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;
  
  import com.google.api.services.dataflow.model.PerWorkerMetrics;
  import com.google.api.services.dataflow.model.StreamingScalingReport;
  import com.google.api.services.dataflow.model.WorkItem;
  import com.google.api.services.dataflow.model.WorkItemServiceState;
  import com.google.api.services.dataflow.model.WorkItemStatus;
  import com.google.api.services.dataflow.model.WorkerMessage;
  import com.google.api.services.dataflow.model.WorkerMessageResponse;
  import java.io.IOException;
  import java.util.List;
  import java.util.Optional;
  
  /** Abstract base class describing a client for WorkItem work units. */
  public interface WorkUnitClient {
    /**
     * Returns a new WorkItem unit for this Worker to work on or null if no work item is available.
     */
    Optional<WorkItem> getWorkItem() throws IOException;
  
    /**
     * Returns a new global streaming config WorkItem, or returns {@link Optional#empty()} if no work
     * was found.
     */
    Optional<WorkItem> getGlobalStreamingConfigWorkItem() throws IOException;
  
    /**
     * Returns a streaming config WorkItem for the given computation, or returns {@link
     * Optional#empty()} if no work was found.
     */
    Optional<WorkItem> getStreamingConfigWorkItem(String computationId) throws IOException;
  
    /**
     * Reports a {@link WorkItemStatus} for an assigned {@link WorkItem}.
     *
     * @param workItemStatus the status to report
     * @return a {@link WorkItemServiceState} (e.g. a new stop position)
     */
    WorkItemServiceState reportWorkItemStatus(WorkItemStatus workItemStatus) throws IOException;
  
    /**
     * Creates a {@link WorkerMessage} containing the given Streaming Scaling Report
     *
     * @param report the StreamingScalingReport containing autoscaling metrics
     * @return a {@link WorkerMessage}
     */
    WorkerMessage createWorkerMessageFromStreamingScalingReport(StreamingScalingReport report);
  
    /**
     * Creates a {@link WorkerMessage} containing the given PerWorkerMetrics
     *
     * @param metrics Metric updates to send to the backend.
     * @return a {@link WorkerMessage}
     */
    WorkerMessage createWorkerMessageFromPerWorkerMetrics(PerWorkerMetrics metrics);
  
    /**
     * Reports the worker messages to dataflow. We currently report autoscaling signals and
     * perworkermetrics with this path.
     *
     * @param msg the WorkerMessages to report
     * @return a list of {@link WorkerMessageResponse}
     */
    List<WorkerMessageResponse> reportWorkerMessage(List<WorkerMessage> messages) throws IOException;
  }
  