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From "Mike Drob (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-18555) Remove redundant familyMap.put() from Put#addColumn() and addImmutable()
Date Thu, 10 Aug 2017 16:19:00 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16121851#comment-16121851
] 

Mike Drob commented on HBASE-18555:
-----------------------------------

This seems like the perfect use case for {{putIfAbsent}}

> Remove redundant familyMap.put() from Put#addColumn() and addImmutable()
> ------------------------------------------------------------------------
>
>                 Key: HBASE-18555
>                 URL: https://issues.apache.org/jira/browse/HBASE-18555
>             Project: HBase
>          Issue Type: Improvement
>          Components: Client
>            Reporter: Xiang Li
>            Assignee: Xiang Li
>            Priority: Minor
>         Attachments: HBASE-18555.master.000.patch
>
>
> In Put#addColumn() and addImmutable(), after getting the cell list of the given family
and add the cell into the list, the code puts (key=family, value=list) into familyMap.
> In addColumn(), it is like
> {code}
>     List<Cell> list = getCellList(family);
>     KeyValue kv = createPutKeyValue(family, qualifier, ts, value);
>     list.add(kv);
>     familyMap.put(CellUtil.cloneFamily(kv), list); // <-- here
>     return this;
> {code}
> In addImmutable(), it is like
> {code}
>     List<Cell> list = getCellList(family);
>     KeyValue kv = createPutKeyValue(family, qualifier, ts, value, tag);
>     list.add(kv);
>     familyMap.put(family, list); // <-- here
>     return this;
> {code}
> I think those put() for Map only take effect when getCellList(family) returns a new allocated
ArrayList. When the list for a family already exist, put() for Map will update the value to
the reference of the list, but actually, the reference of the list is not changed.
> Those put() do not do any harm in terms of the correctness when they are here. But it
could be removed to improve the performance. familyMap searches for key and set the new value
and return the old value. Those operation take some time but actually are not needed. 
> The put() could be moved into Mutation#getCellList(family)



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