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https://issues.apache.org/jira/browse/HDFS-11114?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15645304#comment-15645304
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ASF GitHub Bot commented on HDFS-11114:
---------------------------------------
Github user anuengineer commented on a diff in the pull request:
https://github.com/apache/hadoop/pull/153#discussion_r86860005
--- Diff:
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/checker/AsyncChecker.java
---
@@ -0,0 +1,62 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.datanode.checker;
+
+import com.google.common.util.concurrent.ListenableFuture;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * A class that can be used to schedule an asynchronous check on a given
+ * {@link Checkable}. If the check is successfully scheduled then a
+ * {@link ListenableFuture} is returned.
+ *
+ */
[email protected]
[email protected]
+public interface AsyncChecker<K, V> {
+
+ /**
+ * Schedule an asynchronous check for the given object.
+ *
+ * @param target object to be checked.
+ *
+ * @param context the interpretation of the context depends on the
+ * target.
+ *
+ * @return returns a {@link ListenableFuture} that can be used to
+ * retrieve the result of the asynchronous check.
+ */
+ ListenableFuture<V> schedule(Checkable<K, V> target, K context);
+
+ /**
+ * Cancel all executing checks and wait for them to complete.
+ * First attempts a graceful cancellation, then cancels forcefully.
+ * Waits for the supplied timeout after both attempts.
+ *
+ * See {@link ExecutorService#awaitTermination} for a description of
+ * the parameters.
+ *
+ * @throws InterruptedException
+ */
+ void join(long timeout, TimeUnit timeUnit) throws InterruptedException;
--- End diff --
Just trying to understand this a little better, From the signature and
implementation this function looks more a awaitTermination in executorService.
That is this function will wait for a while and cancel and task if the timeout
occurs, in that case would you consider calling this await or awaitTermination.
Java "join" seems to imply a wait without timeouts. Just making sure that the
intended was indeed a shutdown/await pattern.
> Support for running async disk checks in DataNode
> -------------------------------------------------
>
> Key: HDFS-11114
> URL: https://issues.apache.org/jira/browse/HDFS-11114
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode
> Reporter: Arpit Agarwal
> Assignee: Arpit Agarwal
> Attachments: HDFS-11114.01.patch, HDFS-11114.02.patch
>
>
> Introduce support for running async checks.
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