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.spark.translation;
  
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import org.apache.beam.runners.fnexecution.control.DefaultExecutableStageContext;
  import org.apache.beam.runners.fnexecution.control.ExecutableStageContext;
  import org.apache.beam.runners.fnexecution.control.ReferenceCountingExecutableStageContextFactory;
  import org.apache.beam.runners.fnexecution.provisioning.JobInfo;
  
  /**
   * Singleton class that contains one {@link ExecutableStageContext.Factory} per job. Assumes it is
   * safe to release the backing environment asynchronously.
   */
  public class SparkExecutableStageContextFactory implements ExecutableStageContext.Factory {
  
    private static final SparkExecutableStageContextFactory instance =
        new SparkExecutableStageContextFactory();
    // This map should only ever have a single element, as each job will have its own
    // classloader and therefore its own instance of SparkExecutableStageContextFactory. This
    // code supports multiple JobInfos in order to provide a sensible implementation of
    // Factory.get(JobInfo), which in theory could be called with different JobInfos.
    private static final ConcurrentMap<String, ExecutableStageContext.Factory> jobFactories =
        new ConcurrentHashMap<>();
  
    private SparkExecutableStageContextFactory() {}
  
    public static SparkExecutableStageContextFactory getInstance() {
      return instance;
    }
  
    @Override
    public ExecutableStageContext get(JobInfo jobInfo) {
      ExecutableStageContext.Factory jobFactory =
          jobFactories.computeIfAbsent(
              jobInfo.jobId(),
              k -> {
                return ReferenceCountingExecutableStageContextFactory.create(
                    DefaultExecutableStageContext::create,
                    // Always release environment asynchronously.
                    (caller) -> false);
              });
      return jobFactory.get(jobInfo);
    }
  }
  