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.harness;
  
  import org.apache.beam.sdk.options.PipelineOptions;
  
  /**
   * A service interface for defining one-time initialization of the JVM during pipeline execution.
   *
   * <p>During pipeline execution, {@code onStartup} and {@code beforeProcessing} will be invoked at
   * the appropriate stage of execution after the JVM is launched. Currently this is only supported in
   * portable pipelines or when using Google Cloud Dataflow.
   *
   * <p>{@link java.util.ServiceLoader} is used to discover implementations of {@link JvmInitializer},
   * note that you will need to register your implementation with the appropriate resources to ensure
   * your code is executed. You can use a tool like {@link com.google.auto.service.AutoService} to
   * automate this.
   */
  public interface JvmInitializer {
  
    /**
     * Implement onStartup to run some custom initialization immediately after the JVM is launched for
     * pipeline execution.
     *
     * <p>In general users should prefer to implement {@code beforeProcessing} to perform custom
     * initialization so that basic services such as logging can be initialized first, but {@code
     * onStartup} is also provided if initialization absolutely needs to be run immediately after
     * starting.
     */
    default void onStartup() {}
  
    /**
     * Implement beforeProcessing to run some custom initialization after basic services such as
     * logging, but before data processing begins.
     *
     * @param options The pipeline options passed to the worker.
     */
    default void beforeProcessing(PipelineOptions options) {}
  }
  