RFR: 8264048: Fix caching in Jar URL connections when an entry is missing

[Aleksei Efimov]

On Wed, 31 Mar 2021 11:24:02 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Current fix tries to tackle an issue with URL connection referencing non-existing Jar file entries:
>> If an entry that doesn't exist is specified in an URL connection the underlying Jar file is still cached even if an exception is thrown after that. Such behavior prevents the caller, for instance, a `URLClassLoader`, from closing a Jar file.
>> 
>> The proposed fix checks if entry exists before caching a Jar file (only for cases with enabled caching):
>> - If entry exists - jar file is cached if it wasn't cached before
>> - If entry doesn't exist and jar file wasn't cached before - jar file is closed and exception is thrown
>> - If entry doesn't exist and jar file was cached before - jar file is kept cached and exception is thrown
>> 
>> 
>> The following tests have been used to verify the fix:
>> - New regression tests
>> - ``:jdk_core:`` tests
>> - `api/java_util`,`api/java_net` JCK tests
>
> Hi Aleksei, thanks for putting this together.
> 
> `test/jdk/sun/misc/URLClassPath/RemoveJar.java` seems to be an older version of `test/jdk/java/net/URLClassLoader/RemoveJar.java`. The two tests are almost identical - so `test/jdk/sun/misc/URLClassPath/RemoveJar.java` can probably be removed from the PR.
> 
> Otherwise the proposed changes look good to me.

Thanks for the review, Daniel. It is correct that `test/jdk/sun/misc/URLClassPath/RemoveJar.java` is an old version. It is removed now.

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PR: https://git.openjdk.java.net/jdk/pull/3263