org.apache.hadoop.hdfs.server.diskbalancer.planner.package-info Maven / Gradle / Ivy
/**
* 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.
*/
/**
* Planner takes a DiskBalancerVolumeSet, threshold and
* computes a series of steps that lead to an even data
* distribution between volumes of this DiskBalancerVolumeSet.
*
* The main classes of this package are steps and planner.
*
* Here is a high level view of how planner operates:
*
* DiskBalancerVolumeSet current = volumeSet;
*
* while(current.isBalancingNeeded(thresholdValue)) {
*
* // Creates a plan , like move 20 GB data from v1 {@literal ->} v2
* Step step = planner.plan(current, thresholdValue);
*
* // we add that to our plan
* planner.addStep(current, step);
*
* // Apply the step to current state of the diskSet to
* //compute the next state
* current = planner.apply(current, step);
* }
*
* //when we are done , return the list of steps
* return planner;
*/
package org.apache.hadoop.hdfs.server.diskbalancer.planner;