hadoop SaveNamespaceContext 源码
haddop SaveNamespaceContext 代码
文件路径：/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/SaveNamespaceContext.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.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
import org.apache.hadoop.hdfs.util.Canceler;
import org.apache.hadoop.util.Preconditions;
/**
* Context for an ongoing SaveNamespace operation. This class
* allows cancellation, and also is responsible for accumulating
* failed storage directories.
*/
@InterfaceAudience.Private
public class SaveNamespaceContext {
private final FSNamesystem sourceNamesystem;
private final long txid;
private final List<StorageDirectory> errorSDs =
Collections.synchronizedList(new ArrayList<StorageDirectory>());
private final Canceler canceller;
private final CountDownLatch completionLatch = new CountDownLatch(1);
SaveNamespaceContext(
FSNamesystem sourceNamesystem,
long txid,
Canceler canceller) {
this.sourceNamesystem = sourceNamesystem;
this.txid = txid;
this.canceller = canceller;
}
FSNamesystem getSourceNamesystem() {
return sourceNamesystem;
}
long getTxId() {
return txid;
}
void reportErrorOnStorageDirectory(StorageDirectory sd) {
errorSDs.add(sd);
}
List<StorageDirectory> getErrorSDs() {
return errorSDs;
}
void markComplete() {
Preconditions.checkState(completionLatch.getCount() == 1,
"Context already completed!");
completionLatch.countDown();
}
public void checkCancelled() throws SaveNamespaceCancelledException {
if (canceller.isCancelled()) {
throw new SaveNamespaceCancelledException(
canceller.getCancellationReason());
}
}
}
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