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.metrics.Sensor;
  import org.apache.kafka.common.utils.Bytes;
  import org.apache.kafka.streams.KeyValue;
  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.KeyValueIterator;
  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.nio.ByteBuffer;
  import java.util.Collections;
  import java.util.Set;
  
  public class ForeignTableJoinProcessorSupplier<KLeft, KRight, VRight>
      implements ProcessorSupplier<KRight, Change<VRight>, KLeft, SubscriptionResponseWrapper<VRight>> {
  
      private static final Logger LOG = LoggerFactory.getLogger(ForeignTableJoinProcessorSupplier.class);
      private final StoreFactory subscriptionStoreFactory;
      private final CombinedKeySchema<KRight, KLeft> keySchema;
      private boolean useVersionedSemantics = false;
  
      public ForeignTableJoinProcessorSupplier(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, Change<VRight>, KLeft, SubscriptionResponseWrapper<VRight>> get() {
          return new KTableKTableJoinProcessor();
      }
  
      public void setUseVersionedSemantics(final boolean useVersionedSemantics) {
          this.useVersionedSemantics = useVersionedSemantics;
      }
  
      // VisibleForTesting
      public boolean isUseVersionedSemantics() {
          return useVersionedSemantics;
      }
  
      private final class KTableKTableJoinProcessor extends ContextualProcessor<KRight, Change<VRight>, KLeft, SubscriptionResponseWrapper<VRight>> {
          private Sensor droppedRecordsSensor;
          private TimestampedKeyValueStore<Bytes, SubscriptionWrapper<KLeft>> subscriptionStore;
  
          @Override
          public void init(final ProcessorContext<KLeft, SubscriptionResponseWrapper<VRight>> context) {
              super.init(context);
              final InternalProcessorContext<?, ?> internalProcessorContext = (InternalProcessorContext<?, ?>) context;
              droppedRecordsSensor = TaskMetrics.droppedRecordsSensor(
                  Thread.currentThread().getName(),
                  internalProcessorContext.taskId().toString(),
                  internalProcessorContext.metrics()
              );
              subscriptionStore = internalProcessorContext.getStateStore(subscriptionStoreFactory.storeName());
          }
  
          @Override
          public void process(final Record<KRight, Change<VRight>> record) {
              // if the key is null, we do not need to proceed aggregating
              // the record with the table
              if (record.key() == null) {
                  if (context().recordMetadata().isPresent()) {
                      final RecordMetadata recordMetadata = context().recordMetadata().get();
                      LOG.warn(
                          "Skipping record due to null key. "
                              + "topic=[{}] partition=[{}] offset=[{}]",
                          recordMetadata.topic(), recordMetadata.partition(), recordMetadata.offset()
                      );
                  } else {
                      LOG.warn(
                          "Skipping record due to null key. Topic, partition, and offset not known."
                      );
                  }
                  droppedRecordsSensor.record();
                  return;
              }
  
              // drop out-of-order records from versioned tables (cf. KIP-914)
              if (useVersionedSemantics && !record.value().isLatest) {
                  LOG.info("Skipping out-of-order record from versioned table while performing table-table join.");
                  droppedRecordsSensor.record();
                  return;
              }
  
              final Bytes prefixBytes = keySchema.prefixBytes(record.key());
  
              //Perform the prefixScan and propagate the results
              try (final KeyValueIterator<Bytes, ValueAndTimestamp<SubscriptionWrapper<KLeft>>> prefixScanResults =
                       subscriptionStore.range(prefixBytes, Bytes.increment(prefixBytes))) {
  
                  while (prefixScanResults.hasNext()) {
                      final KeyValue<Bytes, ValueAndTimestamp<SubscriptionWrapper<KLeft>>> next = prefixScanResults.next();
                      // have to check the prefix because the range end is inclusive :(
                      if (prefixEquals(next.key.get(), prefixBytes.get())) {
                          final CombinedKey<KRight, KLeft> combinedKey = keySchema.fromBytes(next.key);
                          context().forward(
                              record.withKey(combinedKey.primaryKey())
                                  .withValue(new SubscriptionResponseWrapper<>(
                                      next.value.value().hash(),
                                      record.value().newValue,
                                      next.value.value().primaryPartition()))
                          );
                      }
                  }
              }
          }
  
          private boolean prefixEquals(final byte[] x, final byte[] y) {
              final int min = Math.min(x.length, y.length);
              final ByteBuffer xSlice = ByteBuffer.wrap(x, 0, min);
              final ByteBuffer ySlice = ByteBuffer.wrap(y, 0, min);
              return xSlice.equals(ySlice);
          }
      }
  }
  