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.bookie.datainteg;
  
  import static com.google.common.base.Preconditions.checkState;
  
  import com.google.common.collect.ImmutableList;
  import java.util.List;
  import java.util.stream.Collectors;
  import java.util.stream.IntStream;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Pregenerate the write sets. RoundRobinDistributionSchedule should really be doing this also.
   */
  class WriteSets {
      private static final Logger log = LoggerFactory.getLogger(WriteSets.class);
      private final int ensembleSize;
      private final ImmutableList<ImmutableList<Integer>> sets;
  
      WriteSets(List<Integer> preferredOrder,
                int ensembleSize,
                int writeQuorumSize) {
          this.ensembleSize = ensembleSize;
  
          ImmutableList.Builder<ImmutableList<Integer>> builder =
              new ImmutableList.Builder<ImmutableList<Integer>>();
          for (int i = 0; i < ensembleSize; i++) {
              builder.add(generateWriteSet(preferredOrder, ensembleSize, writeQuorumSize, i));
          }
          sets = builder.build();
      }
  
      WriteSets(int ensembleSize, int writeQuorumSize) {
          this(IntStream.range(0, ensembleSize).boxed().collect(Collectors.toList()),
               ensembleSize, writeQuorumSize);
      }
  
      ImmutableList<Integer> getForEntry(long entryId) {
          return sets.get((int) (entryId % ensembleSize));
      }
  
      static ImmutableList<Integer> generateWriteSet(List<Integer> preferredOrder,
                                                     int ensembleSize,
                                                     int writeQuorumSize,
                                                     int offset) {
          ImmutableList.Builder<Integer> builder =
              new ImmutableList.Builder<Integer> ();
          int firstIndex = offset;
          int lastIndex = (offset + writeQuorumSize - 1) % ensembleSize;
          for (Integer i : preferredOrder) {
              if (firstIndex <= lastIndex
                  && i >= firstIndex
                  && i <= lastIndex) {
                  builder.add(i);
              } else if (lastIndex < firstIndex
                         && (i <= lastIndex
                             || i >= firstIndex)) {
                  builder.add(i);
              }
          }
          ImmutableList<Integer> writeSet = builder.build();
  
          // writeSet may be one smaller than the configured write
          // set size if we are excluding ourself
          checkState(writeSet.size() == writeQuorumSize
                                   || (writeSet.size() == writeQuorumSize - 1));
          return writeSet;
      }
  }
  