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https://issues.apache.org/jira/browse/HADOOP-19525?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17942164#comment-17942164
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ASF GitHub Bot commented on HADOOP-19525:
-----------------------------------------
YanivKunda commented on code in PR #7570:
URL: https://github.com/apache/hadoop/pull/7570#discussion_r2035164162
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/AbstractClock.java:
##########
@@ -0,0 +1,56 @@
+/**
+ * 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.util;
+
+import java.time.Clock;
+import java.time.Instant;
+import java.time.ZoneId;
+
+import static java.time.ZoneOffset.UTC;
+
+/**
+ * An abstract base class for Clocks with the following default behavior:
+ * <ul>
+ * <li>Zone-agnostic: always returns UTC, ignoring any other zones</li>
+ * <li>millis-centric: shifts responsibility of subclasses to defining {@link
#millis()},
+ * creating an Instant based on it (instead of vice versa as in {@link
java.time.Clock})</li>
+ * </ul>
+ * Subclasses that want to change this behavior can either override relevant
methods or
+ * subclass {@link java.time.Clock} directly.
+ */
+public abstract class AbstractClock extends Clock {
Review Comment:
@pan3793 thanks for the review!
This just serves as base class for `Clock`s that don't need to deal with
`ZoneId`s and mostly handle times natively via milliseconds (converting to
`Instant`s and not vice-versa).
The alternative would be to just delete it and have the two subclasses
implement this common behavior.
I can also mark it with `@LimitedPrivate` and limit it to either -
1) The only module currently using it (YARN, in ControlledClock)
2) All modules currently using `java.time.Clock` (after this change - YARN,
tools, MapReduce)
I think I prefer the first approach (delete the class) since it doesn't save
too much boilerplate anyway.
wdyt?
> Use java.time.Clock instead of org.apache.hadoop.util.Clock
> -----------------------------------------------------------
>
> Key: HADOOP-19525
> URL: https://issues.apache.org/jira/browse/HADOOP-19525
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: hadoop-common, mapreduce, yarn
> Reporter: Yaniv Kunda
> Assignee: Yaniv Kunda
> Priority: Major
> Labels: pull-request-available
>
> Hadoop's {{Clock}} interface was recently moved from
> {{org.apache.hadoop.yarn.util}} (in hadoop-yarn) to
> {{org.apache.hadoop.util}} (in hadoop-common) as part of YARN-11765.
> I propose to seize the opportunity of this being targeted done for 3.5.0 to
> modernize it usage:
> # Deprecate {{org.apache.hadoop.util.Clock}}
> # Replace all of its usages with {{java.time.Clock}}
> # Replace existing usages of its simple implementations, e.g.
> {{SystemClock}}/{{UTCClock}} with standard {{java.time.Clock}} subclasses,
> e.g. {{Clock.systemUTC()}}
> # Re-implement other implementations, e.g.
> {{MonotonicClock}}/{{ControllerClock}}, as {{java.time.Clock}} subclasses.
> The standard {{java.time.Clock}} has a richer API supports modern
> {{java.time}} classes such as {{Instant}} and {{ZoneId}}, and migration would
> be straightforward:
> Just changing {{org.apache.hadoop.util.Clock.getTime()}} to
> {{java.time.Clock.millis()}}
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