streams/src/main/java/org/apache/kafka/streams/state/internals/MeteredSessionStore.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.metrics.Sensor;
import org.apache.kafka.common.serialization.Serde;
import org.apache.kafka.common.utils.Bytes;
import org.apache.kafka.common.utils.Time;
import org.apache.kafka.streams.errors.ProcessorStateException;
import org.apache.kafka.streams.kstream.Windowed;
import org.apache.kafka.streams.kstream.internals.Change;
import org.apache.kafka.streams.kstream.internals.WrappingNullableUtils;
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.TaskId;
import org.apache.kafka.streams.processor.internals.InternalProcessorContext;
import org.apache.kafka.streams.processor.internals.ProcessorContextUtils;
import org.apache.kafka.streams.processor.internals.SerdeGetter;
import org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl;
import org.apache.kafka.streams.query.FailureReason;
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.query.WindowRangeQuery;
import org.apache.kafka.streams.query.internals.InternalQueryResultUtil;
import org.apache.kafka.streams.state.KeyValueIterator;
import org.apache.kafka.streams.state.SessionStore;
import org.apache.kafka.streams.state.StateSerdes;
import org.apache.kafka.streams.state.internals.StoreQueryUtils.QueryHandler;
import org.apache.kafka.streams.state.internals.metrics.StateStoreMetrics;

import java.util.Map;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicInteger;

import static org.apache.kafka.common.utils.Utils.mkEntry;
import static org.apache.kafka.common.utils.Utils.mkMap;
import static org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency;

public class MeteredSessionStore<K, V>
    extends WrappedStateStore<SessionStore<Bytes, byte[]>, Windowed<K>, V>
    implements SessionStore<K, V> {

    private final String metricsScope;
    private final Serde<K> keySerde;
    private final Serde<V> valueSerde;
    private final Time time;
    private StateSerdes<K, V> serdes;
    private StreamsMetricsImpl streamsMetrics;
    private Sensor putSensor;
    private Sensor fetchSensor;
    private Sensor flushSensor;
    private Sensor removeSensor;
    private Sensor e2eLatencySensor;
    private Sensor iteratorDurationSensor;
    private InternalProcessorContext<?, ?> context;
    private TaskId taskId;

    private AtomicInteger numOpenIterators = new AtomicInteger(0);

    @SuppressWarnings("rawtypes")
    private final Map<Class, QueryHandler> queryHandlers =
            mkMap(
                    mkEntry(
                            WindowRangeQuery.class,
                            (query, positionBound, config, store) -> runRangeQuery(query, positionBound, config)
                    )
            );


    MeteredSessionStore(final SessionStore<Bytes, byte[]> inner,
                        final String metricsScope,
                        final Serde<K> keySerde,
                        final Serde<V> valueSerde,
                        final Time time) {
        super(inner);
        this.metricsScope = metricsScope;
        this.keySerde = keySerde;
        this.valueSerde = valueSerde;
        this.time = time;
    }

    @Deprecated
    @Override
    public void init(final ProcessorContext context,
                     final StateStore root) {
        this.context = context instanceof InternalProcessorContext ? (InternalProcessorContext<?, ?>) context : null;
        taskId = context.taskId();
        initStoreSerde(context);
        streamsMetrics = (StreamsMetricsImpl) context.metrics();

        registerMetrics();
        final Sensor restoreSensor =
            StateStoreMetrics.restoreSensor(taskId.toString(), metricsScope, name(), streamsMetrics);

        // register and possibly restore the state from the logs
        maybeMeasureLatency(() -> super.init(context, root), time, restoreSensor);
    }

    @Override
    public void init(final StateStoreContext context,
                     final StateStore root) {
        this.context = context instanceof InternalProcessorContext ? (InternalProcessorContext<?, ?>) context : null;
        taskId = context.taskId();
        initStoreSerde(context);
        streamsMetrics = (StreamsMetricsImpl) context.metrics();

        registerMetrics();
        final Sensor restoreSensor =
            StateStoreMetrics.restoreSensor(taskId.toString(), metricsScope, name(), streamsMetrics);

