| /** |
| * |
| * 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.hadoop.fs; |
| |
| import java.io.*; |
| import java.nio.ByteBuffer; |
| import java.util.EnumSet; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.io.ByteBufferPool; |
| import org.apache.hadoop.fs.ByteBufferUtil; |
| import org.apache.hadoop.util.IdentityHashStore; |
| |
| /** Utility that wraps a {@link FSInputStream} in a {@link DataInputStream} |
| * and buffers input through a {@link BufferedInputStream}. */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class FSDataInputStream extends DataInputStream |
| implements Seekable, PositionedReadable, |
| ByteBufferReadable, HasFileDescriptor, CanSetDropBehind, CanSetReadahead, |
| HasEnhancedByteBufferAccess { |
| /** |
| * Map ByteBuffers that we have handed out to readers to ByteBufferPool |
| * objects |
| */ |
| private final IdentityHashStore<ByteBuffer, ByteBufferPool> |
| extendedReadBuffers |
| = new IdentityHashStore<ByteBuffer, ByteBufferPool>(0); |
| |
| public FSDataInputStream(InputStream in) { |
| super(in); |
| if( !(in instanceof Seekable) || !(in instanceof PositionedReadable) ) { |
| throw new IllegalArgumentException( |
| "In is not an instance of Seekable or PositionedReadable"); |
| } |
| } |
| |
| /** |
| * Seek to the given offset. |
| * |
| * @param desired offset to seek to |
| */ |
| @Override |
| public synchronized void seek(long desired) throws IOException { |
| ((Seekable)in).seek(desired); |
| } |
| |
| /** |
| * Get the current position in the input stream. |
| * |
| * @return current position in the input stream |
| */ |
| @Override |
| public long getPos() throws IOException { |
| return ((Seekable)in).getPos(); |
| } |
| |
| /** |
| * Read bytes from the given position in the stream to the given buffer. |
| * |
| * @param position position in the input stream to seek |
| * @param buffer buffer into which data is read |
| * @param offset offset into the buffer in which data is written |
| * @param length maximum number of bytes to read |
| * @return total number of bytes read into the buffer, or <code>-1</code> |
| * if there is no more data because the end of the stream has been |
| * reached |
| */ |
| @Override |
| public int read(long position, byte[] buffer, int offset, int length) |
| throws IOException { |
| return ((PositionedReadable)in).read(position, buffer, offset, length); |
| } |
| |
| /** |
| * Read bytes from the given position in the stream to the given buffer. |
| * Continues to read until <code>length</code> bytes have been read. |
| * |
| * @param position position in the input stream to seek |
| * @param buffer buffer into which data is read |
| * @param offset offset into the buffer in which data is written |
| * @param length the number of bytes to read |
| * @throws EOFException If the end of stream is reached while reading. |
| * If an exception is thrown an undetermined number |
| * of bytes in the buffer may have been written. |
| */ |
| @Override |
| public void readFully(long position, byte[] buffer, int offset, int length) |
| throws IOException { |
| ((PositionedReadable)in).readFully(position, buffer, offset, length); |
| } |
| |
| /** |
| * See {@link #readFully(long, byte[], int, int)}. |
| */ |
| @Override |
| public void readFully(long position, byte[] buffer) |
| throws IOException { |
| ((PositionedReadable)in).readFully(position, buffer, 0, buffer.length); |
| } |
| |
| /** |
| * Seek to the given position on an alternate copy of the data. |
| * |
| * @param targetPos position to seek to |
| * @return true if a new source is found, false otherwise |
| */ |
| @Override |
| public boolean seekToNewSource(long targetPos) throws IOException { |
| return ((Seekable)in).seekToNewSource(targetPos); |
| } |
| |
| /** |
| * Get a reference to the wrapped input stream. Used by unit tests. |
| * |
| * @return the underlying input stream |
| */ |
| @InterfaceAudience.LimitedPrivate({"HDFS"}) |
| public InputStream getWrappedStream() { |
| return in; |
| } |
| |
| @Override |
| public int read(ByteBuffer buf) throws IOException { |
| if (in instanceof ByteBufferReadable) { |
| return ((ByteBufferReadable)in).read(buf); |
| } |
| |
| throw new UnsupportedOperationException("Byte-buffer read unsupported by input stream"); |
| } |
| |
| @Override |
| public FileDescriptor getFileDescriptor() throws IOException { |
| if (in instanceof HasFileDescriptor) { |
| return ((HasFileDescriptor) in).getFileDescriptor(); |
| } else if (in instanceof FileInputStream) { |
| return ((FileInputStream) in).getFD(); |
| } else { |
| return null; |
| } |
| } |
| |
| @Override |
| public void setReadahead(Long readahead) |
| throws IOException, UnsupportedOperationException { |
| try { |
| ((CanSetReadahead)in).setReadahead(readahead); |
| } catch (ClassCastException e) { |
| throw new UnsupportedOperationException( |
| "this stream does not support setting the readahead " + |
| "caching strategy."); |
| } |
| } |
| |
| @Override |
| public void setDropBehind(Boolean dropBehind) |
| throws IOException, UnsupportedOperationException { |
| try { |
| ((CanSetDropBehind)in).setDropBehind(dropBehind); |
| } catch (ClassCastException e) { |
| throw new UnsupportedOperationException("this stream does not " + |
| "support setting the drop-behind caching setting."); |
| } |
| } |
| |
| @Override |
| public ByteBuffer read(ByteBufferPool bufferPool, int maxLength, |
| EnumSet<ReadOption> opts) |
| throws IOException, UnsupportedOperationException { |
| try { |
| return ((HasEnhancedByteBufferAccess)in).read(bufferPool, |
| maxLength, opts); |
| } |
| catch (ClassCastException e) { |
| ByteBuffer buffer = ByteBufferUtil. |
| fallbackRead(this, bufferPool, maxLength); |
| if (buffer != null) { |
| extendedReadBuffers.put(buffer, bufferPool); |
| } |
| return buffer; |
| } |
| } |
| |
| private static final EnumSet<ReadOption> EMPTY_READ_OPTIONS_SET = |
| EnumSet.noneOf(ReadOption.class); |
| |
| final public ByteBuffer read(ByteBufferPool bufferPool, int maxLength) |
| throws IOException, UnsupportedOperationException { |
| return read(bufferPool, maxLength, EMPTY_READ_OPTIONS_SET); |
| } |
| |
| @Override |
| public void releaseBuffer(ByteBuffer buffer) { |
| try { |
| ((HasEnhancedByteBufferAccess)in).releaseBuffer(buffer); |
| } |
| catch (ClassCastException e) { |
| ByteBufferPool bufferPool = extendedReadBuffers.remove( buffer); |
| if (bufferPool == null) { |
| throw new IllegalArgumentException("tried to release a buffer " + |
| "that was not created by this stream."); |
| } |
| bufferPool.putBuffer(buffer); |
| } |
| } |
| } |