIdleChannelCount.get(address);
        addressToIdleChannelCount.put(address, count - 1);
    }

    private void increment(Channel channel, Map countMap) {
        ServerAddress address = serverAddress(channel);
        Integer count = countMap.computeIfAbsent(address, k -> 0);
        countMap.put(address, count + 1);
    }
}