        // register and possibly restore the state from the logs
        maybeMeasureLatency(() -> super.init(context, root), time, restoreSensor);
    }

    private void registerMetrics() {
        putSensor = StateStoreMetrics.putSensor(taskId.toString(), metricsScope, name(), streamsMetrics);
        fetchSensor = StateStoreMetrics.fetchSensor(taskId.toString(), metricsScope, name(), streamsMetrics);
        flushSensor = StateStoreMetrics.flushSensor(taskId.toString(), metricsScope, name(), streamsMetrics);
        removeSensor = StateStoreMetrics.removeSensor(taskId.toString(), metricsScope, name(), streamsMetrics);
        e2eLatencySensor = StateStoreMetrics.e2ELatencySensor(taskId.toString(), metricsScope, name(), streamsMetrics);
        iteratorDurationSensor = StateStoreMetrics.iteratorDurationSensor(taskId.toString(), metricsScope, name(), streamsMetrics);
        StateStoreMetrics.addNumOpenIteratorsGauge(taskId.toString(), metricsScope, name(), streamsMetrics,
                (config, now) -> numOpenIterators.get());
    }


    private void initStoreSerde(final ProcessorContext context) {
        final String storeName = name();
        final String changelogTopic = ProcessorContextUtils.changelogFor(context, storeName, Boolean.FALSE);
        serdes = new StateSerdes<>(
            changelogTopic,
            WrappingNullableUtils.prepareKeySerde(keySerde, new SerdeGetter(context)),
            WrappingNullableUtils.prepareValueSerde(valueSerde, new SerdeGetter(context))
        );
    }

    private void initStoreSerde(final StateStoreContext context) {
        final String storeName = name();
        final String changelogTopic = ProcessorContextUtils.changelogFor(context, storeName, Boolean.FALSE);
        serdes = new StateSerdes<>(
            changelogTopic,
            WrappingNullableUtils.prepareKeySerde(keySerde, new SerdeGetter(context)),
            WrappingNullableUtils.prepareValueSerde(valueSerde, new SerdeGetter(context))
        );
    }

    @SuppressWarnings("unchecked")
    @Override
    public boolean setFlushListener(final CacheFlushListener<Windowed<K>, V> listener,
                                    final boolean sendOldValues) {
        final SessionStore<Bytes, byte[]> wrapped = wrapped();
        if (wrapped instanceof CachedStateStore) {
            return ((CachedStateStore<byte[], byte[]>) wrapped).setFlushListener(
                record -> listener.apply(
                    record.withKey(SessionKeySchema.from(record.key(), serdes.keyDeserializer(), serdes.topic()))
                        .withValue(new Change<>(
                            record.value().newValue != null ? serdes.valueFrom(record.value().newValue) : null,
                            record.value().oldValue != null ? serdes.valueFrom(record.value().oldValue) : null,
                            record.value().isLatest
                        ))
                ),
                sendOldValues);
        }
        return false;
    }

    @Override
    public void put(final Windowed<K> sessionKey,
                    final V aggregate) {
        Objects.requireNonNull(sessionKey, "sessionKey can't be null");
        Objects.requireNonNull(sessionKey.key(), "sessionKey.key() can't be null");
        Objects.requireNonNull(sessionKey.window(), "sessionKey.window() can't be null");

        try {
            maybeMeasureLatency(
                () -> {
                    final Bytes key = keyBytes(sessionKey.key());
                    wrapped().put(new Windowed<>(key, sessionKey.window()), serdes.rawValue(aggregate));
                },
                time,
                putSensor
            );
            maybeRecordE2ELatency();
        } catch (final ProcessorStateException e) {
            final String message = String.format(e.getMessage(), sessionKey.key(), aggregate);
            throw new ProcessorStateException(message, e);
        }
    }

