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The official Couchbase JVM Core IO Library
There is a newer version: 2.7.0
/*
 * Copyright (c) 2018 Couchbase, Inc.
 *
 * 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 com.couchbase.client.core.cnc;

import com.couchbase.client.core.annotation.Stability;
import reactor.core.publisher.Mono;

import java.time.Duration;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.function.Consumer;

/**
 * This super simple event bus should be used in testing only to assert certain
 * events got pushed through.
 */
@Stability.Internal
public class SimpleEventBus implements EventBus {

  /**
   * Holds all published events until cleared.
   */
  private List publishedEvents = new ArrayList<>();

  /**
   * If system event should be ignored, since they add noise and nondeterminism
   * to the event bus in assertions.
   */
  private final boolean ignoreSystemEvents;

  /**
   * Holds a (potential empty) list of
   */
  private final List> eventsToIgnore;

  /**
   * Creates a new {@link SimpleEventBus}.
   *
   * Note that in general you want to ignore system events since they add nondeterminism during
   * assertions when things like garbage collections happen. Of course if you need to test/verify
   * system events, set the argument to false.
   *
   * @param ignoreSystemEvents true if they should be ignored (recommended), false otherwise.
   */
  public SimpleEventBus(final boolean ignoreSystemEvents) {
    this(ignoreSystemEvents, Collections.emptyList());
  }

  /**
   * Creates a new {@link SimpleEventBus}.
   *
   * Note that in general you want to ignore system events since they add nondeterminism during
   * assertions when things like garbage collections happen. Of course if you need to test/verify
   * system events, set the argument to false.
   *
   * @param ignoreSystemEvents true if they should be ignored (recommended), false otherwise.
   * @param othersToIgnore other list of events to ignore.
   */
  public SimpleEventBus(final boolean ignoreSystemEvents, List> othersToIgnore) {
    this.ignoreSystemEvents = ignoreSystemEvents;
    this.eventsToIgnore = Collections.synchronizedList(othersToIgnore);
  }

  @Override
  public synchronized PublishResult publish(final Event event) {
    boolean inListToIgnore = eventsToIgnore.contains(event.getClass());
    if (!inListToIgnore && (!ignoreSystemEvents || !event.category().equals(Event.Category.SYSTEM.path()))) {
      publishedEvents.add(event);
    }
    return PublishResult.SUCCESS;
  }

  @Override
  public synchronized EventSubscription subscribe(final Consumer consumer) {
    return null;
  }

  @Override
  public synchronized void unsubscribe(final EventSubscription subscription) {

  }

  public synchronized List publishedEvents() {
    return new ArrayList<>(publishedEvents);
  }

  public synchronized void clear() {
    publishedEvents.clear();
  }

  @Override
  public Mono start() {
    return Mono.empty();
  }

  @Override
  public Mono stop(final Duration timeout) {
    return Mono.empty();
  }

}