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From "Mark Miller (JIRA)" <j...@apache.org>
Subject [jira] Updated: (LUCENE-831) Complete overhaul of FieldCache API/Implementation
Date Wed, 15 Apr 2009 22:47:15 GMT

     [ https://issues.apache.org/jira/browse/LUCENE-831?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mark Miller updated LUCENE-831:
-------------------------------

    Attachment: LUCENE-831.patch

I've added your SortField constructor Uwe.

I've also switched things to what I proposed.

You can access a ValueSource from SegmentReaders with getValueSource. You get a USO Exception
on non SegmentReaders with the hint to use getSequentialSubReaders.
The built in FieldCache usage uses this new API instead, allowing caching per segment without
global caching keyed by IndexReader. Its hardwired at the moment, but you would be able to
set it on IndexReader open.

There is a back compat CacheByReaderUninverterValueSource that caches in a WeakHashMap by
IndexReader and Uninverter (Uninverter is actually keyed by the Parser it wraps). This
works as a Singleton. Deprecated code, like the FieldCache uses this. You wouldn't want to
straddle both API's, because for identical types / uninversion you would duplicate data (eg
if you asked both APIs for the same data type with
the same parser/uninverter and field, you would get twice the data in RAM). This method still
works with MultiReaders, and so nicely solves back compat with regards to only allowing access
to ValueSource from the SegmentReader.

You can also set a ValueSource on a SortField. This would override the ValueSource used at
sort time to one provided. There is a convenience class called CacheByReaderValueSource that
caches
by Reader, field, type, key.

I think that solves all three needs (and my caching concerns) in a pretty nice way. Patch
is not done, but all tests now pass except for TrieRange (have not run back compat tests yet
due to Trie failure - havnt looked into yet either).

> Complete overhaul of FieldCache API/Implementation
> --------------------------------------------------
>
>                 Key: LUCENE-831
>                 URL: https://issues.apache.org/jira/browse/LUCENE-831
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>            Reporter: Hoss Man
>            Assignee: Mark Miller
>             Fix For: 3.0
>
>         Attachments: ExtendedDocument.java, fieldcache-overhaul.032208.diff, fieldcache-overhaul.diff,
fieldcache-overhaul.diff, LUCENE-831-trieimpl.patch, LUCENE-831.03.28.2008.diff, LUCENE-831.03.30.2008.diff,
LUCENE-831.03.31.2008.diff, LUCENE-831.patch, LUCENE-831.patch, LUCENE-831.patch, LUCENE-831.patch,
LUCENE-831.patch, LUCENE-831.patch, LUCENE-831.patch, LUCENE-831.patch, LUCENE-831.patch,
LUCENE-831.patch, LUCENE-831.patch, LUCENE-831.patch, LUCENE-831.patch
>
>
> Motivation:
> 1) Complete overhaul the API/implementation of "FieldCache" type things...
>     a) eliminate global static map keyed on IndexReader (thus
>         eliminating synch block between completley independent IndexReaders)
>     b) allow more customization of cache management (ie: use 
>         expiration/replacement strategies, disk backed caches, etc)
>     c) allow people to define custom cache data logic (ie: custom
>         parsers, complex datatypes, etc... anything tied to a reader)
>     d) allow people to inspect what's in a cache (list of CacheKeys) for
>         an IndexReader so a new IndexReader can be likewise warmed. 
>     e) Lend support for smarter cache management if/when
>         IndexReader.reopen is added (merging of cached data from subReaders).
> 2) Provide backwards compatibility to support existing FieldCache API with
>     the new implementation, so there is no redundent caching as client code
>     migrades to new API.

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