ml.shifu.guagua.master.MasterInterceptor Maven / Gradle / Ivy
/*
* Copyright [2013-2014] PayPal Software Foundation
*
* Licensed 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 ml.shifu.guagua.master;
import ml.shifu.guagua.io.Bytable;
/**
* {@link MasterInterceptor} defines hook points for each guagua application. Four hooks are defined like hooks before
* and after application and hooks after and before each iteration.
*
*
* Almost all services in guagua like coordination, fail-over, profiler are implemented as interceptors. These are
* system interceptors can be configured by using command line '-D' parameter.
*
*
* After system interceptors, user defined interceptors are also supported for user to define his/her own interceptors.
* Check SumOutput in examples project to see how interceper is used to save global result at the end of
* one guagua application.
*
*
* For a list of interceptors, the order to call preXXX methods and postXXX methods is different. For example, a and b
* two interceptors. The order is
* a.preApplication->b.preApplication->a.preIteration->b.preIteration->computation->b.postIteration
* ->a.postIteration->b.postApplication->a.postApplication. This is like call stack to make sure each
* interceptor to intercept the whole other interceptors and master computation.
*
*
* {@link BasicMasterInterceptor} is a empty implementation for user to choose the hooks to override.
*
* @param
* master computation result in each iteration.
* @param
* worker computation result in each iteration.
* @see BasicMasterInterceptor
*/
public interface MasterInterceptor {
/**
* The hook point before any computation logic.
*
* @param context
* the master context instance which includes worker results and other useful parameters.
*/
void preApplication(MasterContext context);
/**
* The hook point before computation of each iteration.
*
* @param context
* the master context instance which includes worker results and other useful parameters.
*/
void preIteration(MasterContext context);
/**
* The hook point after computation of each iteration.
*
* @param context
* the master context instance which includes worker results and other useful parameters.
*/
void postIteration(MasterContext context);
/**
* The hook point after any computation logic.
*
* @param context
* the master context instance which includes worker results and other useful parameters.
*/
void postApplication(MasterContext context);
}