exec/java-exec/src/main/java/org/apache/drill/exec/store/ResourceInputStream.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 org.apache.drill.exec.store;

import java.io.ByteArrayInputStream;
import java.io.EOFException;
import java.io.IOException;

import org.apache.hadoop.fs.PositionedReadable;
import org.apache.hadoop.fs.Seekable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.Preconditions;

public class ResourceInputStream extends ByteArrayInputStream implements Seekable, PositionedReadable {
  static final Logger logger = LoggerFactory.getLogger(ResourceInputStream.class);

  public ResourceInputStream(byte[] bytes) {
    super(bytes);
  }

  @Override
  public void readFully(long position, byte[] buffer) throws IOException {
    int l = read(position, buffer, 0, buffer.length);
    if (l < buffer.length) {
      throw new EOFException();
    }
  }

  @Override
  public int read(long position, byte b[], int off, int len) {
    Preconditions.checkNotNull(b);
    Preconditions.checkPositionIndexes(off, off + len, b.length);

    int start = (int) position;

    if (start >= count) {
        return -1;
    }

    int avail = count - start;
    if (len > avail) {
        len = avail;
    }
    if (len <= 0) {
        return 0;
    }
    System.arraycopy(buf, start, b, off, len);
    return len;
  }

  @Override
  public void readFully(long position, byte[] buffer, int offset, int length) throws IOException {
    int l = read(position, buffer, offset, length);
    if (l < length) {
      throw new EOFException();
    }
  }

  @Override
  public long getPos() throws IOException {
    return pos;
  }

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

  @Override
  public boolean seekToNewSource(long arg0) throws IOException {
    seek(arg0);
    return true;
  }

  @Override
  public void seek(long arg0) throws IOException {
    if (buf.length > arg0) {
      pos = (int) arg0;
    } else {
      throw new EOFException();
    }
  }
}