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/***********************************************************************************************************************
 * 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.network.netty;

import eu.stratosphere.runtime.io.Buffer;
import eu.stratosphere.runtime.io.network.Envelope;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;

@ChannelHandler.Sharable
public class OutboundEnvelopeEncoder extends MessageToByteEncoder {

	public static final int HEADER_SIZE = 48;

	public static final int MAGIC_NUMBER = 0xBADC0FFE;

	@Override
	protected void encode(ChannelHandlerContext ctx, Envelope env, ByteBuf out) throws Exception {
		// --------------------------------------------------------------------
		// (1) header (48 bytes)
		// --------------------------------------------------------------------
		out.writeInt(MAGIC_NUMBER); // 4 bytes

		if (out.getInt(out.writerIndex()-4) != MAGIC_NUMBER) {
			throw new RuntimeException();
		}

		out.writeInt(env.getSequenceNumber()); // 4 bytes
		env.getJobID().writeTo(out); // 16 bytes
		env.getSource().writeTo(out); // 16 bytes
		out.writeInt(env.getEventsSerialized() != null ? env.getEventsSerialized().remaining() : 0); // 4 bytes
		out.writeInt(env.getBuffer() != null ? env.getBuffer().size() : 0); // 4 bytes
		// --------------------------------------------------------------------
		// (2) events (var length)
		// --------------------------------------------------------------------
		if (env.getEventsSerialized() != null) {
			out.writeBytes(env.getEventsSerialized());
		}

		// --------------------------------------------------------------------
		// (3) buffer (var length)
		// --------------------------------------------------------------------
		if (env.getBuffer() != null) {
			Buffer buffer = env.getBuffer();
			out.writeBytes(buffer.getMemorySegment().wrap(0, buffer.size()));

			// Recycle the buffer from OUR buffer pool after everything has been
			// copied to Nettys buffer space.
			buffer.recycleBuffer();
		}
	}
}