/***********************************************************************************************************************
 * Copyright (C) 2010-2014 by the Stratosphere project (http://stratosphere.eu)
 *
 * 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 eu.stratosphere.runtime.io.channels;

import java.io.IOException;

import eu.stratosphere.nephele.event.task.AbstractEvent;
import eu.stratosphere.nephele.jobgraph.JobID;
import eu.stratosphere.runtime.io.network.Envelope;
import eu.stratosphere.runtime.io.network.EnvelopeDispatcher;

/**
 * The base class for channel objects.
 * <p>
 * Every channel has an index (at the corresponding gate), ID, and type. The connected channel is given by the ID of
 * destination channel.
 */
public abstract class Channel {

	private final ChannelID id;

	private final ChannelID connectedId;

	private final int index;

	private final ChannelType type;

	protected EnvelopeDispatcher envelopeDispatcher;

	/**
	 * Auxiliary constructor for channels
	 * 
	 * @param index the index of the channel in either the output or input gate
	 * @param id the ID of the channel
	 * @param connectedId the ID of the channel this channel is connected to
	 */
	protected Channel(int index, ChannelID id, ChannelID connectedId, ChannelType type) {
		this.index = index;
		this.id = id;
		this.connectedId = connectedId;
		this.type = type;
	}

	public int getIndex() {
		return this.index;
	}

	public ChannelID getID() {
		return this.id;
	}

	public ChannelID getConnectedId() {
		return this.connectedId;
	}

	public ChannelType getChannelType() {
		return this.type;
	}

	/**
	 * Registers an EnvelopeDispatcher with this channel at runtime.
	 *
	 * @param envelopeDispatcher the envelope dispatcher to use for data transfers
	 */
	public void registerEnvelopeDispatcher(EnvelopeDispatcher envelopeDispatcher) {
		this.envelopeDispatcher = envelopeDispatcher;
	}

	// -----------------------------------------------------------------------------------------------------------------

	public abstract JobID getJobID();

	public abstract boolean isInputChannel();

	public abstract boolean isClosed() throws IOException, InterruptedException;

	public abstract void transferEvent(AbstractEvent event) throws IOException, InterruptedException;

	public abstract void queueEnvelope(Envelope envelope);

	// nothing to do for buffer oriented runtime => TODO remove with pending changes for input side
	public abstract void releaseAllResources();

	// nothing to do for buffer oriented runtime => TODO remove with pending changes for input side
	public abstract void destroy();
}