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https://issues.apache.org/jira/browse/LUCENE-2154?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Uwe Schindler updated LUCENE-2154:
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Attachment: LUCENE-2154-Jakarta-BCEL.patch
Here the third incarnation of the patch. A little bit more complicated, because
directly assemblying bytecode, but much cleaner and without strange parsers. It
uses Jakarta BCEL, which is e.g. also used by Apache XALAN XSLTC, and its even
included in JDK5 (somehow inofficial in renamed com.sun.internal packages).
The approach is the same as with JavAssist, but has several advantages:
- The typing is hard, so all bytecode is generated using real Type classes,
retrieved from reflection analysis of the Attribute-Interface to proxy. The
method signature is copied.
- It will not likely break with later VDKs if the class format changes again.
The Problem with JavAssist is, that it loads the interface and implementation
classes from the bytecode and must analyze it. If we get Java 7 and a new
classformat, this will likely break (as e.g. classes loaded from rt.jar may not
be analyzed). The BCEL approach does not use loading classes in bytecode, it
just uses reflection to generate the proxy method signatures and inserts the
byte code to delegate to the delegate.
- The generated class is not loaded by a hack, but instead a delegating
ClassLoader is dynamically created to load the class into the JVM. The
classloader delegates all other requests to the proxied Attribute's classloader.
By the way, XALAN is bundling BCEL, in old version, but under the original
package names, which may lead to conflics when also bundling in lucene. I would
prefer to import the whole source (in parts) like automaton was put into
o.a.l.util. But that only, if we really want to do it like this way. But I
still think for some TokenStreams this would be a real speed improvement, so we
can also make a contrib package out of it.
> Need a clean way for Dir/MultiReader to "merge" the AttributeSources of the
> sub-readers
> ---------------------------------------------------------------------------------------
>
> Key: LUCENE-2154
> URL: https://issues.apache.org/jira/browse/LUCENE-2154
> Project: Lucene - Java
> Issue Type: Bug
> Components: Index
> Affects Versions: Flex Branch
> Reporter: Michael McCandless
> Fix For: Flex Branch
>
> Attachments: LUCENE-2154-cglib.patch, LUCENE-2154-Jakarta-BCEL.patch,
> LUCENE-2154-javassist.patch, LUCENE-2154-javassist.patch, LUCENE-2154.patch,
> LUCENE-2154.patch
>
>
> The flex API allows extensibility at the Fields/Terms/Docs/PositionsEnum
> levels, for a codec to set custom attrs.
> But, it's currently broken for Dir/MultiReader, which must somehow share
> attrs across all the sub-readers. Somehow we must make a single attr source,
> and tell each sub-reader's enum to use that instead of creating its own.
> Hopefully Uwe can work some magic here :)
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