| Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
| Stage |
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| 1.0;1 |
| 1 | /* | |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one or more | |
| 3 | * contributor license agreements. See the NOTICE file distributed with | |
| 4 | * this work for additional information regarding copyright ownership. | |
| 5 | * The ASF licenses this file to You under the Apache License, Version 2.0 | |
| 6 | * (the "License"); you may not use this file except in compliance with | |
| 7 | * the License. You may obtain a copy of the License at | |
| 8 | * | |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 | |
| 10 | * | |
| 11 | * Unless required by applicable law or agreed to in writing, software | |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, | |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| 14 | * See the License for the specific language governing permissions and | |
| 15 | * limitations under the License. | |
| 16 | */ | |
| 17 | ||
| 18 | package org.apache.commons.pipeline; | |
| 19 | ||
| 20 | /** | |
| 21 | * <p>A Stage represents a set of tasks that can be performed on objects | |
| 22 | * in a queue, and methods used to communicate with other stages | |
| 23 | * in a {@link Pipeline}.</p> | |
| 24 | */ | |
| 25 | public interface Stage { | |
| 26 | ||
| 27 | /** | |
| 28 | * <p>Initialization takes place when the stage is added to a pipeline. | |
| 29 | * Implementations of this method should perform any necessary setup that | |
| 30 | * is required for the driver to be able to correctly run the stage.</p> | |
| 31 | * <p><strong>NOTE:</strong> Since this method is run when the stage is | |
| 32 | * added to the pipeline, certain information (such as the downstream | |
| 33 | * feeder for the stage) may not yet be available until the pipeline is | |
| 34 | * fully constructoed.</p> | |
| 35 | * @param context the {@link StageContext} within which the stage sill be run | |
| 36 | */ | |
| 37 | public void init(StageContext context); | |
| 38 | ||
| 39 | /** | |
| 40 | * Implementations of this method should perform any necessary setup that | |
| 41 | * needs to be done before any data is processed. | |
| 42 | * Preprocessing is performed after initialization. | |
| 43 | * | |
| 44 | * @throws StageException any checked Exception thrown by the implementation should | |
| 45 | * be wrapped in a {@link StageException} | |
| 46 | */ | |
| 47 | public void preprocess() throws StageException; | |
| 48 | ||
| 49 | /** | |
| 50 | * Implementations of this method should atomically process a single data | |
| 51 | * object and transfer any feed objects resulting from this processing to | |
| 52 | * the downstream {@link Feeder}. This {@link Feeder} can be obtained from | |
| 53 | * the stage context made available during {@link #init initialization}. | |
| 54 | * | |
| 55 | * NOTE: Implementations of this method must be thread-safe! | |
| 56 | * | |
| 57 | * @param obj an object to be processed | |
| 58 | * @throws StageException any checked Exception thrown by the implementation should | |
| 59 | * be wrapped in a {@link StageException} | |
| 60 | */ | |
| 61 | public void process(Object obj) throws StageException; | |
| 62 | ||
| 63 | /** | |
| 64 | * Implementations of this method should do any additional processing or | |
| 65 | * finalization necessary after all data objects have been processed | |
| 66 | * by the stage. | |
| 67 | * @throws StageException any checked Exception thrown by the implementation should | |
| 68 | * be wrapped in a {@link StageException} | |
| 69 | */ | |
| 70 | public void postprocess() throws StageException; | |
| 71 | ||
| 72 | /** | |
| 73 | * Implementations of this method should clean up any lingering resources | |
| 74 | * that might otherwise be left allocated if an exception is thrown during | |
| 75 | * processing (or pre/postprocessing). | |
| 76 | */ | |
| 77 | public void release(); | |
| 78 | } |