org.apache.crunch.io.hbase.HFileReaderFactory.java Source code

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Here is the source code for org.apache.crunch.io.hbase.HFileReaderFactory.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.crunch.io.hbase;

import org.apache.crunch.io.FileReaderFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.io.hfile.CacheConfig;
import org.apache.hadoop.hbase.io.hfile.HFile;
import org.apache.hadoop.hbase.io.hfile.HFileScanner;

import java.io.IOException;
import java.util.Iterator;

public class HFileReaderFactory implements FileReaderFactory<KeyValue> {

    public static final String HFILE_SCANNER_CACHE_BLOCKS = "crunch.hfile.scanner.cache.blocks";
    public static final String HFILE_SCANNER_PREAD = "crunch.hfile.scanner.pread";

    @Override
    public Iterator<KeyValue> read(FileSystem fs, Path path) {
        Configuration conf = fs.getConf();
        CacheConfig cacheConfig = new CacheConfig(conf);
        try {
            HFile.Reader hfr = HFile.createReader(fs, path, cacheConfig);
            HFileScanner scanner = hfr.getScanner(conf.getBoolean(HFILE_SCANNER_CACHE_BLOCKS, false),
                    conf.getBoolean(HFILE_SCANNER_PREAD, false));
            scanner.seekTo();
            return new HFileIterator(scanner);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private static class HFileIterator implements Iterator<KeyValue> {

        private final HFileScanner scanner;
        private KeyValue curr;

        public HFileIterator(HFileScanner scanner) {
            this.scanner = scanner;
            this.curr = scanner.getKeyValue();
        }

        @Override
        public boolean hasNext() {
            return curr != null;
        }

        @Override
        public KeyValue next() {
            KeyValue ret = curr;
            try {
                if (scanner.next()) {
                    curr = scanner.getKeyValue();
                } else {
                    curr = null;
                }
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            return ret;
        }

        @Override
        public void remove() {
            throw new UnsupportedOperationException("HFileIterator is read-only");
        }
    }
}