[HBASE-23102] Improper Usage of Map putIfAbsent

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.3.0
• Fix Version/s: 3.0.0-alpha-1, 2.6.0, 2.5.4
• Labels: newbie noob
• Assignee: David Mollitor
• Reporter: David Mollitor
• Created: 01/Oct/19 13:03
• Updated: 02/Mar/23 19:56
• Resolved: 01/Mar/23 14:00

Description

When using Map#putIfAbsent, the argument should not be a new object. Otherwise, if the item is present, the object that was instantiated is immediately thrown away. Instead, use Map#computeIfAbsent so that the object is only instantiated if it is needed.

There exists a good example in the Map JavaDoc:

https://docs.oracle.com/javase/8/docs/api/java/util/Map.html#computeIfAbsent-K-java.util.function.Function-

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Locations

https://github.com/apache/hbase/blob/9370347efea5b09e2fa8f4e5d82fa32491e1181b/hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/QuotaCache.java#L227-L236

https://github.com/apache/hbase/blob/025ddce868eb06b4072b5152c5ffae5a01e7ae30/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/throttle/StoreHotnessProtector.java#L124-L129

https://github.com/apache/hbase/blob/1170f28122d9d36e511ba504a5263ec62e11ef6a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStates.java#L555

https://github.com/apache/hbase/blob/4ca760fe9dd373b8d8a4c48db15e42424920653c/hbase-rsgroup/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupAdminServer.java#L584-L586

https://github.com/apache/hbase/blob/4ca760fe9dd373b8d8a4c48db15e42424920653c/hbase-rsgroup/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupAdminServer.java#L585

https://github.com/apache/hbase/blob/5b01e613fbbb92e243e99a1d199b4ffbb21ed2d9/hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/ProcedureExecutor.java#L834

Issue Links

• is depended upon by: HBASE-27250 MasterRpcService#setRegionStateInMeta does not support replica region encodedNames or region names
• links to: GitHub Pull Request #828
• links to: GitHub Pull Request #5048
• links to: GitHub Pull Request #5062