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From "Michael McCandless (Updated) (JIRA)" <>
Subject [jira] [Updated] (LUCENE-3631) Remove write access from SegmentReader and possibly move to separate class or IndexWriter/BufferedDeletes/...
Date Mon, 19 Dec 2011 11:47:30 GMT


Michael McCandless updated LUCENE-3631:

    Attachment: LUCENE-3631.patch

Patch, making SegmentReader fully read-only; it's much simpler now!  I
cutover to simple ctors (3 of them, depending on how the core/del docs
are set) instead of static get methods.

I removed clone() from all IR impls and made final IR.clone() that throws
UOE.  Cloning no longer makes sense since all IRs are read-only...

I pushed all "pending deletes" tracking inside IW, and changed the
readerPool to store a map of SegmentInfo to the "state" that IW needs
to track for each segment (open reader for searching, open reader for
merging, live docs and pending delete count).

I think it's ready...

> Remove write access from SegmentReader and possibly move to separate class or IndexWriter/BufferedDeletes/...
> -------------------------------------------------------------------------------------------------------------
>                 Key: LUCENE-3631
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Task
>          Components: core/index
>    Affects Versions: 4.0
>            Reporter: Uwe Schindler
>            Assignee: Michael McCandless
>         Attachments: LUCENE-3631.patch
> After LUCENE-3606 is finished, there are some TODOs:
> SegmentReader still contains (package-private) all delete logic including crazy copyOnWrite
for validDocs Bits. It would be good, if SegmentReader itsself could be read-only like all
other IndexReaders.
> There are two possibilities to do this:
> # the simple one: Subclass SegmentReader and make a RWSegmentReader that is only used
by IndexWriter/BufferedDeletes/... DirectoryReader will only use the read-only SegmentReader.
This would move all TODOs to a separate class. It's reopen/clone method would always create
a RO-SegmentReader (for NRT).
> # Remove all write and commit stuff from SegmentReader completely and move it to IndexWriter's
readerPool (it must be in readerPool as deletions need a not-changing view on an index snapshot).
> Unfortunately the code is so complicated and I have no real experience in those internals
of IndexWriter so I did not want to do it with LUCENE-3606, I just separated the code in SegmentReader
and marked with TODO. Maybe Mike McCandless can help :-)

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