| /** |
| * 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. |
| */ |
| |
| /** |
| * This package provides a mechanism for tracking {@link NameNode} startup |
| * progress. The package models NameNode startup as a series of {@link Phase}s, |
| * with each phase further sub-divided into multiple {@link Step}s. All phases |
| * are coarse-grained and typically known in advance, implied by the structure of |
| * the NameNode codebase (example: loading fsimage). Steps are more granular and |
| * typically only known at runtime after startup begins (example: loading a |
| * specific fsimage file with a known length from a particular location). |
| * |
| * {@link StartupProgress} provides a thread-safe data structure for |
| * recording status information and counters. Various parts of the NameNode |
| * codebase use this to describe the NameNode's activities during startup. |
| * |
| * {@link StartupProgressView} provides an immutable, consistent view of the |
| * current state of NameNode startup progress. This can be used to present the |
| * data to a user. |
| * |
| * {@link StartupProgressMetrics} exposes startup progress information via JMX |
| * through the standard metrics system. |
| */ |
| @InterfaceAudience.Private |
| package org.apache.hadoop.hdfs.server.namenode.startupprogress; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.hdfs.server.namenode.NameNode; |