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https://issues.apache.org/jira/browse/HBASE-18555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16123212#comment-16123212
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Xiang Li commented on HBASE-18555:
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Hi Mike,
Regarding
bq. Your modification to getCellList makes it look almost identical to the
get/null-check/put pattern though. What am I missing?
yes, the patch updates the logic of Mutation#getCellList(family) to be
get/null-check/put pattern.
Please allow me to summarize the code path in different scenarios
* Without the patch
** When cell list for a family exists: get list from map -> null check ->
update list -> {color:#d04437}put list to map (could be removed){color}
** When cell list for a family does not exist: get list from map -> null check
-> allocate list -> {color:#59afe1}update list -> put list to map{color}
* With the patch
** When cell list for a family exists: {color:#14892c}get list from map -> null
check -> update list {color}
** When cell list for a family does not exist: get list from map -> null check
-> allocate list -> {color:#59afe1}put list to map -> update list{color}
The patch targets to remove the redundant Map#put() when cell list for a family
already exists (remove the red to make it as green)
It also changes the logic when the cell list for a family does not exit, by
moving Map#put() to be in front of List#add(), in blue, but does not do any
harm.
> 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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