| /* |
| * 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.flink.core.fs; |
| |
| import org.apache.flink.annotation.Internal; |
| import org.apache.flink.util.IOUtils; |
| import org.apache.flink.util.Preconditions; |
| |
| import java.io.EOFException; |
| import java.io.IOException; |
| |
| /** |
| * Abstract base class for wrappers over multiple {@link FSDataInputStream}, which gives a contiguous view on all inner |
| * streams and makes them look like a single stream, in which we can read, seek, etc. |
| */ |
| @Internal |
| public abstract class AbstractMultiFSDataInputStream extends FSDataInputStream { |
| |
| /** Inner stream for the currently accessed segment of the virtual global stream. */ |
| protected FSDataInputStream delegate; |
| |
| /** Position in the virtual global stream. */ |
| protected long totalPos; |
| |
| /** Total available bytes in the virtual global stream. */ |
| protected long totalAvailable; |
| |
| public AbstractMultiFSDataInputStream() { |
| this.totalPos = 0L; |
| } |
| |
| @Override |
| public void seek(long desired) throws IOException { |
| |
| if (desired == totalPos) { |
| return; |
| } |
| |
| Preconditions.checkArgument(desired >= 0L); |
| |
| if (desired > totalAvailable) { |
| throw new EOFException(); |
| } |
| |
| IOUtils.closeQuietly(delegate); |
| delegate = getSeekedStreamForOffset(desired); |
| |
| this.totalPos = desired; |
| } |
| |
| @Override |
| public long getPos() throws IOException { |
| return totalPos; |
| } |
| |
| @Override |
| public int read() throws IOException { |
| |
| if (null == delegate) { |
| return -1; |
| } |
| |
| int val = delegate.read(); |
| |
| if (-1 == val) { |
| IOUtils.closeQuietly(delegate); |
| if (totalPos < totalAvailable) { |
| delegate = getSeekedStreamForOffset(totalPos); |
| } else { |
| delegate = null; |
| } |
| return read(); |
| } |
| |
| ++totalPos; |
| return val; |
| } |
| |
| @Override |
| public void close() throws IOException { |
| IOUtils.closeQuietly(delegate); |
| } |
| |
| @Override |
| public long skip(long n) throws IOException { |
| seek(totalPos + n); |
| return n; |
| } |
| |
| /** |
| * Delivers a the right stream for the given global stream offset. The returned stream is already seeked to the |
| * right local offset that correctly reflects the global offset. |
| * |
| * @param globalStreamOffset the global offset to which we seek |
| * @return a sub-stream, seeked to the correct local offset w.r.t. the global offset. |
| * @throws IOException |
| */ |
| protected abstract FSDataInputStream getSeekedStreamForOffset(long globalStreamOffset) throws IOException; |
| } |