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.stress;
  
  import java.util.concurrent.atomic.AtomicLong;
  
  public interface WorkManager
  {
      // -1 indicates consumer should terminate
      int takePermits(int count);
  
      // signal all consumers to terminate
      void stop();
  
      static final class FixedWorkManager implements WorkManager
      {
  
          final AtomicLong permits;
  
          public FixedWorkManager(long permits)
          {
              this.permits = new AtomicLong(permits);
          }
  
          @Override
          public int takePermits(int count)
          {
              while (true)
              {
                  long cur = permits.get();
                  if (cur == 0)
                      return -1;
                  count = (int) Math.min(count, cur);
                  long next = cur - count;
                  if (permits.compareAndSet(cur, next))
                      return count;
              }
          }
  
          @Override
          public void stop()
          {
              permits.getAndSet(0);
          }
      }
  
      static final class ContinuousWorkManager implements WorkManager
      {
  
          volatile boolean stop = false;
  
          @Override
          public int takePermits(int count)
          {
              if (stop)
                  return -1;
              return count;
          }
  
          @Override
          public void stop()
          {
              stop = true;
          }
  
      }
  }
  