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.routing;
  
  import com.google.common.annotations.VisibleForTesting;
  import java.util.concurrent.CompletableFuture;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.bookkeeper.clients.impl.internal.api.StorageServerClientManager;
  import org.apache.bookkeeper.clients.impl.routing.RangeRouter;
  import org.apache.bookkeeper.common.concurrent.FutureUtils;
  import org.apache.bookkeeper.common.router.BytesHashRouter;
  import org.apache.bookkeeper.stream.proto.RangeProperties;
  import org.apache.bookkeeper.util.collections.ConcurrentLongHashMap;
  
  /**
   * A default implementation of {@link RangeRoutingTable}.
   */
  @Slf4j
  public class RangeRoutingTableImpl implements RangeRoutingTable {
  
      private final StorageServerClientManager manager;
      private final ConcurrentLongHashMap<RangeRouter<byte[]>> ranges;
  
      // outstanding requests
      private final ConcurrentLongHashMap<CompletableFuture<RangeRouter<byte[]>>> outstandingUpdates;
  
      public RangeRoutingTableImpl(StorageServerClientManager manager) {
          this.manager = manager;
          this.ranges = ConcurrentLongHashMap.<RangeRouter<byte[]>>newBuilder().build();
          this.outstandingUpdates =
                  ConcurrentLongHashMap.<CompletableFuture<RangeRouter<byte[]>>>newBuilder().build();
      }
  
      @VisibleForTesting
      RangeRouter<byte[]> getRangeRouter(long streamId) {
          return ranges.get(streamId);
      }
  
      @Override
      public RangeProperties getRange(long streamId, byte[] routingKey) {
          RangeRouter<byte[]> router = ranges.get(streamId);
          if (null == router) {
              // trigger to fetch stream metadata, but return `null` since
              // the range router is not ready, let the client backoff and retry.
              fetchStreamRanges(streamId);
              return null;
          } else {
              return router.getRangeProperties(routingKey);
          }
      }
  
      @VisibleForTesting
      CompletableFuture<RangeRouter<byte[]>> getOutstandingFetchRequest(long streamId) {
          return outstandingUpdates.get(streamId);
      }
  
      private void fetchStreamRanges(long streamId) {
          if (null != outstandingUpdates.get(streamId)) {
              // there is already an outstanding fetch request, do nothing
              return;
          }
          final CompletableFuture<RangeRouter<byte[]>> newFetchFuture = new CompletableFuture<>();
          if (null != outstandingUpdates.put(streamId, newFetchFuture)) {
              // some one already triggers the fetch
              return;
          }
          FutureUtils.proxyTo(
              manager.openMetaRangeClient(streamId)
                  .thenCompose(metaRangeClient -> metaRangeClient.getActiveDataRanges())
                  .thenApply(hashStreamRanges -> {
                      RangeRouter<byte[]> router = new RangeRouter<>(BytesHashRouter.of());
                      router.setRanges(hashStreamRanges);
                      return router;
                  })
                  .whenComplete((router, cause) -> {
                      if (null == cause) {
                          ranges.put(streamId, router);
                      }
                      outstandingUpdates.remove(streamId, newFetchFuture);
                  }),
              newFetchFuture
          );
      }
  }
  