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.processor.internals.assignment;
  
  import org.apache.kafka.streams.processor.TaskId;
  import org.apache.kafka.streams.processor.assignment.KafkaStreamsState;
  import org.apache.kafka.streams.processor.assignment.ProcessId;
  import org.apache.kafka.streams.state.HostInfo;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.Arrays;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Optional;
  import java.util.Set;
  import java.util.SortedMap;
  import java.util.SortedSet;
  import java.util.TreeSet;
  import java.util.stream.Collectors;
  
  import static java.util.Collections.unmodifiableMap;
  import static java.util.Collections.unmodifiableSortedMap;
  import static java.util.Collections.unmodifiableSortedSet;
  import static java.util.Comparator.comparingLong;
  
  public class DefaultKafkaStreamsState implements KafkaStreamsState {
      private static final Logger LOG = LoggerFactory.getLogger(DefaultKafkaStreamsState.class);
  
      private final ProcessId processId;
      private final int numProcessingThreads;
      private final Map<String, String> clientTags;
      private final SortedSet<TaskId> previousActiveTasks;
      private final SortedSet<TaskId> previousStandbyTasks;
      private final SortedMap<String, Set<TaskId>> taskIdsByConsumer;
      private final Optional<HostInfo> hostInfo;
      private final Optional<Map<TaskId, Long>> taskLagTotals; // contains lag for all stateful tasks in the app topology
      private final Optional<String> rackId;
  
      public DefaultKafkaStreamsState(final ProcessId processId,
                                      final int numProcessingThreads,
                                      final Map<String, String> clientTags,
                                      final SortedSet<TaskId> previousActiveTasks,
                                      final SortedSet<TaskId> previousStandbyTasks,
                                      final SortedMap<String, Set<TaskId>> taskIdsByConsumer,
                                      final Optional<HostInfo> hostInfo,
                                      final Optional<Map<TaskId, Long>> taskLagTotals,
                                      final Optional<String> rackId) {
          this.processId = processId;
          this.numProcessingThreads = numProcessingThreads;
          this.clientTags = unmodifiableMap(clientTags);
          this.previousActiveTasks = unmodifiableSortedSet(previousActiveTasks);
          this.previousStandbyTasks = unmodifiableSortedSet(previousStandbyTasks);
          this.taskIdsByConsumer = unmodifiableSortedMap(taskIdsByConsumer);
          this.hostInfo = hostInfo;
          this.taskLagTotals = taskLagTotals;
          this.rackId = rackId;
      }
  
      @Override
      public ProcessId processId() {
          return processId;
      }
  
      @Override
      public int numProcessingThreads() {
          return numProcessingThreads;
      }
  
      @Override
      public SortedSet<String> consumerClientIds() {
          return new TreeSet<>(taskIdsByConsumer.keySet());
      }
  
      @Override
      public SortedSet<TaskId> previousActiveTasks() {
          return previousActiveTasks;
      }
  
      @Override
      public SortedSet<TaskId> previousStandbyTasks() {
          return previousStandbyTasks;
      }
  
      @Override
      public long lagFor(final TaskId task) {
          if (taskLagTotals.isEmpty()) {
              LOG.error("lagFor was called on a KafkaStreamsState {} that does not support lag computations.", processId);
              throw new UnsupportedOperationException("Lag computation was not requested for KafkaStreamsState with process " + processId);
          }
  
          final Long totalLag = taskLagTotals.get().get(task);
          if (totalLag == null) {
              LOG.error("Task lag lookup failed: {} not in {}", task,
                  Arrays.toString(taskLagTotals.get().keySet().toArray()));
              throw new IllegalStateException("Tried to lookup lag for unknown task " + task);
          }
          return totalLag;
      }
  
      @Override
      public SortedSet<TaskId> prevTasksByLag(final String consumerClientId) {
          if (taskLagTotals.isEmpty()) {
              LOG.error("prevTasksByLag was called on a KafkaStreamsState {} that does not support lag computations.", processId);
              throw new UnsupportedOperationException("Lag computation was not requested for KafkaStreamsState with process " + processId);
          }
  
          final SortedSet<TaskId> prevTasksByLag =
              new TreeSet<>(comparingLong(this::lagFor).thenComparing(TaskId::compareTo));
          final Set<TaskId> prevOwnedStatefulTasks = taskIdsByConsumer.containsKey(consumerClientId)
              ? taskIdsByConsumer.get(consumerClientId) : new HashSet<>();
          for (final TaskId task : prevOwnedStatefulTasks) {
              if (taskLagTotals.get().containsKey(task)) {
                  prevTasksByLag.add(task);
              } else {
                  LOG.debug(
                      "Skipping previous task {} since it's not part of the current assignment",
                      task
                  );
              }
          }
          return prevTasksByLag;
      }
  
      @Override
      public Map<TaskId, Long> statefulTasksToLagSums() {
          if (taskLagTotals.isEmpty()) {
              LOG.error("statefulTasksToLagSums was called on a KafkaStreamsState {} that does not support lag computations.", processId);
              throw new UnsupportedOperationException("Lag computation was not requested for KafkaStreamsState with process " + processId);
          }
  
          return taskLagTotals.get().keySet()
              .stream()
              .collect(Collectors.toMap(taskId -> taskId, this::lagFor));
      }
  
      @Override
      public Optional<HostInfo> hostInfo() {
          return hostInfo;
      }
  
      @Override
      public Map<String, String> clientTags() {
          return clientTags;
      }
  
      @Override
      public Optional<String> rackId() {
          return rackId;
      }
  }
  