[
https://issues.apache.org/jira/browse/LUCENE-2355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12853244#action_12853244
]
Earwin Burrfoot commented on LUCENE-2355:
-----------------------------------------
- DR.clone() doesn't do ensureOpen(), you can successfully clone a DR over
empty index, or get weird exception from underlying SR on non-empty index. If
you relax synchronized blocks guarding clone/reopen for readonly readers (which
is okay, in theory), it gets even more fun, as no checks are done when
incRefing SR.CoreReaders.
I think I'm going to introduce interface RefCounted, abstract class
WhateverRefCounted, which guards against increment on closed instance and has
nice mass-decRef methods in IOUtils.
> Refactor Directory/Multi/SegmentReader creation/reopening/cloning/closing
> -------------------------------------------------------------------------
>
> Key: LUCENE-2355
> URL: https://issues.apache.org/jira/browse/LUCENE-2355
> Project: Lucene - Java
> Issue Type: Improvement
> Reporter: Earwin Burrfoot
>
> *Reader lifecycle evolved over time to become some heavily tangled mess. It's
> hard to understand what's going on there, it's even harder to add some
> fields/logic while ensuring that all possible code paths preserve these
> fields/interact with the logic properly. While some of said mess is justified
> by the task at hand, a big part is just badly done copypaste and can be
> removed.
> I am currently refactoring this and intended to open an issue with a working
> patch, but the task winded up somewhat bigger than I expected, so I'm opening
> it earlier to track stuff encountered/changed/fixed.
> The list is by no means exhaustive.
> - an iteration to create SRs is copypasted several times, one of them (IW)
> with wrong iteration bound
> - it is also overly complex and can be folded for create/reopen cases
> - readers sent to IndexReaderWarmer are termindexless/docstoreless on some
> occasions
> - it is possible to clone() your way to readwrite NRT reader
> - IndexDeletionPolicy is not always preserved through clones/reopens
> - cloned readers share CoreReaders and, consequently, updated
> termsIndex/docStores
> - threadlocal versions of fieldsReader/termsVector are bound to SR, not
> CoreReaders and thus are recreated on clone/reopen
> - double-initialization for some fields (someone got lost and did this to be
> sure I guess), stupid assert checks ( qwe = new(); assert qwe != null )
> - SR is not always recreated when compound status of underlying segment
> changes
> - deleting already deleted doc marks deletions dirty and rewrites them
> - lots of synchronization is done around Reader, while it can be narrowed
> down to norms/deletions/whatever
> I did some structural modifications:
> - CompositeReader extracts common code from DirectoryReader and MultiReader
> (complete)
> - ReadonlyDirectoryReader and ReadonlySegmentReader are dead,
> MutableD/SReaders are introduced and carry all modification logic/fields (DR
> complete, SR in progress)
> - WriterBackedReader encapsulates NRT reader logic (complete)
> - CoreReaders split into CoreReaders, DocStores, TermInfos. All of these are
> immutable and SR is cloned when you need to change its mode (in progress)
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
---------------------------------------------------------------------
To unsubscribe, e-mail: java-dev-unsubscr...@lucene.apache.org
For additional commands, e-mail: java-dev-h...@lucene.apache.org
