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.sdk.extensions.euphoria.core.translate;
  
  import static java.util.Objects.requireNonNull;
  
  import java.io.Serializable;
  import org.apache.beam.sdk.extensions.euphoria.core.client.accumulators.AccumulatorProvider;
  import org.apache.beam.sdk.extensions.euphoria.core.client.accumulators.Counter;
  import org.apache.beam.sdk.extensions.euphoria.core.client.accumulators.Histogram;
  import org.apache.beam.sdk.extensions.euphoria.core.client.accumulators.Timer;
  
  /** Instantiate accumulator provider on the first usage. Thus {@link Serializable}. */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class LazyAccumulatorProvider implements AccumulatorProvider, Serializable {
  
    private final Factory factory;
  
    private transient AccumulatorProvider accumulators;
  
    LazyAccumulatorProvider(Factory factory) {
      this.factory = requireNonNull(factory);
    }
  
    @Override
    public Counter getCounter(String name) {
      return getAccumulatorProvider().getCounter(name);
    }
  
    @Override
    public Counter getCounter(String namespace, String name) {
      return getAccumulatorProvider().getCounter(namespace, name);
    }
  
    @Override
    public Histogram getHistogram(String name) {
      return getAccumulatorProvider().getHistogram(name);
    }
  
    @Override
    public Histogram getHistogram(String namespace, String name) {
      return getAccumulatorProvider().getHistogram(namespace, name);
    }
  
    @Override
    public Timer getTimer(String name) {
      return getAccumulatorProvider().getTimer(name);
    }
  
    private AccumulatorProvider getAccumulatorProvider() {
      if (accumulators == null) {
        accumulators = factory.create();
      }
      return accumulators;
    }
  }
  