RFR: 8281335: Allow a library already loaded via System::loadLibrary to be loaded as a raw library [v3]

[Mandy Chung]

On Tue, 15 Feb 2022 09:48:21 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Mandy Chung has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove the coupling of RawNativeLibraries with JNI library loading
>
> src/java.base/share/classes/jdk/internal/loader/NativeLibraries.java line 427:
> 
>> 425:             new ConcurrentHashMap<>();
>> 426: 
>> 427:     static void acquireNativeLibraryLock(String libraryName) {
> 
> Note sure about these two routines. Should they be shared? Should we have two locks, one for JNI, one for raw? Of course, as is the code looks fine - but I wonder if a single lock isn't overly strict.

I initially planned to come back to this but I obviously forgot.  

This does not need the per-library locking for JNI library which avoids the deadlock due to the class and library loading scenarios involving JNI_OnLoad, class initialization, and `Sytem::loadLibrary`.   I now removed the locking entirely as it uses the concurrent hash map to register/unregister the loaded libraries.  Much simplified.

> src/java.base/share/classes/jdk/internal/loader/RawNativeLibraries.java line 107:
> 
>> 105:      * {@link System#mapLibraryName} can be used to convert a name to
>> 106:      * a platform-specific pathname:
>> 107:      * {@snipplet
> 
> Suggestion:
> 
>      * {@snippet

Fixed.

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PR: https://git.openjdk.java.net/jdk/pull/7435