org.apache.accumulo.tserver.log.RecoveryLogsIterator.java Source code

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Here is the source code for org.apache.accumulo.tserver.log.RecoveryLogsIterator.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.accumulo.tserver.log;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map.Entry;

import org.apache.accumulo.server.fs.VolumeManager;
import org.apache.accumulo.tserver.logger.LogFileKey;
import org.apache.accumulo.tserver.logger.LogFileValue;
import org.apache.hadoop.fs.Path;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Iterators;
import com.google.common.collect.UnmodifiableIterator;

/**
 * Iterates over multiple sorted recovery logs merging them into a single sorted stream.
 */
public class RecoveryLogsIterator implements CloseableIterator<Entry<LogFileKey, LogFileValue>> {

    private static final Logger LOG = LoggerFactory.getLogger(RecoveryLogsIterator.class);

    List<CloseableIterator<Entry<LogFileKey, LogFileValue>>> iterators;
    private UnmodifiableIterator<Entry<LogFileKey, LogFileValue>> iter;

    /**
     * Iterates only over keys in the range [start,end].
     */
    RecoveryLogsIterator(VolumeManager fs, List<Path> recoveryLogPaths, LogFileKey start, LogFileKey end)
            throws IOException {

        iterators = new ArrayList<>(recoveryLogPaths.size());

        try {
            for (Path log : recoveryLogPaths) {
                LOG.debug("Opening recovery log {}", log.getName());
                RecoveryLogReader rlr = new RecoveryLogReader(fs, log, start, end);
                if (rlr.hasNext()) {
                    LOG.debug("Write ahead log {} has data in range {} {}", log.getName(), start, end);
                    iterators.add(rlr);
                } else {
                    LOG.debug("Write ahead log {} has no data in range {} {}", log.getName(), start, end);
                    rlr.close();
                }
            }

            iter = Iterators.mergeSorted(iterators, (o1, o2) -> o1.getKey().compareTo(o2.getKey()));

        } catch (RuntimeException | IOException e) {
            try {
                close();
            } catch (Exception e2) {
                e.addSuppressed(e2);
            }
            throw e;
        }
    }

    @Override
    public boolean hasNext() {
        return iter.hasNext();
    }

    @Override
    public Entry<LogFileKey, LogFileValue> next() {
        return iter.next();
    }

    @Override
    public void remove() {
        throw new UnsupportedOperationException("remove");
    }

    @Override
    public void close() {
        for (CloseableIterator<?> reader : iterators) {
            try {
                reader.close();
            } catch (IOException e) {
                LOG.debug("Failed to close reader", e);
            }
        }
    }
}