co.cask.cdap.data2.transaction.stream.leveldb.LevelDBStreamFileConsumer.java Source code

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Here is the source code for co.cask.cdap.data2.transaction.stream.leveldb.LevelDBStreamFileConsumer.java

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/*
 * Copyright  2014 Cask Data, Inc.
 *
 * Licensed 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 co.cask.cdap.data2.transaction.stream.leveldb;

import co.cask.cdap.api.common.Bytes;
import co.cask.cdap.api.dataset.table.Row;
import co.cask.cdap.api.dataset.table.Scanner;
import co.cask.cdap.common.conf.CConfiguration;
import co.cask.cdap.data.file.FileReader;
import co.cask.cdap.data.file.ReadFilter;
import co.cask.cdap.data.stream.StreamEventOffset;
import co.cask.cdap.data.stream.StreamFileOffset;
import co.cask.cdap.data2.dataset2.lib.table.leveldb.KeyValue;
import co.cask.cdap.data2.dataset2.lib.table.leveldb.LevelDBTableCore;
import co.cask.cdap.data2.queue.ConsumerConfig;
import co.cask.cdap.data2.transaction.stream.AbstractStreamFileConsumer;
import co.cask.cdap.data2.transaction.stream.StreamConfig;
import co.cask.cdap.data2.transaction.stream.StreamConsumerState;
import co.cask.cdap.data2.transaction.stream.StreamConsumerStateStore;
import co.cask.tephra.Transaction;
import com.google.common.collect.Maps;

import java.io.IOException;
import java.util.Arrays;
import java.util.Map;
import java.util.NavigableMap;
import javax.annotation.Nullable;

/**
 *
 */
public final class LevelDBStreamFileConsumer extends AbstractStreamFileConsumer {

    // used for undoing state. The value does not matter, but the OcTable interface was written to expect some value.
    private static final byte[] DUMMY_STATE_CONTENT = {};

    private final LevelDBTableCore tableCore;
    private final Object dbLock;
    private final NavigableMap<byte[], NavigableMap<byte[], byte[]>> rowMapForClaim;
    private final NavigableMap<byte[], byte[]> colMapForClaim;

    /**
     * @param streamConfig   Stream configuration.
     * @param consumerConfig Consumer configuration.
     * @param reader         For reading stream events. This class is responsible for closing the reader.
     */
    public LevelDBStreamFileConsumer(CConfiguration cConf, StreamConfig streamConfig, ConsumerConfig consumerConfig,
            FileReader<StreamEventOffset, Iterable<StreamFileOffset>> reader, StreamConsumerStateStore stateStore,
            StreamConsumerState beginConsumerState, @Nullable ReadFilter extraFilter, LevelDBTableCore tableCore,
            Object dbLock) {
        super(cConf, streamConfig, consumerConfig, reader, stateStore, beginConsumerState, extraFilter);
        this.tableCore = tableCore;
        this.dbLock = dbLock;
        this.rowMapForClaim = Maps.newTreeMap(Bytes.BYTES_COMPARATOR);
        this.colMapForClaim = Maps.newTreeMap(Bytes.BYTES_COMPARATOR);
    }

    @Override
    protected boolean claimFifoEntry(byte[] row, byte[] value, byte[] oldValue) throws IOException {
        synchronized (dbLock) {
            Map<byte[], byte[]> values = tableCore.getRow(row, new byte[][] { stateColumnName }, null, null, -1,
                    Transaction.ALL_VISIBLE_LATEST);
            if (!Arrays.equals(values.get(stateColumnName), oldValue)) {
                return false;
            }

            rowMapForClaim.clear();
            colMapForClaim.clear();
            colMapForClaim.put(stateColumnName, value);
            rowMapForClaim.put(row, colMapForClaim);

            tableCore.persist(rowMapForClaim, KeyValue.LATEST_TIMESTAMP);
            return true;
        }
    }

    @Override
    protected void updateState(Iterable<byte[]> rows, int size, byte[] value) throws IOException {
        NavigableMap<byte[], NavigableMap<byte[], byte[]>> changes = Maps.newTreeMap(Bytes.BYTES_COMPARATOR);
        for (byte[] row : rows) {
            NavigableMap<byte[], byte[]> values = Maps.newTreeMap(Bytes.BYTES_COMPARATOR);
            values.put(stateColumnName, value);
            changes.put(row, values);
        }
        tableCore.persist(changes, KeyValue.LATEST_TIMESTAMP);
    }

    @Override
    protected void undoState(Iterable<byte[]> rows, int size) throws IOException {
        NavigableMap<byte[], NavigableMap<byte[], byte[]>> changes = Maps.newTreeMap(Bytes.BYTES_COMPARATOR);
        for (byte[] row : rows) {
            NavigableMap<byte[], byte[]> values = Maps.newTreeMap(Bytes.BYTES_COMPARATOR);
            values.put(stateColumnName, DUMMY_STATE_CONTENT);
            changes.put(row, values);
        }
        tableCore.undo(changes, KeyValue.LATEST_TIMESTAMP);
    }

    @Override
    protected StateScanner scanStates(byte[] startRow, byte[] stopRow) throws IOException {
        final Scanner scanner = tableCore.scan(startRow, stopRow, null, null, Transaction.ALL_VISIBLE_LATEST);
        return new StateScanner() {

            private Row pair;

            @Override
            public boolean nextStateRow() throws IOException {
                pair = scanner.next();
                return pair != null;
            }

            @Override
            public byte[] getRow() {
                return pair.getRow();
            }

            @Override
            public byte[] getState() {
                return pair.getColumns().get(stateColumnName);
            }

            @Override
            public void close() throws IOException {
                scanner.close();
            }
        };
    }
}