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.bookkeeper.stream.storage.impl.cluster;
  
  import com.google.common.collect.Maps;
  import java.util.Map;
  import java.util.Optional;
  import java.util.concurrent.Executor;
  import java.util.function.Consumer;
  import lombok.Data;
  import org.apache.bookkeeper.stream.proto.cluster.ClusterAssignmentData;
  import org.apache.bookkeeper.stream.proto.cluster.ClusterMetadata;
  import org.apache.bookkeeper.stream.storage.api.cluster.ClusterMetadataStore;
  
  /**
   * An in-memory implementation of {@link ClusterMetadataStore}.
   */
  public class InMemClusterMetadataStore implements ClusterMetadataStore {
  
      @Data
      private static class WatcherAndExecutor {
          private final Consumer<Void> watcher;
          private final Executor executor;
      }
  
      private final Map<Consumer<Void>, WatcherAndExecutor> watchers;
  
      private ClusterMetadata metadata;
      private ClusterAssignmentData assignmentData;
  
      InMemClusterMetadataStore(int numStorageContainers) {
          this.watchers = Maps.newHashMap();
          initializeCluster(numStorageContainers);
      }
  
      synchronized int getNumWatchers() {
          return watchers.size();
      }
  
      @Override
      public synchronized boolean initializeCluster(int numStorageContainers,
                                                 Optional<String> segmentStorePath) {
          this.metadata = ClusterMetadata.newBuilder()
              .setNumStorageContainers(numStorageContainers)
              .build();
          this.assignmentData = ClusterAssignmentData.newBuilder().build();
          return true;
      }
  
      @Override
      public synchronized ClusterAssignmentData getClusterAssignmentData() {
          return assignmentData;
      }
  
      @Override
      public synchronized void updateClusterAssignmentData(ClusterAssignmentData assignmentData) {
          this.assignmentData = assignmentData;
          watchers.values().forEach(wae -> wae.executor.execute(() -> wae.watcher.accept(null)));
      }
  
      @Override
      public synchronized void watchClusterAssignmentData(Consumer<Void> watcher, Executor executor) {
          WatcherAndExecutor wae = watchers.get(watcher);
          if (null == wae) {
              wae = new WatcherAndExecutor(watcher, executor);
              watchers.put(watcher, wae);
          }
      }
  
      @Override
      public synchronized void unwatchClusterAssignmentData(Consumer<Void> watcher) {
          watchers.remove(watcher);
      }
  
      @Override
      public synchronized ClusterMetadata getClusterMetadata() {
          return metadata;
      }
  
      @Override
      public synchronized void updateClusterMetadata(ClusterMetadata clusterMetadata) {
          this.metadata = clusterMetadata;
      }
  
      @Override
      public void close() {
          // no-op
      }
  }
  