org.apache.hadoop.hbase.codec.BaseDecoder.java Source code

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Here is the source code for org.apache.hadoop.hbase.codec.BaseDecoder.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.codec;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hbase.Cell;

/**
 * TODO javadoc
 */
@InterfaceAudience.Private
public abstract class BaseDecoder implements Codec.Decoder {
    protected static final Log LOG = LogFactory.getLog(BaseDecoder.class);
    protected final InputStream in;
    private boolean hasNext = true;
    private Cell current = null;

    public BaseDecoder(final InputStream in) {
        this.in = in;
    }

    @Override
    public boolean advance() throws IOException {
        if (!this.hasNext)
            return this.hasNext;
        if (this.in.available() == 0) {
            this.hasNext = false;
            return this.hasNext;
        }
        try {
            this.current = parseCell();
        } catch (IOException ioEx) {
            rethrowEofException(ioEx);
        }
        return this.hasNext;
    }

    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;
        LOG.error("Partial cell read caused by EOF: " + ioEx);
        EOFException eofEx = new EOFException("Partial cell read");
        eofEx.initCause(ioEx);
        throw eofEx;
    }

    /**
     * @return extract a Cell
     * @throws IOException
     */
    protected abstract Cell parseCell() throws IOException;

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