    @Override
    public void remove(final Windowed<K> sessionKey) {
        Objects.requireNonNull(sessionKey, "sessionKey can't be null");
        Objects.requireNonNull(sessionKey.key(), "sessionKey.key() can't be null");
        Objects.requireNonNull(sessionKey.window(), "sessionKey.window() can't be null");

        try {
            maybeMeasureLatency(
                () -> {
                    final Bytes key = keyBytes(sessionKey.key());
                    wrapped().remove(new Windowed<>(key, sessionKey.window()));
                },
                time,
                removeSensor
            );
        } catch (final ProcessorStateException e) {
            final String message = String.format(e.getMessage(), sessionKey.key());
            throw new ProcessorStateException(message, e);
        }
    }

    @Override
    public V fetchSession(final K key, final long earliestSessionEndTime, final long latestSessionStartTime) {
        Objects.requireNonNull(key, "key cannot be null");
        return maybeMeasureLatency(
            () -> {
                final Bytes bytesKey = keyBytes(key);
                final byte[] result = wrapped().fetchSession(
                    bytesKey,
                    earliestSessionEndTime,
                    latestSessionStartTime
                );
                if (result == null) {
                    return null;
                }
                return serdes.valueFrom(result);
            },
            time,
            fetchSensor
        );
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> fetch(final K key) {
        Objects.requireNonNull(key, "key cannot be null");
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().fetch(keyBytes(key)),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators);
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> backwardFetch(final K key) {
        Objects.requireNonNull(key, "key cannot be null");
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().backwardFetch(keyBytes(key)),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators
        );
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> fetch(final K keyFrom,
                                                  final K keyTo) {
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().fetch(keyBytes(keyFrom), keyBytes(keyTo)),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators);
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> backwardFetch(final K keyFrom,
                                                          final K keyTo) {
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().backwardFetch(keyBytes(keyFrom), keyBytes(keyTo)),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators
        );
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> findSessions(final K key,
                                                         final long earliestSessionEndTime,
                                                         final long latestSessionStartTime) {
        Objects.requireNonNull(key, "key cannot be null");
        final Bytes bytesKey = keyBytes(key);
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().findSessions(
                bytesKey,
                earliestSessionEndTime,
                latestSessionStartTime),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators);
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> backwardFindSessions(final K key,
                                                                 final long earliestSessionEndTime,
                                                                 final long latestSessionStartTime) {
        Objects.requireNonNull(key, "key cannot be null");
        final Bytes bytesKey = keyBytes(key);
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().backwardFindSessions(
                bytesKey,
                earliestSessionEndTime,
                latestSessionStartTime
            ),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators
        );
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> findSessions(final K keyFrom,
                                                         final K keyTo,
                                                         final long earliestSessionEndTime,
                                                         final long latestSessionStartTime) {
        final Bytes bytesKeyFrom = keyBytes(keyFrom);
        final Bytes bytesKeyTo = keyBytes(keyTo);
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().findSessions(
                bytesKeyFrom,
                bytesKeyTo,
                earliestSessionEndTime,
                latestSessionStartTime),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators);
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> findSessions(final long earliestSessionEndTime,
                                                         final long latestSessionEndTime) {
        return new MeteredWindowedKeyValueIterator<>(
                wrapped().findSessions(earliestSessionEndTime, latestSessionEndTime),
                fetchSensor,
                iteratorDurationSensor,
                streamsMetrics,
                serdes::keyFrom,
                serdes::valueFrom,
                time,
                numOpenIterators);
    }

    @Override
    public KeyValueIterator<Windowed<K>, V> backwardFindSessions(final K keyFrom,
                                                                 final K keyTo,
                                                                 final long earliestSessionEndTime,
                                                                 final long latestSessionStartTime) {
        final Bytes bytesKeyFrom = keyBytes(keyFrom);
        final Bytes bytesKeyTo = keyBytes(keyTo);
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().backwardFindSessions(
                bytesKeyFrom,
                bytesKeyTo,
                earliestSessionEndTime,
                latestSessionStartTime
            ),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators
        );
    }

