kafka ChangeLoggingKeyValueBytesStore 源码

kafka ChangeLoggingKeyValueBytesStore 代码

文件路径：/streams/src/main/java/org/apache/kafka/streams/state/internals/ChangeLoggingKeyValueBytesStore.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.processor.ProcessorContext;
import org.apache.kafka.streams.processor.StateStore;
import org.apache.kafka.streams.processor.StateStoreContext;
import org.apache.kafka.streams.processor.internals.InternalProcessorContext;
import org.apache.kafka.streams.state.KeyValueIterator;
import org.apache.kafka.streams.state.KeyValueStore;

import java.util.List;

import static org.apache.kafka.streams.processor.internals.ProcessorContextUtils.asInternalProcessorContext;

public class ChangeLoggingKeyValueBytesStore
        extends WrappedStateStore<KeyValueStore<Bytes, byte[]>, byte[], byte[]>
        implements KeyValueStore<Bytes, byte[]> {

    InternalProcessorContext context;

    ChangeLoggingKeyValueBytesStore(final KeyValueStore<Bytes, byte[]> inner) {
        super(inner);
    }

    @Deprecated
    @Override
    public void init(final ProcessorContext context,
                     final StateStore root) {
        this.context = asInternalProcessorContext(context);
        super.init(context, root);
        maybeSetEvictionListener();
    }

    @Override
    public void init(final StateStoreContext context,
                     final StateStore root) {
        this.context = asInternalProcessorContext(context);
        super.init(context, root);
        maybeSetEvictionListener();
    }

    private void maybeSetEvictionListener() {
        // if the inner store is an LRU cache, add the eviction listener to log removed record
        if (wrapped() instanceof MemoryLRUCache) {
            ((MemoryLRUCache) wrapped()).setWhenEldestRemoved((key, value) -> {
                // pass null to indicate removal
                log(key, null);
            });
        }
    }

    @Override
    public long approximateNumEntries() {
        return wrapped().approximateNumEntries();
    }

    @Override
    public void put(final Bytes key,
                    final byte[] value) {
        wrapped().put(key, value);
        log(key, value);
    }

    @Override
    public byte[] putIfAbsent(final Bytes key,
                              final byte[] value) {
        final byte[] previous = wrapped().putIfAbsent(key, value);
        if (previous == null) {
            // then it was absent
            log(key, value);
        }
        return previous;
    }

    @Override
    public void putAll(final List<KeyValue<Bytes, byte[]>> entries) {
        wrapped().putAll(entries);
        for (final KeyValue<Bytes, byte[]> entry : entries) {
            log(entry.key, entry.value);
        }
    }

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

    @Override
    public byte[] delete(final Bytes key) {
        final byte[] oldValue = wrapped().delete(key);
        log(key, null);
        return oldValue;
    }

    @Override
    public byte[] get(final Bytes key) {
        return wrapped().get(key);
    }

    @Override
    public KeyValueIterator<Bytes, byte[]> range(final Bytes from,
                                                 final Bytes to) {
        return wrapped().range(from, to);
    }

    @Override
    public KeyValueIterator<Bytes, byte[]> reverseRange(final Bytes from,
                                                        final Bytes to) {
        return wrapped().reverseRange(from, to);
    }

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

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

    void log(final Bytes key, final byte[] value) {
        context.logChange(name(), key, value, context.timestamp(), wrapped().getPosition());
    }
}

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