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.cassandra.service.paxos;
  
  import java.security.SecureRandom;
  import java.util.concurrent.ThreadLocalRandom;
  
  import org.apache.cassandra.service.ClientState;
  import org.apache.cassandra.service.paxos.Ballot.Flag;
  import org.apache.cassandra.utils.Shared;
  
  import static org.apache.cassandra.service.paxos.Ballot.atUnixMicrosWithLsb;
  import static org.apache.cassandra.utils.Shared.Scope.SIMULATION;
  
  @Shared(scope = SIMULATION)
  public interface BallotGenerator
  {
      static class Default implements BallotGenerator
      {
          private static final SecureRandom secureRandom = new SecureRandom();
  
          public Ballot atUnixMicros(long unixMicros, Flag flag)
          {
              return atUnixMicrosWithLsb(unixMicros, secureRandom.nextLong(), flag);
          }
  
          public Ballot next(long minUnixMicros, Flag flag)
          {
              long unixMicros = ClientState.getTimestampForPaxos(minUnixMicros);
              return atUnixMicros(unixMicros, flag);
          }
  
          public Ballot stale(long fromInMicros, long toInMicros, Flag flag)
          {
              long unixMicros = ThreadLocalRandom.current().nextLong(fromInMicros, toInMicros);
              return atUnixMicros(unixMicros, flag);
          }
  
          public long next(long minTimestamp)
          {
              return ClientState.getTimestampForPaxos(minTimestamp);
          }
  
          public long prevUnixMicros()
          {
              return ClientState.getLastTimestampMicros();
          }
      }
  
      static class Global
      {
          private static BallotGenerator instance = new Default();
          public static Ballot atUnixMicros(long unixMicros, Flag flag) { return instance.atUnixMicros(unixMicros, flag); }
          public static Ballot nextBallot(Flag flag) { return instance.next(Long.MIN_VALUE, flag); }
          public static Ballot nextBallot(long minUnixMicros, Flag flag) { return instance.next(minUnixMicros, flag); }
          public static Ballot staleBallot(long fromUnixMicros, long toUnixMicros, Flag flag) { return instance.stale(fromUnixMicros, toUnixMicros, flag); }
          public static long prevUnixMicros() { return instance.prevUnixMicros(); }
  
          public static void unsafeSet(BallotGenerator newInstance)
          {
              instance = newInstance;
          }
      }
  
      Ballot atUnixMicros(long unixMicros, Flag flag);
      Ballot next(long minUnixMicros, Flag flag);
      Ballot stale(long fromUnixMicros, long toUnixMicros, Flag flag);
      long prevUnixMicros();
  }