| /** |
| * 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. |
| */ |
| package org.apache.hadoop.hdfs.server.namenode; |
| |
| import java.util.Collection; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| |
| /** |
| * Given a set of checkable resources, this class is capable of determining |
| * whether sufficient resources are available for the NN to continue operating. |
| */ |
| @InterfaceAudience.Private |
| final class NameNodeResourcePolicy { |
| |
| /** |
| * Return true if and only if there are sufficient NN |
| * resources to continue logging edits. |
| * |
| * @param resources the collection of resources to check. |
| * @param minimumRedundantResources the minimum number of redundant resources |
| * required to continue operation. |
| * @return true if and only if there are sufficient NN resources to |
| * continue logging edits. |
| */ |
| static boolean areResourcesAvailable( |
| Collection<? extends CheckableNameNodeResource> resources, |
| int minimumRedundantResources) { |
| |
| // TODO: workaround: |
| // - during startup, if there are no edits dirs on disk, then there is |
| // a call to areResourcesAvailable() with no dirs at all, which was |
| // previously causing the NN to enter safemode |
| if (resources.isEmpty()) { |
| return true; |
| } |
| |
| int requiredResourceCount = 0; |
| int redundantResourceCount = 0; |
| int disabledRedundantResourceCount = 0; |
| for (CheckableNameNodeResource resource : resources) { |
| if (!resource.isRequired()) { |
| redundantResourceCount++; |
| if (!resource.isResourceAvailable()) { |
| disabledRedundantResourceCount++; |
| } |
| } else { |
| requiredResourceCount++; |
| if (!resource.isResourceAvailable()) { |
| // Short circuit - a required resource is not available. |
| return false; |
| } |
| } |
| } |
| |
| if (redundantResourceCount == 0) { |
| // If there are no redundant resources, return true if there are any |
| // required resources available. |
| return requiredResourceCount > 0; |
| } else { |
| return redundantResourceCount - disabledRedundantResourceCount >= |
| minimumRedundantResources; |
| } |
| } |
| } |