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https://issues.apache.org/jira/browse/PIVOT-198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12743193#action_12743193
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Greg Brown commented on PIVOT-198:
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I just ran a test to see what kind of numbers we are looking at here. For sure,
updating individual path elements is faster. However, the gain would be
unnoticeable to most users.
For 1,000 simulated selected paths, in the worst-case scenario of updating all
of them, the numbers were as follows (averaged over 10,000 test runs):
Update: 0.0342ms; new: 0.2818ms
So, updating 1,000 paths took 0.03ms, whereas replacing them took 0.28ms.
Neither one is going to be noticeable to the user, and 1,000 items is a pretty
extreme case. Also, this performance hit is only incurred when tree data is
actually modified when a large number of items are selected - this isn't a
situation we're likely to run into very often.
On the other hand, asking for a tree view's current selection may happen fairly
often. Here's the results of copying the entire path structure vs. returning an
immutable list:
Copy: 0.2521ms; get: 0.0008ms
Either way you look at it, the numbers are negligible. However, since the
performance penalty of updating the selection is only paid when the model
changes under an existing selection, and callers may often be asking for the
current selection state, I would suggest that using immutable paths is the
better alternative.
> Create ImmutablePath class; update TreeView to use ImmutableList in
> getSelectedPaths()
> --------------------------------------------------------------------------------------
>
> Key: PIVOT-198
> URL: https://issues.apache.org/jira/browse/PIVOT-198
> Project: Pivot
> Issue Type: Improvement
> Components: wtk
> Affects Versions: 1.3
> Reporter: Greg Brown
> Assignee: Todd Volkert
> Priority: Minor
> Fix For: 1.3
>
>
> Create an ImmutablePath class that extends Path; use these internally in
> TreeView so we can return an ImmutableList wrapper around the selected paths
> and avoid the deep copy that we currently perform.
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