| /* |
| * 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.auto.service.AutoService; |
| import java.io.Closeable; |
| import java.util.ServiceLoader; |
| import org.apache.beam.runners.core.metrics.ExecutionStateTracker; |
| import org.apache.beam.sdk.annotations.Experimental; |
| |
| /** |
| * A {@link ContextActivationObserver} provides a contract to register objects with the |
| * DataflowExecutionContext. |
| * |
| * <p>All methods of a {@link ContextActivationObserver} are required to be thread safe. |
| */ |
| public interface ContextActivationObserver extends Closeable { |
| /** |
| * Returns a {@link Closeable} based on the given {@link ExecutionStateTracker}. The closeable |
| * will be invoked when the {@link DataflowExecutionContext} is deactivated. |
| */ |
| public Closeable activate(ExecutionStateTracker executionStateTracker); |
| |
| /** |
| * {@link ContextActivationObserver}s can be automatically registered with this SDK by creating a |
| * {@link ServiceLoader} entry and a concrete implementation of this interface. |
| * |
| * <p>It is optional but recommended to use one of the many build time tools such as {@link |
| * AutoService} to generate the necessary META-INF files automatically. |
| */ |
| @Experimental |
| public interface Registrar { |
| /** |
| * Returns a boolean indicating whether DataflowExecutionContext should register this observer |
| * or not. |
| */ |
| boolean isEnabled(); |
| |
| /** |
| * Returns a {@link ContextActivationObserver} which will be registered by default within each |
| * {@link ContextActivationObserverRegistry registry} instance. |
| */ |
| ContextActivationObserver getContextActivationObserver(); |
| } |
| } |