LocalBlockInStream.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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 tachyon.client;

import java.io.IOException;
import java.nio.ByteBuffer;

/**
 * BlockInStream for local block.
 */
public class LocalBlockInStream extends BlockInStream {
  private TachyonByteBuffer mTachyonBuffer = null;
  private ByteBuffer mBuffer = null;

  /**
   * @param file
   *          the file the block belongs to
   * @param readType
   *          the InStream's read type
   * @param blockIndex
   *          the index of the block in the file
   * @param buf
   *          the buffer of the whole block in local memory
   * @throws IOException
   */
  LocalBlockInStream(TachyonFile file, ReadType readType, int blockIndex, TachyonByteBuffer buf)
      throws IOException {
    super(file, readType, blockIndex);

    mTachyonBuffer = buf;
    mBuffer = mTachyonBuffer.DATA;
  }

  @Override
  public void close() throws IOException {
    if (!mClosed) {
      mTachyonBuffer.close();
    }
    mClosed = true;
  }

  @Override
  public int read() throws IOException {
    if (mBuffer.remaining() == 0) {
      close();
      return -1;
    }
    return mBuffer.get() & 0xFF;
  }

  @Override
  public int read(byte b[]) throws IOException {
    return read(b, 0, b.length);
  }

  @Override
  public int read(byte b[], int off, int len) throws IOException {
    if (b == null) {
      throw new NullPointerException();
    } else if (off < 0 || len < 0 || len > b.length - off) {
      throw new IndexOutOfBoundsException();
    } else if (len == 0) {
      return 0;
    }

    int ret = Math.min(len, mBuffer.remaining());
    if (ret == 0) {
      close();
      return -1;
    }
    mBuffer.get(b, off, ret);
    return ret;
  }

  @Override
  public void seek(long pos) throws IOException {
    if (pos < 0) {
      throw new IOException("pos is negative: " + pos);
    }
    mBuffer.position((int) pos);
  }

  @Override
  public long skip(long n) throws IOException {
    if (n <= 0) {
      return 0;
    }

    int ret = mBuffer.remaining();
    if (ret > n) {
      ret = (int) n;
    }
    mBuffer.position(mBuffer.position() + ret);
    return ret;
  }
}