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