001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.hbase.codec; 019 020import edu.umd.cs.findbugs.annotations.NonNull; 021import java.io.EOFException; 022import java.io.IOException; 023import java.io.InputStream; 024import java.io.PushbackInputStream; 025import org.apache.hadoop.hbase.ExtendedCell; 026import org.apache.hadoop.hbase.HBaseInterfaceAudience; 027import org.apache.yetus.audience.InterfaceAudience; 028import org.slf4j.Logger; 029import org.slf4j.LoggerFactory; 030 031/** 032 * Base implementation for {@link Codec.Decoder}. 033 */ 034@InterfaceAudience.LimitedPrivate({ HBaseInterfaceAudience.COPROC, HBaseInterfaceAudience.PHOENIX }) 035public abstract class BaseDecoder implements Codec.Decoder { 036 protected static final Logger LOG = LoggerFactory.getLogger(BaseDecoder.class); 037 038 protected final InputStream in; 039 private ExtendedCell current = null; 040 041 protected static class PBIS extends PushbackInputStream { 042 public PBIS(InputStream in, int size) { 043 super(in, size); 044 } 045 046 public void resetBuf(int size) { 047 this.buf = new byte[size]; 048 this.pos = size; 049 } 050 } 051 052 public BaseDecoder(final InputStream in) { 053 this.in = new PBIS(in, 1); 054 } 055 056 @Override 057 public boolean advance() throws IOException { 058 int firstByte = in.read(); 059 if (firstByte == -1) { 060 return false; 061 } else { 062 ((PBIS) in).unread(firstByte); 063 } 064 065 try { 066 this.current = parseCell(); 067 } catch (IOException ioEx) { 068 ((PBIS) in).resetBuf(1); // reset the buffer in case the underlying stream is read from upper 069 // layers 070 rethrowEofException(ioEx); 071 } 072 return true; 073 } 074 075 private void rethrowEofException(IOException ioEx) throws IOException { 076 boolean isEof = false; 077 try { 078 isEof = this.in.available() == 0; 079 } catch (Throwable t) { 080 LOG.trace("Error getting available for error message - ignoring", t); 081 } 082 if (!isEof) throw ioEx; 083 if (LOG.isTraceEnabled()) { 084 LOG.trace("Partial cell read caused by EOF", ioEx); 085 } 086 EOFException eofEx = new EOFException("Partial cell read"); 087 eofEx.initCause(ioEx); 088 throw eofEx; 089 } 090 091 protected InputStream getInputStream() { 092 return in; 093 } 094 095 /** 096 * Extract a Cell. 097 * @return a parsed Cell or throws an Exception. EOFException or a generic IOException maybe 098 * thrown if EOF is reached prematurely. Does not return null. 099 */ 100 @NonNull 101 protected abstract ExtendedCell parseCell() throws IOException; 102 103 @Override 104 public ExtendedCell current() { 105 return this.current; 106 } 107}