| /* |
| * 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.cassandra.io.util; |
| |
| import java.io.Closeable; |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| import java.nio.channels.ReadableByteChannel; |
| import java.nio.channels.SeekableByteChannel; |
| |
| import com.google.common.base.Preconditions; |
| |
| /** |
| * Rough equivalent of BufferedInputStream and DataInputStream wrapping the input stream of a File or Socket |
| * Created to work around the fact that when BIS + DIS delegate to NIO for socket IO they will allocate large |
| * thread local direct byte buffers when a large array is used to read. |
| * |
| * There may also be some performance improvement due to using a DBB as the underlying buffer for IO and the removal |
| * of some indirection and delegation when it comes to reading out individual values, but that is not the goal. |
| * |
| * Closing NIODataInputStream will invoke close on the ReadableByteChannel provided at construction. |
| * |
| * NIODataInputStream is not thread safe. |
| */ |
| public class NIODataInputStream extends RebufferingInputStream |
| { |
| protected final ReadableByteChannel channel; |
| |
| private static ByteBuffer makeBuffer(int bufferSize) |
| { |
| ByteBuffer buffer = ByteBuffer.allocateDirect(bufferSize); |
| buffer.position(0); |
| buffer.limit(0); |
| |
| return buffer; |
| } |
| |
| public NIODataInputStream(ReadableByteChannel channel, ByteBuffer buffer) |
| { |
| super(buffer); |
| |
| Preconditions.checkNotNull(channel); |
| this.channel = channel; |
| } |
| |
| public NIODataInputStream(ReadableByteChannel channel, int bufferSize) |
| { |
| this(channel, makeBuffer(bufferSize)); |
| } |
| |
| @Override |
| protected void reBuffer() throws IOException |
| { |
| Preconditions.checkState(buffer.remaining() == 0); |
| buffer.clear(); |
| |
| while ((channel.read(buffer)) == 0) {} |
| |
| buffer.flip(); |
| } |
| |
| @Override |
| public void close() throws IOException |
| { |
| channel.close(); |
| super.close(); |
| } |
| |
| @Override |
| public int available() throws IOException |
| { |
| if (channel instanceof SeekableByteChannel) |
| { |
| SeekableByteChannel sbc = (SeekableByteChannel) channel; |
| long remainder = Math.max(0, sbc.size() - sbc.position()); |
| return (remainder > Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int)(remainder + buffer.remaining()); |
| } |
| return buffer.remaining(); |
| } |
| } |