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;
  
  import org.apache.kafka.common.metrics.Sensor;
  import org.apache.kafka.streams.KeyValue;
  import org.apache.kafka.streams.kstream.ValueJoinerWithKey;
  import org.apache.kafka.streams.kstream.internals.KStreamImplJoin.TimeTracker;
  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.internals.StoreFactory;
  import org.apache.kafka.streams.processor.internals.StoreFactory.FactoryWrappingStoreBuilder;
  import org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl;
  import org.apache.kafka.streams.state.StoreBuilder;
  import org.apache.kafka.streams.state.WindowStore;
  import org.apache.kafka.streams.state.WindowStoreIterator;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.Collections;
  import java.util.Set;
  
  import static org.apache.kafka.streams.processor.internals.metrics.TaskMetrics.droppedRecordsSensor;
  
  class KStreamKStreamSelfJoin<K, V1, V2, VOut> implements ProcessorSupplier<K, V1, K, VOut> {
      private static final Logger LOG = LoggerFactory.getLogger(KStreamKStreamSelfJoin.class);
  
      private final StoreFactory windowStoreFactory;
      private final long joinThisBeforeMs;
      private final long joinThisAfterMs;
      private final long joinOtherBeforeMs;
      private final long joinOtherAfterMs;
      private final long retentionPeriod;
      private final ValueJoinerWithKey<? super K, ? super V1, ? super V2, ? extends VOut> joinerThis;
  
      KStreamKStreamSelfJoin(final StoreFactory windowStoreFactory,
                             final JoinWindowsInternal windows,
                             final ValueJoinerWithKey<? super K, ? super V1, ? super V2, ? extends VOut> joinerThis,
                             final long retentionPeriod) {
          this.windowStoreFactory = windowStoreFactory;
          this.joinThisBeforeMs = windows.beforeMs;
          this.joinThisAfterMs = windows.afterMs;
          this.joinOtherBeforeMs = windows.afterMs;
          this.joinOtherAfterMs = windows.beforeMs;
          this.joinerThis = joinerThis;
          this.retentionPeriod = retentionPeriod;
      }
  
      @Override
      public Set<StoreBuilder<?>> stores() {
          return Collections.singleton(new FactoryWrappingStoreBuilder<>(windowStoreFactory));
      }
  
      @Override
      public Processor<K, V1, K, VOut> get() {
          return new KStreamKStreamSelfJoinProcessor();
      }
  
      private class KStreamKStreamSelfJoinProcessor extends ContextualProcessor<K, V1, K, VOut> {
          private final TimeTracker timeTracker = new TimeTracker();
          private WindowStore<K, V2> windowStore;
          private Sensor droppedRecordsSensor;
  
          @Override
          public void init(final ProcessorContext<K, VOut> context) {
              super.init(context);
  
              final StreamsMetricsImpl metrics = (StreamsMetricsImpl) context.metrics();
              droppedRecordsSensor = droppedRecordsSensor(Thread.currentThread().getName(), context.taskId().toString(), metrics);
              windowStore = context.getStateStore(windowStoreFactory.storeName());
          }
  
          @SuppressWarnings("unchecked")
          @Override
          public void process(final Record<K, V1> record) {
              if (StreamStreamJoinUtil.skipRecord(record, LOG, droppedRecordsSensor, context())) {
                  return;
              }
  
              final long inputRecordTimestamp = record.timestamp();
              long timeFrom = Math.max(0L, inputRecordTimestamp - joinThisBeforeMs);
              long timeTo = Math.max(0L, inputRecordTimestamp + joinThisAfterMs);
              boolean emittedJoinWithSelf = false;
              final Record<K, ? extends VOut> selfRecord = record
                  .withValue(joinerThis.apply(record.key(), record.value(), (V2) record.value()))
                  .withTimestamp(inputRecordTimestamp);
              timeTracker.advanceStreamTime(inputRecordTimestamp);
              // We emit the self record only if it isn't expired.
              final boolean emitSelfRecord = inputRecordTimestamp > timeTracker.streamTime - retentionPeriod + 1;
  
              // Join current record with other
              try (final WindowStoreIterator<V2> iter = windowStore.fetch(record.key(), timeFrom, timeTo)) {
                  while (iter.hasNext()) {
                      final KeyValue<Long, V2> otherRecord = iter.next();
                      final long otherRecordTimestamp = otherRecord.key;
  
                      // Join this with other
                      context().forward(
                          record.withValue(joinerThis.apply(
                                  record.key(), record.value(), otherRecord.value))
                              .withTimestamp(Math.max(inputRecordTimestamp, otherRecordTimestamp)));
                  }
              }
  
              // Needs to be in a different loop to ensure correct ordering of records where
              // correct ordering means it matches the output of an inner join.
              timeFrom = Math.max(0L, inputRecordTimestamp - joinOtherBeforeMs);
              timeTo = Math.max(0L, inputRecordTimestamp + joinOtherAfterMs);
              try (final WindowStoreIterator<V2> iter2 = windowStore.fetch(record.key(), timeFrom, timeTo)) {
                  while (iter2.hasNext()) {
                      final KeyValue<Long, V2> otherRecord = iter2.next();
                      final long otherRecordTimestamp = otherRecord.key;
                      final long maxRecordTimestamp = Math.max(inputRecordTimestamp, otherRecordTimestamp);
  
                      // This is needed so that output records follow timestamp order
                      // Join this with self
                      if (inputRecordTimestamp < maxRecordTimestamp && !emittedJoinWithSelf && emitSelfRecord) {
                          emittedJoinWithSelf = true;
                          context().forward(selfRecord);
                      }
  
                      // Join other with current record
                      context().forward(
                          record
                              .withValue(joinerThis.apply(record.key(), (V1) otherRecord.value, (V2) record.value()))
                              .withTimestamp(Math.max(inputRecordTimestamp, otherRecordTimestamp)));
                  }
              }
  
              // Join this with self
              if (!emittedJoinWithSelf && emitSelfRecord) {
                  context().forward(selfRecord);
              }
          }
      }
  }
  