com.microsoft.reef.io.network.impl.NSConnection Maven / Gradle / Ivy

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/**
 * Copyright (C) 2013 Microsoft Corporation
 *
 * 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.microsoft.reef.io.network.impl;

import com.microsoft.reef.exception.evaluator.NetworkException;
import com.microsoft.reef.io.network.Connection;
import com.microsoft.reef.io.network.naming.exception.NamingException;
import com.microsoft.wake.Identifier;
import com.microsoft.wake.remote.Codec;
import com.microsoft.wake.remote.transport.Link;
import com.microsoft.wake.remote.transport.LinkListener;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * A connection from the network service
 */
class NSConnection implements Connection {
  private static final Logger LOG = Logger.getLogger(NSConnection.class.getName());
  private final Identifier srcId;
  private final Identifier destId;
  private final LinkListener> listener;
  private final NetworkService service;
  private final Codec> codec;

  // link can change when an endpoint physical address changes
  private Link> link;

  /**
   * Constructs a connection
   *
   * @param srcId    a source identifier
   * @param destId   a destination identifier
   * @param listener a link listener
   * @param service  a network service
   */
  NSConnection(final Identifier srcId, final Identifier destId, final LinkListener listener,
               final NetworkService service) {
    this.srcId = srcId;
    this.destId = destId;
    this.listener = new NSMessageLinkListener(listener);
    this.service = service;
    this.codec = new NSMessageCodec(service.getCodec(), service.getIdentifierFactory());
  }

  /**
   * Opens the connection
   *
   * @throws a network exception
   */
  @Override
  public void open() throws NetworkException {
    try {
      LOG.log(Level.FINE, "looking up {0}", destId);
      // naming lookup
      final InetSocketAddress addr = service.getNameClient().lookup(destId);
      if (addr == null)
        throw new NamingException("Cannot resolve " + destId);
      LOG.log(Level.FINE, "Resolved {0} to {1}", new Object[]{destId, addr});
      // connect to a remote address
      link = service.getTransport().open(addr, codec, listener);
      LOG.log(Level.FINE, "Transport returned a link {0}", link);
    } catch (Exception e) {
      throw new NetworkException(e.getCause());
    }
  }

  /**
   * Writes an object to the connection
   *
   * @param obj an object of type T
   * @throws a network exception
   */
  @Override
  public void write(T obj) throws NetworkException {
    try {
      link.write(new NSMessage(srcId, destId, obj));
    } catch (final IOException e) {
      throw new NetworkException(e);
    }
  }

  /**
   * Closes the connection and unregisters it from the service
   */
  @Override
  public void close() throws NetworkException {
    service.remove(destId);
  }

}

/**
 * No-op link listener
 *
 * @param 
 */
class NSMessageLinkListener implements LinkListener> {

  NSMessageLinkListener(LinkListener listener) {
  }

  @Override
  public void messageReceived(NSMessage message) {
  }

}