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https://issues.apache.org/jira/browse/LUCENE-9281?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Uwe Schindler updated LUCENE-9281:
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Description:
We currently have our own implementation of the service loader standard (SPI)
fo several reasons:
(1) In some older JDKs the order of classpath was not respected and this lead
to wrong order of codecs implementing the same SPI name. This caused tests to
sometimes use wrong class (we had this in Lucene 4 where we had a test-only
read/write Lucene3 codec that was listed before the read-only one). That's no
longer an issue, the order of loading does not matter. In addition, Java now
does everything correct.
(2) In Analysis, we require SPI classes to have a constructor taking args (a
Map of params in our case). We also extract the NAME from a static field.
Standard service loader does not support this, it tries to instantiate the
class with default ctor.
With Java 9+, the ServiceLoader now has a stream() method that allows to filter
and preprocess classes:
https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/ServiceLoader.html#stream()
This allows us to use the new interface and just get the loaded class (which
may come from module-info.class or a conventional SPI file):
https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/ServiceLoader.Provider.html#type()
This change allows us to convert Lucene to modules listing all SPIs in the
module-info.java.
was:
We currently have our own implementation of the service loader standard (SPI)
fo several reasons:
(1) In some older JDKs the order of classpath was not respected and this lead
to wrong order of codecs implementing the same SPI name. This caused tests to
sometimes use wrong class (we had this in Lucene 4 where we had a test-only
read/write Lucene3 codec that was listed before the read-only one). That's no
longer an issue, the order of loading does not matter. In addition, Java now
does everything correct.
(2) In Analysis, we require SPI classes to have a constructor taking ARGS.
standard service loader does not support this. With Java 9+, the ServiceLoader
now has a stream() method that allows to filter and preprocess classes:
https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/ServiceLoader.html#stream()
This allows us to use the new interface and just get the loaded class (which
may come from module-info.class or a conventional SPI file):
https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/ServiceLoader.Provider.html#type()
This change allows us to convert Lucene to modules listing all SPIs in the
module-info.java.
> Retire SPIServiceIterator from master because Java 9+ uses different
> mechanism to load services when module system is used
> --------------------------------------------------------------------------------------------------------------------------
>
> Key: LUCENE-9281
> URL: https://issues.apache.org/jira/browse/LUCENE-9281
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/other
> Affects Versions: master (9.0)
> Reporter: Uwe Schindler
> Assignee: Uwe Schindler
> Priority: Major
>
> We currently have our own implementation of the service loader standard (SPI)
> fo several reasons:
> (1) In some older JDKs the order of classpath was not respected and this lead
> to wrong order of codecs implementing the same SPI name. This caused tests to
> sometimes use wrong class (we had this in Lucene 4 where we had a test-only
> read/write Lucene3 codec that was listed before the read-only one). That's no
> longer an issue, the order of loading does not matter. In addition, Java now
> does everything correct.
> (2) In Analysis, we require SPI classes to have a constructor taking args (a
> Map of params in our case). We also extract the NAME from a static field.
> Standard service loader does not support this, it tries to instantiate the
> class with default ctor.
> With Java 9+, the ServiceLoader now has a stream() method that allows to
> filter and preprocess classes:
> https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/ServiceLoader.html#stream()
> This allows us to use the new interface and just get the loaded class (which
> may come from module-info.class or a conventional SPI file):
> https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/ServiceLoader.Provider.html#type()
> This change allows us to convert Lucene to modules listing all SPIs in the
> module-info.java.
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