[crac] RFR: Introduce per-Priority Context with different policies

[Anton Kozlov]

On Thu, 18 May 2023 11:52:30 GMT, Radim Vansa <duke at openjdk.org> wrote:

>> A follow-up work for #60:
>> 
>> * Each priority now has a dedicated context, so contextes may provide different policies. CALL_SITE now uses new CriticalUnorderedContext that runs beforeCheckpoint on concurrent registration, fixes [1]. Whether or not CALL_SITE needs to be registered to at all is an open question and out of scope of this PR.
>> * the Global Context reverted from BlockingOrderedContext to OrderedContext, as that may have a huge impact on users. Probably we'll want to expose blocking/criticalUnorderd context along the global one, or at some point expose an implementation. But this is also out of scope of the PR.
>> * hierachy of the Context implementations are cleaned up a bit [2]
>> 
>> The JDKContext is now just a holder of ClaimedFDs, I'll address this in a follow-up that depends on this Context follow-up.
>> 
>> [1] https://github.com/openjdk/crac/pull/60#issuecomment-1545588281
>> [2] https://github.com/openjdk/crac/pull/60#discussion_r1185510445
>
> src/java.base/share/classes/jdk/crac/impl/ExceptionHolder.java line 37:
> 
>> 35:         E exception = get();
>> 36:         if (exception.getClass() == e.getClass()) {
>> 37:             for (Throwable t : e.getSuppressed()) {
> 
> We're losing the message and stack trace here. Previously, if the message was present it was added to the suppressed list as well.
> If you want to create aggregate-only exceptions (only suppressed list would be relevant) these should be declared as final, with only one no-arg constructor and stack trace collection disabled - but that would have some problems as discussed in https://github.com/openjdk/crac/pull/64/files#r1190679470

To avoid this PR grow too much, I basically agree with the comments, but still propose an aggregate exception, replied to the comment.

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PR Review Comment: https://git.openjdk.org/crac/pull/74#discussion_r1198015862