hadoop FSImageStorageInspector 源码
haddop FSImageStorageInspector 代码
文件路径：/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageStorageInspector.java
/**
* 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.io.File;
import java.io.IOException;
import java.util.List;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
/**
* Interface responsible for inspecting a set of storage directories and devising
* a plan to load the namespace from them.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
abstract class FSImageStorageInspector {
/**
* Inspect the contents of the given storage directory.
*/
abstract void inspectDirectory(StorageDirectory sd) throws IOException;
/**
* @return false if any of the storage directories have an unfinalized upgrade
*/
abstract boolean isUpgradeFinalized();
/**
* Get the image files which should be loaded into the filesystem.
* @throws IOException if not enough files are available (eg no image found in any directory)
*/
abstract List<FSImageFile> getLatestImages() throws IOException;
/**
* Get the minimum tx id which should be loaded with this set of images.
*/
abstract long getMaxSeenTxId();
/**
* @return true if the directories are in such a state that the image should be re-saved
* following the load
*/
abstract boolean needToSave();
/**
* Record of an image that has been located and had its filename parsed.
*/
static class FSImageFile {
final StorageDirectory sd;
final long txId;
private final File file;
FSImageFile(StorageDirectory sd, File file, long txId) {
assert txId >= 0 || txId == HdfsServerConstants.INVALID_TXID
: "Invalid txid on " + file +": " + txId;
this.sd = sd;
this.txId = txId;
this.file = file;
}
File getFile() {
return file;
}
public long getCheckpointTxId() {
return txId;
}
@Override
public String toString() {
return String.format("FSImageFile(file=%s, cpktTxId=%019d)",
file.toString(), txId);
}
}
}
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