Upgradeable.java
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上传日期:2018-01-08
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- /**
- * 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.common;
- import java.io.IOException;
- import org.apache.hadoop.hdfs.server.protocol.UpgradeCommand;
- /**
- * Common interface for distributed upgrade objects.
- *
- * Each upgrade object corresponds to a layout version,
- * which is the latest version that should be upgraded using this object.
- * That is all components whose layout version is greater or equal to the
- * one returned by {@link #getVersion()} must be upgraded with this object.
- */
- public interface Upgradeable extends Comparable<Upgradeable> {
- /**
- * Get the layout version of the upgrade object.
- * @return layout version
- */
- int getVersion();
- /**
- * Get the type of the software component, which this object is upgrading.
- * @return type
- */
- HdfsConstants.NodeType getType();
- /**
- * Description of the upgrade object for displaying.
- * @return description
- */
- String getDescription();
- /**
- * Upgrade status determines a percentage of the work done out of the total
- * amount required by the upgrade.
- *
- * 100% means that the upgrade is completed.
- * Any value < 100 means it is not complete.
- *
- * The return value should provide at least 2 values, e.g. 0 and 100.
- * @return integer value in the range [0, 100].
- */
- short getUpgradeStatus();
- /**
- * Prepare for the upgrade.
- * E.g. initialize upgrade data structures and set status to 0.
- *
- * Returns an upgrade command that is used for broadcasting to other cluster
- * components.
- * E.g. name-node informs data-nodes that they must perform a distributed upgrade.
- *
- * @return an UpgradeCommand for broadcasting.
- * @throws IOException
- */
- UpgradeCommand startUpgrade() throws IOException;
- /**
- * Complete upgrade.
- * E.g. cleanup upgrade data structures or write metadata to disk.
- *
- * Returns an upgrade command that is used for broadcasting to other cluster
- * components.
- * E.g. data-nodes inform the name-node that they completed the upgrade
- * while other data-nodes are still upgrading.
- *
- * @throws IOException
- */
- UpgradeCommand completeUpgrade() throws IOException;
- /**
- * Get status report for the upgrade.
- *
- * @param details true if upgradeStatus details need to be included,
- * false otherwise
- * @return {@link UpgradeStatusReport}
- * @throws IOException
- */
- UpgradeStatusReport getUpgradeStatusReport(boolean details) throws IOException;
- }