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.beam.runners.dataflow.worker.windmill.work.budget;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.math.LongMath.divide;
  
  import java.math.RoundingMode;
  import org.apache.beam.sdk.annotations.Internal;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableCollection;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /** Evenly distributes the provided budget across the available {@link GetWorkBudgetSpender}(s). */
  @Internal
  final class EvenGetWorkBudgetDistributor implements GetWorkBudgetDistributor {
    private static final Logger LOG = LoggerFactory.getLogger(EvenGetWorkBudgetDistributor.class);
  
    @Override
    public <T extends GetWorkBudgetSpender> void distributeBudget(
        ImmutableCollection<T> budgetSpenders, GetWorkBudget getWorkBudget) {
      if (budgetSpenders.isEmpty()) {
        LOG.debug("Cannot distribute budget to no owners.");
        return;
      }
  
      if (getWorkBudget.equals(GetWorkBudget.noBudget())) {
        LOG.debug("Cannot distribute 0 budget.");
        return;
      }
  
      GetWorkBudget budgetPerStream = computeDesiredPerStreamBudget(budgetSpenders, getWorkBudget);
      budgetSpenders.forEach(getWorkBudgetSpender -> getWorkBudgetSpender.setBudget(budgetPerStream));
    }
  
    private <T extends GetWorkBudgetSpender> GetWorkBudget computeDesiredPerStreamBudget(
        ImmutableCollection<T> streams, GetWorkBudget totalGetWorkBudget) {
      return GetWorkBudget.builder()
          .setItems(divide(totalGetWorkBudget.items(), streams.size(), RoundingMode.CEILING))
          .setBytes(divide(totalGetWorkBudget.bytes(), streams.size(), RoundingMode.CEILING))
          .build();
    }
  }
  