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https://issues.apache.org/jira/browse/GROOVY-12580?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18134520#comment-18134520
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ASF GitHub Bot commented on GROOVY-12580:
-----------------------------------------
codeconsole opened a new pull request, #3096:
URL: https://github.com/apache/groovy/pull/3096
`ClassInfo.remove(Class)` no longer takes a class's default Groovy methods
and extension methods with it. The next use of the class used to build a new
`ClassInfo` without them, so after `ClassInfo.remove(StringBuilder)` the
expression `sb << 'x'` could leave `sb` empty (it fell back to
`CharSequence.leftShift`, which returns a new builder), and after the shutdown
sweep shown in the integration guide `[1, 2, 3].collect { it * 2 }` threw
`MissingMethodException`. The class now gets its previous `ClassInfo` back
while that is still reachable, without the MetaClasses that were set for the
class or its instances, and a discarded copy of Groovy is still released.
This also makes `bugs.Groovy12363` pass when it runs after
`bugs.Groovy12142` in the same test JVM: `Groovy12142` removes
`StringBuilder`'s `ClassInfo`, and `Groovy12363` appends to a `StringBuilder`
with `<<`.
The guide's sweep is now a statically compiled method: written as dynamic
Groovy and run by the copy it cleans up, it kept that copy's class loader
reachable.
Tests: four tests in `bugs.Groovy12142` for `ClassInfo.remove` and the
documented sweep, beside a fifth that checks a discarded copy of Groovy is
still released. The `groovy`, `gls`, `bugs` and `org.codehaus.groovy` packages
pass (15,501 tests). The Checkstyle and CodeNarc gates pass. `bugs.Groovy12142`
and `bugs.Groovy12363` also pass on JDK 17.
This builds on #3095: the test of the guide's sweep needs it to pass on JDK
17.
Seen in 4.0.33, 5.0.8 and 6.0.0.
> ClassInfo.remove takes a class's default Groovy methods with it
> ---------------------------------------------------------------
>
> Key: GROOVY-12580
> URL: https://issues.apache.org/jira/browse/GROOVY-12580
> Project: Groovy
> Issue Type: Bug
> Components: groovy-runtime
> Affects Versions: 4.0.33, 5.0.8, 6.0.0
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> {{ClassInfo.remove(Class)}} drops the class's association, and the next use
> of the class creates a new {{ClassInfo}}. The default Groovy methods and
> extension methods of a class are written into its {{ClassInfo}} once, by the
> registry at startup, so the class loses them for the rest of the runtime's
> life:
> {code:groovy}
> import org.codehaus.groovy.reflection.ClassInfo
> ClassInfo.remove(StringBuilder)
> def sb = new StringBuilder('ab')
> sb[0..0] = 'z' // MissingMethodException: No signature of method: putAt for
> class: java.lang.StringBuilder
> {code}
> {{sb << 'x'}} falls back to {{CharSequence.leftShift}}, which returns a new
> builder and leaves {{sb}} empty, or to {{Appendable.leftShift}}, depending on
> hash order. After the sweep the integration guide documents for application
> shutdown, a runtime still in use loses every default Groovy method:
> {code:groovy}
> import org.codehaus.groovy.reflection.ClassInfo
> for (ClassInfo ci : ClassInfo.getAllClassInfo()) { Class<?> c =
> ci.getTheClass(); if (c != null) ClassInfo.remove(c) }
> [1, 2, 3].collect { it * 2 } // MissingMethodException: No signature of
> method: multiply for class: java.lang.Integer
> {code}
> {{bugs.Groovy12142.testClassInfoRemoveSweepIsSafeToRunRepeatedly}} removes
> the {{ClassInfo}} of {{StringBuilder}}, so {{bugs.Groovy12363}}, whose
> anonymous class does {{sink << who}}, fails when it runs later in the same
> test JVM.
> The guide's sweep, written as dynamic Groovy and run by the copy it cleans
> up, also keeps that copy's class loader reachable, since a dynamic call made
> after the first removal associates a class with that runtime again.
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