content: /*
   * 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.kstream.internals.foreignkeyjoin;
  
  import org.apache.kafka.common.errors.UnsupportedVersionException;
  import org.apache.kafka.common.metrics.Sensor;
  import org.apache.kafka.common.utils.Bytes;
  import org.apache.kafka.streams.kstream.internals.Change;
  import org.apache.kafka.streams.processor.api.ContextualProcessor;
  import org.apache.kafka.streams.processor.api.Processor;
  import org.apache.kafka.streams.processor.api.ProcessorContext;
  import org.apache.kafka.streams.processor.api.ProcessorSupplier;
  import org.apache.kafka.streams.processor.api.Record;
  import org.apache.kafka.streams.processor.api.RecordMetadata;
  import org.apache.kafka.streams.processor.internals.InternalProcessorContext;
  import org.apache.kafka.streams.processor.internals.StoreFactory;
  import org.apache.kafka.streams.processor.internals.StoreFactory.FactoryWrappingStoreBuilder;
  import org.apache.kafka.streams.processor.internals.metrics.TaskMetrics;
  import org.apache.kafka.streams.state.StoreBuilder;
  import org.apache.kafka.streams.state.TimestampedKeyValueStore;
  import org.apache.kafka.streams.state.ValueAndTimestamp;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.Collections;
  import java.util.Set;
  
  public class SubscriptionReceiveProcessorSupplier<KLeft, KRight>
      implements ProcessorSupplier<KRight, SubscriptionWrapper<KLeft>, CombinedKey<KRight, KLeft>, Change<ValueAndTimestamp<SubscriptionWrapper<KLeft>>>> {
  
      private static final Logger LOG = LoggerFactory.getLogger(SubscriptionReceiveProcessorSupplier.class);
  
      private final StoreFactory subscriptionStoreFactory;
      private final CombinedKeySchema<KRight, KLeft> keySchema;
  
      public SubscriptionReceiveProcessorSupplier(final StoreFactory subscriptionStoreFactory,
                                                  final CombinedKeySchema<KRight, KLeft> keySchema) {
          this.subscriptionStoreFactory = subscriptionStoreFactory;
          this.keySchema = keySchema;
      }
  
      @Override
      public Set<StoreBuilder<?>> stores() {
          return Collections.singleton(new FactoryWrappingStoreBuilder<>(subscriptionStoreFactory));
      }
  
      @Override
      public Processor<KRight, SubscriptionWrapper<KLeft>, CombinedKey<KRight, KLeft>, Change<ValueAndTimestamp<SubscriptionWrapper<KLeft>>>> get() {
          return new ContextualProcessor<>() {
              private TimestampedKeyValueStore<Bytes, SubscriptionWrapper<KLeft>> store;
              private Sensor droppedRecordsSensor;
  
              @Override
              public void init(final ProcessorContext<CombinedKey<KRight, KLeft>, Change<ValueAndTimestamp<SubscriptionWrapper<KLeft>>>> context) {
                  super.init(context);
                  final InternalProcessorContext<?, ?> internalProcessorContext = (InternalProcessorContext<?, ?>) context;
  
                  droppedRecordsSensor = TaskMetrics.droppedRecordsSensor(
                      Thread.currentThread().getName(),
                      internalProcessorContext.taskId().toString(),
                      internalProcessorContext.metrics()
                  );
                  store = internalProcessorContext.getStateStore(subscriptionStoreFactory.storeName());
  
                  keySchema.init(context);
              }
  
              @Override
              public void process(final Record<KRight, SubscriptionWrapper<KLeft>> record) {
                  if (record.key() == null && !SubscriptionWrapper.Instruction.PROPAGATE_NULL_IF_NO_FK_VAL_AVAILABLE.equals(record.value().instruction())) {
                      dropRecord();
                      return;
                  }
                  if (record.value().version() > SubscriptionWrapper.CURRENT_VERSION) {
                      //Guard against modifications to SubscriptionWrapper. Need to ensure that there is compatibility
                      //with previous versions to enable rolling upgrades. Must develop a strategy for upgrading
                      //from older SubscriptionWrapper versions to newer versions.
                      throw new UnsupportedVersionException("SubscriptionWrapper is of an incompatible version.");
                  }
                  context().forward(
                      record.withKey(new CombinedKey<>(record.key(), record.value().primaryKey()))
                          .withValue(inferChange(record))
                          .withTimestamp(record.timestamp())
                  );
              }
  
              private Change<ValueAndTimestamp<SubscriptionWrapper<KLeft>>> inferChange(final Record<KRight, SubscriptionWrapper<KLeft>> record) {
                  if (record.key() == null) {
                      return new Change<>(ValueAndTimestamp.make(record.value(), record.timestamp()), null);
                  } else {
                      return inferBasedOnState(record);
                  }
              }
  
              private Change<ValueAndTimestamp<SubscriptionWrapper<KLeft>>> inferBasedOnState(final Record<KRight, SubscriptionWrapper<KLeft>> record) {
                  final Bytes subscriptionKey = keySchema.toBytes(record.key(), record.value().primaryKey());
  
                  final ValueAndTimestamp<SubscriptionWrapper<KLeft>> newValue = ValueAndTimestamp.make(record.value(), record.timestamp());
                  final ValueAndTimestamp<SubscriptionWrapper<KLeft>> oldValue = store.get(subscriptionKey);
  
                  //This store is used by the prefix scanner in ForeignTableJoinProcessorSupplier
                  if (record.value().instruction().equals(SubscriptionWrapper.Instruction.DELETE_KEY_AND_PROPAGATE) ||
                      record.value().instruction().equals(SubscriptionWrapper.Instruction.DELETE_KEY_NO_PROPAGATE)) {
                      store.delete(subscriptionKey);
                  } else {
                      store.put(subscriptionKey, newValue);
                  }
                  return new Change<>(newValue, oldValue);
              }
  
              private void dropRecord() {
                  if (context().recordMetadata().isPresent()) {
                      final RecordMetadata recordMetadata = context().recordMetadata().get();
                      LOG.warn(
                          "Skipping record due to null foreign key. "
                              + "topic=[{}] partition=[{}] offset=[{}]",
                          recordMetadata.topic(), recordMetadata.partition(), recordMetadata.offset()
                      );
                  } else {
                      LOG.warn(
                          "Skipping record due to null foreign key. Topic, partition, and offset not known."
                      );
                  }
                  droppedRecordsSensor.record();
              }
          };
      }
  }