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.bifromq.basescheduler;
  
  import org.apache.bifromq.basehookloader.BaseHookLoader;
  import org.apache.bifromq.basescheduler.spi.ICapacityEstimator;
  import org.apache.bifromq.basescheduler.spi.ICapacityEstimatorFactory;
  import java.util.Map;
  import lombok.extern.slf4j.Slf4j;
  
  @Slf4j
  class CapacityEstimatorFactory implements ICapacityEstimatorFactory {
      public static final ICapacityEstimatorFactory INSTANCE = new CapacityEstimatorFactory();
  
      private final ICapacityEstimatorFactory delegate;
  
      private CapacityEstimatorFactory() {
          Map<String, ICapacityEstimatorFactory> factoryMap = BaseHookLoader.load(ICapacityEstimatorFactory.class);
          if (factoryMap.isEmpty()) {
              delegate = FallbackFactory.INSTANCE;
          } else {
              delegate = factoryMap.values().iterator().next();
          }
      }
  
      @Override
      public ICapacityEstimator create(String name) {
          try {
              ICapacityEstimator estimator = delegate.create(name);
              if (estimator == null) {
                  return FallbackFactory.INSTANCE.create(name);
              }
              return estimator;
          } catch (Throwable e) {
              log.error("Failed to create pipelineDepthEstimator: scheduler={}", name, e);
              return FallbackFactory.INSTANCE.create(name);
          }
      }
  
      private static class FallbackCapacityEstimator implements ICapacityEstimator {
          private static final ICapacityEstimator INSTANCE = new FallbackCapacityEstimator();
  
          @Override
          public void record(int batchSize, long latencyNs) {
          }
  
          @Override
          public int maxPipelineDepth() {
              return 1;
          }
  
          @Override
          public int maxBatchSize() {
              return Integer.MAX_VALUE;
          }
      }
  
      private static class FallbackFactory implements ICapacityEstimatorFactory {
          private static final ICapacityEstimatorFactory INSTANCE = new FallbackFactory();
  
          @Override
          public ICapacityEstimator create(String name) {
              return FallbackCapacityEstimator.INSTANCE;
          }
      }
  }
  