kafka MemoryNavigableLRUCache 源码

kafka MemoryNavigableLRUCache 代码

文件路径：/streams/src/main/java/org/apache/kafka/streams/state/internals/MemoryNavigableLRUCache.java

/*
 * 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.kafka.streams.state.internals;

import org.apache.kafka.common.serialization.Serializer;
import org.apache.kafka.common.utils.Bytes;
import org.apache.kafka.streams.KeyValue;
import org.apache.kafka.streams.query.PositionBound;
import org.apache.kafka.streams.query.Query;
import org.apache.kafka.streams.query.QueryConfig;
import org.apache.kafka.streams.query.QueryResult;
import org.apache.kafka.streams.state.KeyValueIterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Iterator;
import java.util.Map;
import java.util.Objects;
import java.util.TreeMap;

public class MemoryNavigableLRUCache extends MemoryLRUCache {

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

    public MemoryNavigableLRUCache(final String name, final int maxCacheSize) {
        super(name, maxCacheSize);
    }

    @Override
    public KeyValueIterator<Bytes, byte[]> range(final Bytes from, final Bytes to) {
        if (Objects.nonNull(from) && Objects.nonNull(to) && from.compareTo(to) > 0) {
            LOG.warn("Returning empty iterator for fetch with invalid key range: from > to. " +
                    "This may be due to range arguments set in the wrong order, " +
                    "or serdes that don't preserve ordering when lexicographically comparing the serialized bytes. " +
                    "Note that the built-in numerical serdes do not follow this for negative numbers");
            return KeyValueIterators.emptyIterator();
        } else {
            final TreeMap<Bytes, byte[]> treeMap = toTreeMap();
            final Iterator<Bytes> keys = getIterator(treeMap, from, to, true);
            return new DelegatingPeekingKeyValueIterator<>(name(),
                    new MemoryNavigableLRUCache.CacheIterator(keys, treeMap));
        }
    }

    @Override
    public KeyValueIterator<Bytes, byte[]> reverseRange(final Bytes from, final Bytes to) {
        if (Objects.nonNull(from) && Objects.nonNull(to) && from.compareTo(to) > 0) {
            LOG.warn("Returning empty iterator for fetch with invalid key range: from > to. " +
                    "This may be due to range arguments set in the wrong order, " +
                    "or serdes that don't preserve ordering when lexicographically comparing the serialized bytes. " +
                    "Note that the built-in numerical serdes do not follow this for negative numbers");
            return KeyValueIterators.emptyIterator();
        } else {
            final TreeMap<Bytes, byte[]> treeMap = toTreeMap();
            final Iterator<Bytes> keys = getIterator(treeMap, from, to, false);
            return new DelegatingPeekingKeyValueIterator<>(name(),
                    new MemoryNavigableLRUCache.CacheIterator(keys, treeMap));
        }
    }

    private Iterator<Bytes> getIterator(final TreeMap<Bytes, byte[]> treeMap, final Bytes from, final Bytes to, final boolean forward) {
        if (from == null && to == null) {
            return forward ? treeMap.navigableKeySet().iterator() : treeMap.navigableKeySet().descendingIterator();
        } else if (from == null) {
            return forward ? treeMap.navigableKeySet().headSet(to, true).iterator() : treeMap.navigableKeySet().headSet(to, true).descendingIterator();
        } else if (to == null) {
            return forward ? treeMap.navigableKeySet().tailSet(from, true).iterator() : treeMap.navigableKeySet().tailSet(from, true).descendingIterator();
        } else {
            return forward ? treeMap.navigableKeySet().subSet(from, true, to, true).iterator() : treeMap.navigableKeySet().subSet(from, true, to, true).descendingIterator();
        }
    }

    @Override
    public <PS extends Serializer<P>, P> KeyValueIterator<Bytes, byte[]> prefixScan(final P prefix, final PS prefixKeySerializer) {

        final Bytes from = Bytes.wrap(prefixKeySerializer.serialize(null, prefix));
        final Bytes to = Bytes.increment(from);

        final TreeMap<Bytes, byte[]> treeMap = toTreeMap();

        return new DelegatingPeekingKeyValueIterator<>(
            name(),
            new MemoryNavigableLRUCache.CacheIterator(treeMap.subMap(from, true, to, false).keySet().iterator(), treeMap)
        );
    }

    @Override
    public  KeyValueIterator<Bytes, byte[]> all() {
        return range(null, null);
    }

    @Override
    public  KeyValueIterator<Bytes, byte[]> reverseAll() {
        return reverseRange(null, null);
    }

    private synchronized TreeMap<Bytes, byte[]> toTreeMap() {
        return new TreeMap<>(this.map);
    }

    @Override
    @SuppressWarnings("unchecked")
    public <R> QueryResult<R> query(
        final Query<R> query,
        final PositionBound positionBound,
        final QueryConfig config) {

        return StoreQueryUtils.handleBasicQueries(
            query,
            positionBound,
            config,
            this,
            getPosition(),
            context
        );
    }


    private static class CacheIterator implements KeyValueIterator<Bytes, byte[]> {
        private final Iterator<Bytes> keys;
        private final Map<Bytes, byte[]> entries;

        private CacheIterator(final Iterator<Bytes> keys, final Map<Bytes, byte[]> entries) {
            this.keys = keys;
            this.entries = entries;
        }

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

        @Override
        public KeyValue<Bytes, byte[]> next() {
            final Bytes lastKey = keys.next();
            return new KeyValue<>(lastKey, entries.get(lastKey));
        }

        @Override
        public void close() {
            // do nothing
        }

        @Override
        public Bytes peekNextKey() {
            throw new UnsupportedOperationException("peekNextKey not supported");
        }
    }
}

相关信息

kafka 源码目录

相关文章

kafka AbstractDualSchemaRocksDBSegmentedBytesStore 源码

kafka AbstractMergedSortedCacheStoreIterator 源码

kafka AbstractRocksDBSegmentedBytesStore 源码

kafka AbstractRocksDBTimeOrderedSegmentedBytesStore 源码

kafka AbstractSegments 源码

kafka AbstractStoreBuilder 源码

kafka BatchWritingStore 源码

kafka BlockBasedTableConfigWithAccessibleCache 源码

kafka BufferKey 源码

kafka BufferValue 源码