RFR: 8292375: Convert ProtectionDomainCacheTable to ResourceHashtable [v7]

[David Holmes]

On Thu, 1 Sep 2022 12:29:41 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Since I know what this table does, either comment is fine if it helps someone understand it.
>> The "map each PD to itself" is pretty odd to me too.   How about collect each PD for fast lookup in a hashtable?  The code says how it's mapped.  There isn't that much code and it's easy to see how the Key is mapped.
>
> // The ProtectionDomainCacheTable maps all java.security.ProtectionDomain objects that are
> // registered by DictionaryEntry::add_protection_domain() to a unique entry.  The entry
> // is a WeakHandle that holds the protection domain oop.
> 
> or points to....  either is accurate.

It is the "maps ... to a unique entry" that I find most problematic - it begs the question as to what the unique entry is, when in reality it maps a PD instance (wrapped in a WeakHandle) to itself (wrapped in a WeakHandle).

For the sake of progress, approved.

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PR: https://git.openjdk.org/jdk/pull/10043