    @Override
    public void flush() {
        maybeMeasureLatency(super::flush, time, flushSensor);
    }

    @Override
    public void close() {
        try {
            wrapped().close();
        } finally {
            streamsMetrics.removeAllStoreLevelSensorsAndMetrics(taskId.toString(), name());
        }
    }

    @SuppressWarnings("unchecked")
    @Override
    public <R> QueryResult<R> query(final Query<R> query,
                                    final PositionBound positionBound,
                                    final QueryConfig config) {
        final long start = time.nanoseconds();
        final QueryResult<R> result;

        final QueryHandler handler = queryHandlers.get(query.getClass());
        if (handler == null) {
            result = wrapped().query(query, positionBound, config);
            if (config.isCollectExecutionInfo()) {
                result.addExecutionInfo(
                    "Handled in " + getClass() + " in " + (time.nanoseconds() - start) + "ns");
            }
        } else {
            result = (QueryResult<R>) handler.apply(
                query,
                positionBound,
                config,
                this
            );
            if (config.isCollectExecutionInfo()) {
                result.addExecutionInfo(
                    "Handled in " + getClass() + " with serdes "
                        + serdes + " in " + (time.nanoseconds() - start) + "ns");
            }
        }
        return result;
    }

    @SuppressWarnings("unchecked")
    private <R> QueryResult<R> runRangeQuery(final Query<R> query,
                                             final PositionBound positionBound,
                                             final QueryConfig config) {
        final QueryResult<R> result;
        final WindowRangeQuery<K, V> typedQuery = (WindowRangeQuery<K, V>) query;
        if (typedQuery.getKey().isPresent()) {
            final WindowRangeQuery<Bytes, byte[]> rawKeyQuery =
                WindowRangeQuery.withKey(
                    Bytes.wrap(serdes.rawKey(typedQuery.getKey().get()))
                );
            final QueryResult<KeyValueIterator<Windowed<Bytes>, byte[]>> rawResult =
                wrapped().query(rawKeyQuery, positionBound, config);
            if (rawResult.isSuccess()) {
                final MeteredWindowedKeyValueIterator<K, V> typedResult =
                    new MeteredWindowedKeyValueIterator<>(
                        rawResult.getResult(),
                        fetchSensor,
                        iteratorDurationSensor,
                        streamsMetrics,
                        serdes::keyFrom,
                        StoreQueryUtils.getDeserializeValue(serdes, wrapped()),
                        time,
                        numOpenIterators
                    );
                final QueryResult<MeteredWindowedKeyValueIterator<K, V>> typedQueryResult =
                    InternalQueryResultUtil.copyAndSubstituteDeserializedResult(rawResult, typedResult);
                result = (QueryResult<R>) typedQueryResult;
            } else {
                // the generic type doesn't matter, since failed queries have no result set.
                result = (QueryResult<R>) rawResult;
            }
        } else {

            result = QueryResult.forFailure(
                FailureReason.UNKNOWN_QUERY_TYPE,
                "This store (" + getClass() + ") doesn't know how to"
                    + " execute the given query (" + query + ") because"
                    + " SessionStores only support WindowRangeQuery.withKey."
                    + " Contact the store maintainer if you need support"
                    + " for a new query type."
            );
        }
        return result;
    }

    private Bytes keyBytes(final K key) {
        return key == null ? null : Bytes.wrap(serdes.rawKey(key));
    }

    private void maybeRecordE2ELatency() {
        // Context is null if the provided context isn't an implementation of InternalProcessorContext.
        // In that case, we _can't_ get the current timestamp, so we don't record anything.
        if (e2eLatencySensor.shouldRecord() && context != null) {
            final long currentTime = time.milliseconds();
            final long e2eLatency =  currentTime - context.timestamp();
            e2eLatencySensor.record(e2eLatency, currentTime);
        }
    }
}