TopicRegistrationInfo.java

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/*
 * Copyright (C) 2012 Google 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 org.ros.internal.node.server.master;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;

import org.ros.master.client.TopicSystemState;
import org.ros.namespace.GraphName;
import org.ros.node.topic.Subscriber;

import java.util.Set;

public class TopicRegistrationInfo {

  private final GraphName topicName;

  private String messageType;

  private boolean isPublisherDefinedMessageType;

  private final Set<NodeRegistrationInfo> publishers;

  private final Set<NodeRegistrationInfo> subscribers;

  public TopicRegistrationInfo(GraphName topicName) {
    this.topicName = topicName;
    publishers = Sets.newHashSet();
    subscribers = Sets.newHashSet();
    isPublisherDefinedMessageType = false;
  }

  public GraphName getTopicName() {
    return topicName;
  }

  public String getMessageType() {
    return messageType;
  }

  public boolean hasPublishers() {
    return !publishers.isEmpty();
  }

  public boolean hasSubscribers() {
    return !subscribers.isEmpty();
  }

  public boolean hasRegistrations() {
    return hasPublishers() || hasSubscribers();
  }

  public Set<NodeRegistrationInfo> getPublishers() {
    return ImmutableSet.copyOf(publishers);
  }

  public void addPublisher(NodeRegistrationInfo publisher, String messageType) {
    Preconditions.checkNotNull(publisher);

    publishers.add(publisher);
    setMessageType(messageType, true);
  }

  public boolean removePublisher(NodeRegistrationInfo publisher) {
    return publishers.remove(publisher);
  }

  public Set<NodeRegistrationInfo> getSubscribers() {
    return ImmutableSet.copyOf(subscribers);
  }

  public void addSubscriber(NodeRegistrationInfo subscriber, String messageType) {
    Preconditions.checkNotNull(subscriber);
    subscribers.add(subscriber);

    setMessageType(messageType, false);
  }

  public boolean removeSubscriber(NodeRegistrationInfo subscriber) {
    return subscribers.remove(subscriber);
  }

  private void setMessageType(String topicMessageType, boolean isPublisher) {
    // The most recent association of topic name to message type wins.
    // However, subscription associations are always trumped by publisher
    // associations.
    if (isPublisher) {
      // Publishers always trump.
      messageType = topicMessageType;
      isPublisherDefinedMessageType = true;
    } else {
      // Is a subscriber.
      if (!Subscriber.TOPIC_MESSAGE_TYPE_WILDCARD.equals(topicMessageType)) {
        if (messageType != null) {
          // if has only been subscribers giving the type, register it.
          if (!isPublisherDefinedMessageType) {
            messageType = topicMessageType;
          }
        } else {
          // Not registered yet, so no worry about trumping.
          messageType = topicMessageType;
        }
      }
    }
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + topicName.hashCode();
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj)
      return true;
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    TopicRegistrationInfo other = (TopicRegistrationInfo) obj;
    if (!topicName.equals(other.topicName))
      return false;
    return true;
  }
}