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https://issues.apache.org/jira/browse/SOLR-912?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12658251#action_12658251
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Kay Kay commented on SOLR-912:
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| We also need to make sure we don't eliminate any public constructors, which
seems to be the case based on my quick glance at the latest patch.
<code>
- public NamedList(List nameValuePairs) {
- nvPairs=nameValuePairs;
+ protected NamedList(List<Map.Entry<String, T>> nameValuePairs) {
+ nvPairs = nameValuePairs;
- }
</code>
As part of ensuring type-safety , the previous code had a heterogenous List
ctor. as before. I changed the access level and added another public ctor. (
Object [] ) with deprecated tag to it so that people are still able to use the
functionality.
Otherwise - retaining the same signature after type safety would imply - people
passing in a List of String-s and T-s , when the List expects Map.Entry<String
, T > and would cause more confusion.
Thanks to the erasure of generics , List and List<Map.Entry<String, T>> are all
equal , not helping here.
If backward compatibility is the key here- I can revisit the patch again
ensuring the same.
| If there are performance gains to be had in the common case i'm all for it
... but i still feel like i'm not understanding the original goal: how does
this approach give us more type safety?
When I logged the issue - type-safety was the major reason behind the same.
When I submitted by first patch and did the benchmarking - performance was also
found to be a major constraint , (with incremental addition and creation of
iterator objects). NamedList seemed to be used all over the place. As long as
we preserve the contract of the methods - this should definitely give an
additional boost - since I discovered as part of profiling of the launch of
SolrCore ( CoreContainer.Initializer.initalize() .. ) .
> org.apache.solr.common.util.NamedList - Typesafe efficient variant -
> ModernNamedList introduced - implementing the same API as NamedList
> ----------------------------------------------------------------------------------------------------------------------------------------
>
> Key: SOLR-912
> URL: https://issues.apache.org/jira/browse/SOLR-912
> Project: Solr
> Issue Type: Improvement
> Components: search
> Affects Versions: 1.4
> Environment: Tomcat 6, JRE 6, Solr 1.3+ nightlies
> Reporter: Kay Kay
> Priority: Minor
> Fix For: 1.4
>
> Attachments: NLProfile.java, SOLR-912.patch, SOLR-912.patch
>
> Original Estimate: 72h
> Remaining Estimate: 72h
>
> The implementation of NamedList - while being fast - is not necessarily
> type-safe. I have implemented an additional implementation of the same -
> ModernNamedList (a type-safe variation providing the same interface as
> NamedList) - while preserving the semantics in terms of ordering of elements
> and allowing null elements for key and values (keys are always Strings ,
> while values correspond to generics ).
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