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/*
 * 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.clients.consumer.internals;

import org.apache.kafka.clients.ApiVersions;
import org.apache.kafka.clients.ClientUtils;
import org.apache.kafka.clients.GroupRebalanceConfig;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.internals.events.ApplicationEvent;
import org.apache.kafka.clients.consumer.internals.events.BackgroundEvent;
import org.apache.kafka.clients.consumer.internals.events.EventHandler;
import org.apache.kafka.common.internals.ClusterResourceListeners;
import org.apache.kafka.common.metrics.Metrics;
import org.apache.kafka.common.metrics.Sensor;
import org.apache.kafka.common.utils.LogContext;
import org.apache.kafka.common.utils.Time;

import java.net.InetSocketAddress;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

/**
 * An {@code EventHandler} that uses a single background thread to consume {@code ApplicationEvent} and produce
 * {@code BackgroundEvent} from the {@ConsumerBackgroundThread}.
 */
public class DefaultEventHandler implements EventHandler {
    private final BlockingQueue applicationEventQueue;
    private final BlockingQueue backgroundEventQueue;
    private final DefaultBackgroundThread backgroundThread;

    public DefaultEventHandler(final ConsumerConfig config,
                               final GroupRebalanceConfig groupRebalanceConfig,
                               final LogContext logContext,
                               final SubscriptionState subscriptionState,
                               final ApiVersions apiVersions,
                               final Metrics metrics,
                               final ClusterResourceListeners clusterResourceListeners,
                               final Sensor fetcherThrottleTimeSensor) {
        this(Time.SYSTEM,
                config,
                groupRebalanceConfig,
                logContext,
                new LinkedBlockingQueue<>(),
                new LinkedBlockingQueue<>(),
                subscriptionState,
                apiVersions,
                metrics,
                clusterResourceListeners,
                fetcherThrottleTimeSensor);
    }

    public DefaultEventHandler(final Time time,
                               final ConsumerConfig config,
                               final GroupRebalanceConfig groupRebalanceConfig,
                               final LogContext logContext,
                               final BlockingQueue applicationEventQueue,
                               final BlockingQueue backgroundEventQueue,
                               final SubscriptionState subscriptionState,
                               final ApiVersions apiVersions,
                               final Metrics metrics,
                               final ClusterResourceListeners clusterResourceListeners,
                               final Sensor fetcherThrottleTimeSensor) {
        this.applicationEventQueue = applicationEventQueue;
        this.backgroundEventQueue = backgroundEventQueue;

        // Bootstrap a metadata object with the bootstrap server IP address, which will be used once for the
        // subsequent metadata refresh once the background thread has started up.
        final ConsumerMetadata metadata = new ConsumerMetadata(config,
                subscriptionState,
                logContext,
                clusterResourceListeners);
        final List addresses = ClientUtils.parseAndValidateAddresses(config);
        metadata.bootstrap(addresses);

        this.backgroundThread = new DefaultBackgroundThread(
            time,
            config,
            groupRebalanceConfig,
            logContext,
            this.applicationEventQueue,
            this.backgroundEventQueue,
            metadata,
            subscriptionState,
            apiVersions,
            metrics,
            fetcherThrottleTimeSensor);
        backgroundThread.start();
    }

    // VisibleForTesting
    DefaultEventHandler(final DefaultBackgroundThread backgroundThread,
                        final BlockingQueue applicationEventQueue,
                        final BlockingQueue backgroundEventQueue) {
        this.backgroundThread = backgroundThread;
        this.applicationEventQueue = applicationEventQueue;
        this.backgroundEventQueue = backgroundEventQueue;
        backgroundThread.start();
    }

    @Override
    public Optional poll() {
        return Optional.ofNullable(backgroundEventQueue.poll());
    }

    @Override
    public boolean isEmpty() {
        return backgroundEventQueue.isEmpty();
    }

    @Override
    public boolean add(final ApplicationEvent event) {
        backgroundThread.wakeup();
        return applicationEventQueue.add(event);
    }

    public void close() {
        try {
            backgroundThread.close();
        } catch (final Exception e) {
            throw new RuntimeException(e);
        }
    }
}