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The Netty project is an effort to provide an asynchronous event-driven network application framework and tools for rapid development of maintainable high performance and high scalability protocol servers and clients. In other words, Netty is a NIO client server framework which enables quick and easy development of network applications such as protocol servers and clients. It greatly simplifies and streamlines network programming such as TCP and UDP socket server.

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/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you 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.jboss.netty.handler.stream;

import static org.jboss.netty.buffer.ChannelBuffers.*;

import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;

import org.jboss.netty.buffer.ChannelBuffer;

/**
 * A {@link ChunkedInput} that fetches data from a {@link ReadableByteChannel}
 * chunk by chunk.  Please note that the {@link ReadableByteChannel} must
 * operate in blocking mode.  Non-blocking mode channels are not supported.
 */
public class ChunkedNioStream implements ChunkedInput {

    private final ReadableByteChannel in;

    private final int chunkSize;
    private long offset;

    /**
     * Associated ByteBuffer
     */
    private final ByteBuffer byteBuffer;

    /**
     * Creates a new instance that fetches data from the specified channel.
     */
    public ChunkedNioStream(ReadableByteChannel in) {
        this(in, ChunkedStream.DEFAULT_CHUNK_SIZE);
    }

    /**
     * Creates a new instance that fetches data from the specified channel.
     *
     * @param chunkSize the number of bytes to fetch on each
     *                  {@link #nextChunk()} call
     */
    public ChunkedNioStream(ReadableByteChannel in, int chunkSize) {
        if (in == null) {
            throw new NullPointerException("in");
        }
        if (chunkSize <= 0) {
            throw new IllegalArgumentException("chunkSize: " + chunkSize +
                    " (expected: a positive integer)");
        }
        this.in = in;
        offset = 0;
        this.chunkSize = chunkSize;
        byteBuffer = ByteBuffer.allocate(chunkSize);
    }

    /**
     * Returns the number of transferred bytes.
     */
    public long getTransferredBytes() {
        return offset;
    }

    public boolean hasNextChunk() throws Exception {
        if (byteBuffer.position() > 0) {
            // A previous read was not over, so there is a next chunk in the buffer at least
            return true;
        }
        if (in.isOpen()) {
            // Try to read a new part, and keep this part (no rewind)
            int b = in.read(byteBuffer);
            if (b < 0) {
                return false;
            } else {
                offset += b;
                return true;
            }
        }
        return false;
    }

    public boolean isEndOfInput() throws Exception {
        return !hasNextChunk();
    }

    public void close() throws Exception {
        in.close();
    }

    public Object nextChunk() throws Exception {
        if (!hasNextChunk()) {
            return null;
        }
        // buffer cannot be not be empty from there
        int readBytes = byteBuffer.position();
        for (;;) {
            int localReadBytes = in.read(byteBuffer);
            if (localReadBytes < 0) {
                break;
            }
            readBytes += localReadBytes;
            offset += localReadBytes;

            if (readBytes == chunkSize) {
                break;
            }
        }
        byteBuffer.flip();
        // copy since buffer is keeped for next usage
        ChannelBuffer buffer = copiedBuffer(byteBuffer);
        byteBuffer.clear();
        return buffer;
    }
}