connect/runtime/src/main/java/org/apache/kafka/connect/runtime/distributed/WorkerGroupMember.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.kafka.connect.runtime.distributed;

import org.apache.kafka.clients.ClientUtils;
import org.apache.kafka.clients.CommonClientConfigs;
import org.apache.kafka.clients.Metadata;
import org.apache.kafka.clients.NetworkClient;
import org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient;
import org.apache.kafka.common.Cluster;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.metrics.JmxReporter;
import org.apache.kafka.common.metrics.MetricConfig;
import org.apache.kafka.common.metrics.Metrics;
import org.apache.kafka.common.metrics.MetricsReporter;
import org.apache.kafka.common.network.ChannelBuilder;
import org.apache.kafka.common.network.Selector;
import org.apache.kafka.common.utils.AppInfoParser;
import org.apache.kafka.common.utils.Time;
import org.apache.kafka.connect.util.ConnectorTaskId;
import org.apache.kafka.connect.storage.ConfigBackingStore;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.InetSocketAddress;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

/**
 * This class manages the coordination process with brokers for the Connect cluster group membership. It ties together
 * the Coordinator, which implements the group member protocol, with all the other pieces needed to drive the connection
 * to the group coordinator broker. This isolates all the networking to a single thread managed by this class, with
 * higher level operations in response to group membership events being handled by the herder.
 */
public class WorkerGroupMember {
    private static final Logger log = LoggerFactory.getLogger(WorkerGroupMember.class);

    private static final AtomicInteger CONNECT_CLIENT_ID_SEQUENCE = new AtomicInteger(1);
    private static final String JMX_PREFIX = "kafka.connect";

    private final Time time;
    private final String clientId;
    private final ConsumerNetworkClient client;
    private final Metrics metrics;
    private final Metadata metadata;
    private final long retryBackoffMs;
    private final WorkerCoordinator coordinator;

    private boolean stopped = false;

    public WorkerGroupMember(DistributedConfig config,
                             String restUrl,
                             ConfigBackingStore configStorage,
                             WorkerRebalanceListener listener,
                             Time time) {
        try {
            this.time = time;

            String clientIdConfig = config.getString(CommonClientConfigs.CLIENT_ID_CONFIG);
            clientId = clientIdConfig.length() <= 0 ? "connect-" + CONNECT_CLIENT_ID_SEQUENCE.getAndIncrement() : clientIdConfig;
            Map<String, String> metricsTags = new LinkedHashMap<>();
            metricsTags.put("client-id", clientId);
            MetricConfig metricConfig = new MetricConfig().samples(config.getInt(CommonClientConfigs.METRICS_NUM_SAMPLES_CONFIG))
                    .timeWindow(config.getLong(CommonClientConfigs.METRICS_SAMPLE_WINDOW_MS_CONFIG), TimeUnit.MILLISECONDS)
                    .tags(metricsTags);
            List<MetricsReporter> reporters = config.getConfiguredInstances(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG, MetricsReporter.class);
            reporters.add(new JmxReporter(JMX_PREFIX));
            this.metrics = new Metrics(metricConfig, reporters, time);
            this.retryBackoffMs = config.getLong(CommonClientConfigs.RETRY_BACKOFF_MS_CONFIG);
            this.metadata = new Metadata(retryBackoffMs, config.getLong(CommonClientConfigs.METADATA_MAX_AGE_CONFIG));
            List<InetSocketAddress> addresses = ClientUtils.parseAndValidateAddresses(config.getList(CommonClientConfigs.BOOTSTRAP_SERVERS_CONFIG));
            this.metadata.update(Cluster.bootstrap(addresses), 0);
            String metricGrpPrefix = "connect";
            ChannelBuilder channelBuilder = ClientUtils.createChannelBuilder(config.values());
            NetworkClient netClient = new NetworkClient(
                    new Selector(config.getLong(CommonClientConfigs.CONNECTIONS_MAX_IDLE_MS_CONFIG), metrics, time, metricGrpPrefix, channelBuilder),
                    this.metadata,
                    clientId,
                    100, // a fixed large enough value will suffice
                    config.getLong(CommonClientConfigs.RECONNECT_BACKOFF_MS_CONFIG),
                    config.getInt(CommonClientConfigs.SEND_BUFFER_CONFIG),
                    config.getInt(CommonClientConfigs.RECEIVE_BUFFER_CONFIG),
                    config.getInt(CommonClientConfigs.REQUEST_TIMEOUT_MS_CONFIG), time);
            this.client = new ConsumerNetworkClient(netClient, metadata, time, retryBackoffMs,
                    config.getInt(CommonClientConfigs.REQUEST_TIMEOUT_MS_CONFIG));
            this.coordinator = new WorkerCoordinator(this.client,
                    config.getString(DistributedConfig.GROUP_ID_CONFIG),
                    config.getInt(DistributedConfig.SESSION_TIMEOUT_MS_CONFIG),
                    config.getInt(DistributedConfig.HEARTBEAT_INTERVAL_MS_CONFIG),
                    metrics,
                    metricGrpPrefix,
                    this.time,
                    retryBackoffMs,
                    restUrl,
                    configStorage,
                    listener);

            AppInfoParser.registerAppInfo(JMX_PREFIX, clientId);
            log.debug("Connect group member created");
        } catch (Throwable t) {
            // call close methods if internal objects are already constructed
            // this is to prevent resource leak. see KAFKA-2121
            stop(true);
            // now propagate the exception
            throw new KafkaException("Failed to construct kafka consumer", t);
        }
    }

    public void stop() {
        if (stopped) return;
        stop(false);
    }

    public void ensureActive() {
        coordinator.ensureCoordinatorKnown();
        coordinator.ensureActiveGroup();
    }

    public void poll(long timeout) {
        if (timeout < 0)
            throw new IllegalArgumentException("Timeout must not be negative");

        // poll for new data until the timeout expires
        long remaining = timeout;
        while (remaining >= 0) {
            long start = time.milliseconds();
            coordinator.ensureCoordinatorKnown();
            coordinator.ensureActiveGroup();
            client.poll(remaining);
            remaining -= time.milliseconds() - start;
        }
    }

    /**
     * Interrupt any running poll() calls, causing a WakeupException to be thrown in the thread invoking that method.
     */
    public void wakeup() {
        this.client.wakeup();
    }

    /**
     * Get the member ID of this worker in the group of workers.
     *
     * This ID is the unique member ID automatically generated.
     *
     * @return the member ID
     */
    public String memberId() {
        return coordinator.memberId();
    }

    public void requestRejoin() {
        coordinator.requestRejoin();
    }

    public void maybeLeaveGroup() {
        coordinator.maybeLeaveGroup();
    }

    public String ownerUrl(String connector) {
        return coordinator.ownerUrl(connector);
    }

    public String ownerUrl(ConnectorTaskId task) {
        return coordinator.ownerUrl(task);
    }

    private void stop(boolean swallowException) {
        log.trace("Stopping the Connect group member.");
        AtomicReference<Throwable> firstException = new AtomicReference<Throwable>();
        this.stopped = true;
        ClientUtils.closeQuietly(coordinator, "coordinator", firstException);
        ClientUtils.closeQuietly(metrics, "consumer metrics", firstException);
        ClientUtils.closeQuietly(client, "consumer network client", firstException);
        AppInfoParser.unregisterAppInfo(JMX_PREFIX, clientId);
        if (firstException.get() != null && !swallowException)
            throw new KafkaException("Failed to stop the Connect group member", firstException.get());
        else
            log.debug("The Connect group member has stopped.");
    }
}