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From "Kay Kay (JIRA)" <j...@apache.org>
Subject [jira] Commented: (SOLR-912) org.apache.solr.common.util.NamedList - Typesafe efficient variant - ModernNamedList introduced - implementing the same API as NamedList
Date Fri, 19 Dec 2008 16:27:44 GMT

    [ https://issues.apache.org/jira/browse/SOLR-912?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12658114#action_12658114
] 

Kay Kay commented on SOLR-912:
------------------------------

System.arrayCopy is great. It is bound to perform much better because of the native code for
the same. 

Meanwhile - w.r.t resize() - ( trade-off because increasing size a lot would increase memory
usage.  increase a size by a smaller factor would be resulting in a more frequent increases
in size). I believe reading some theory that the ideal increase factor is somewhere close
to  ( 1 + 2^0.5) / 2  or something similar to that. 


The method - ensureCapacity(capacity) in ArrayList (Java 6) also seems to be a number along
the lines ~ (1.5)

	    int newCapacity = (oldCapacity * 3)/2 + 1; 

+1 seems to be move away from 0, and keep incrementing the count. ( Hmm .. That piece of code
- in Java 6 ArrayList can definitely make use of bitwise operators for the div-by-2 operation
!!).



> 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
>
>   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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