001/* 002 * Copyright (c) 2016-2017 Chris K Wensel <chris@wensel.net>. All Rights Reserved. 003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved. 004 * 005 * Project and contact information: http://www.cascading.org/ 006 * 007 * This file is part of the Cascading project. 008 * 009 * Licensed under the Apache License, Version 2.0 (the "License"); 010 * you may not use this file except in compliance with the License. 011 * You may obtain a copy of the License at 012 * 013 * http://www.apache.org/licenses/LICENSE-2.0 014 * 015 * Unless required by applicable law or agreed to in writing, software 016 * distributed under the License is distributed on an "AS IS" BASIS, 017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 018 * See the License for the specific language governing permissions and 019 * limitations under the License. 020 */ 021 022package cascading.flow; 023 024import java.util.List; 025 026/** 027 * The FlowStepStrategy interface allows for on the fly customization of {@link cascading.flow.FlowStep} configuration values 028 * before they are submitted to the underlying platform. 029 * <p> 030 * Use a strategy instance to change the display name for a job, or in the case of Hadoop, the number of 031 * mapper or reducer instances. 032 * <p> 033 * Note, to change the configuration information, {@link cascading.flow.FlowStep#getConfig()} must be 034 * called to get access to the current configuration. 035 * <p> 036 * If any, the completed predecessor steps are provided so that the predecessors can be inspected via the 037 * {@link cascading.stats.FlowStepStats} interface for any information that may influence the current job. 038 * <p> 039 * It is also possible to block submission of the job by blocking in this method. 040 */ 041public interface FlowStepStrategy<Config> 042 { 043 void apply( Flow<Config> flow, List<FlowStep<Config>> predecessorSteps, FlowStep<Config> flowStep ); 044 }