org.apache.hadoop.hbase.regionserver.wal.BinaryCompatibleBaseDecoder.java Source code

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Here is the source code for org.apache.hadoop.hbase.regionserver.wal.BinaryCompatibleBaseDecoder.java

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/**
 * 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.hbase.regionserver.wal;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;

import javax.annotation.Nonnull;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.codec.Codec;

/**
 * This class is a copy paste version of org.apache.hadoop.hbase.codec.BaseDecoder class. 
 * This class is meant to be used in {@link IndexedWALEditCodec} when runtime version of
 * HBase is older than 1.1.3. This is needed to handle binary incompatibility introduced by
 * HBASE-14501. See PHOENIX-2629 and PHOENIX-2636 for details.
 */
public abstract class BinaryCompatibleBaseDecoder implements Codec.Decoder {
    protected static final Log LOG = LogFactory.getLog(BinaryCompatibleBaseDecoder.class);

    protected final InputStream in;
    private Cell current = null;

    protected static class PBIS extends PushbackInputStream {
        public PBIS(InputStream in, int size) {
            super(in, size);
        }

        public void resetBuf(int size) {
            this.buf = new byte[size];
            this.pos = size;
        }
    }

    public BinaryCompatibleBaseDecoder(final InputStream in) {
        this.in = new PBIS(in, 1);
    }

    @Override
    public boolean advance() throws IOException {
        int firstByte = in.read();
        if (firstByte == -1) {
            return false;
        } else {
            ((PBIS) in).unread(firstByte);
        }

        try {
            this.current = parseCell();
        } catch (IOException ioEx) {
            ((PBIS) in).resetBuf(1); // reset the buffer in case the underlying stream is read from upper layers
            rethrowEofException(ioEx);
        }
        return true;
    }

    private void rethrowEofException(IOException ioEx) throws IOException {
        boolean isEof = false;
        try {
            isEof = this.in.available() == 0;
        } catch (Throwable t) {
            LOG.trace("Error getting available for error message - ignoring", t);
        }
        if (!isEof)
            throw ioEx;
        if (LOG.isTraceEnabled()) {
            LOG.trace("Partial cell read caused by EOF", ioEx);
        }
        EOFException eofEx = new EOFException("Partial cell read");
        eofEx.initCause(ioEx);
        throw eofEx;
    }

    protected InputStream getInputStream() {
        return in;
    }

    /**
     * Extract a Cell.
     * @return a parsed Cell or throws an Exception. EOFException or a generic IOException maybe
     * thrown if EOF is reached prematurely. Does not return null.
     * @throws IOException
     */
    @Nonnull
    protected abstract Cell parseCell() throws IOException;

    @Override
    public Cell current() {
        return this.current;
    }
}