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From "Uwe Schindler (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-1658) Absorb NIOFSDirectory into FSDirectory
Date Mon, 25 May 2009 13:13:45 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12712715#action_12712715
] 

Uwe Schindler commented on LUCENE-1658:
---------------------------------------

bq. In the end, I'm unsure if it's a good idea to fold anything into FSD at all. Too much
different stuff in one class becons for spahetti code  I assume your initial aim is to provide
users with best impl for current platform without making them think.

That is my problem with the whole issue, too. For me, the three directory impl are too different,
to be merged together. Especially if writing is also affected.

Using an additional parameter in the ctor specifying the type of directory is almost the same
like three classes with much cleaner code. The only thing you do not get is the automatic
directory impl choosing for filesystem dirs. But the solution to this are static factories.

bq. What about static factory that chooses between several impls? We had static factory before,
it stinked because you had to chose impl through system property, it pooled directories and
we had no public constructors. But now we have public constructors  If one needs, he uses
constructor directly. If one is lazy and wants us to choose for him he uses old API, that
simply changes semantics a bit.

That would be great. As the separate public constructors and deprecation of FSDirectory.open()
is new in 2.9, we can change it. Maybe an automatism behind open() if the System.property
is unset would be good. Advanced users may still instantiate the directories using the public
ctor.

> Absorb NIOFSDirectory into FSDirectory
> --------------------------------------
>
>                 Key: LUCENE-1658
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1658
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Store
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>            Priority: Minor
>             Fix For: 2.9
>
>         Attachments: LUCENE-1658.patch
>
>
> I think whether one uses java.io.* vs java.nio.* or eventually
> java.nio2.*, or some other means, is an under-the-hood implementation
> detail of FSDirectory and doesn't merit a whole separate class.
> I think FSDirectory should be the core class one uses when one's index
> is in the filesystem.
> So, I'd like to deprecate NIOFSDirectory, absorbing it into
> FSDirectory, and add a setting "useNIO" to FSDirectory.  It should
> default to "true" for non-Windows OSs, because it gives far better
> concurrent performance on all platforms but Windows (due to known Sun
> JRE issue http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6265734).

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