InStream.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.io.InputStream;

import tachyon.conf.UserConf;

/**
 * <code>InStream</code> is the base input stream class for TachyonFile streaming input methods.
 * It can only be gotten by calling the methods in <code>tachyon.client.TachyonFile</code>, but
 * can not be initialized by the client code.
 */
public abstract class InStream extends InputStream {
  protected final UserConf USER_CONF = UserConf.get();
  protected final TachyonFile FILE;
  protected final TachyonFS TFS;
  protected final ReadType READ_TYPE;

  /**
   * @param file
   *          the input file of the InStream
   * @param readType
   *          the InStream's read type
   */
  InStream(TachyonFile file, ReadType readType) {
    FILE = file;
    TFS = FILE.TFS;
    READ_TYPE = readType;
  }

  @Override
  public abstract void close() throws IOException;

  @Override
  public abstract int read() throws IOException;

  @Override
  public abstract int read(byte b[]) throws IOException;

  @Override
  public abstract int read(byte b[], int off, int len) throws IOException;

  /**
   * Sets the stream pointer offset, measured from the beginning of this stream, at which the next
   * read or write occurs. The offset may be set beyond the end of the stream.
   * 
   * @param pos
   *          the offset position, measured in bytes from the beginning of the InStream, at which
   *          to set the stream pointer.
   * @throws IOException
   *           if pos is less than 0 or if an I/O error occurs.
   */
  public abstract void seek(long pos) throws IOException;

  @Override
  public abstract long skip(long n) throws IOException;
}