[jdk17] RFR: 8269865: Async UL needs to handle ERANGE on exceeding SEM_VALUE_MAX [v4]

[Xin Liu]

On Thu, 8 Jul 2021 00:23:17 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Xin Liu has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Use the new API signal_overflow of semaphore
>>   
>>   This patch handles overflow scenerios for Posix and Windows.
>>   MacOS platform doesn't have any error so we ignore it.
>
> src/hotspot/share/runtime/semaphore.hpp line 56:
> 
>> 54: 
>> 55:   // Ignore error of overflow
>> 56:   void signal_overflow(uint count = 1) {
> 
> I'm a bit unsure about how to name and describe this given that the overflow check only relates to debug builds - in a product build both `signal` and `signal_overflow` are identical.
> 
> I had missed previously that the `ignore_overflow` parameter was only in the impl API not the main public API.

Thanks you for reviewing this change. 

The reason we only had ignore_overflow in impl API because I defined my own platform-independent Semaphore class, aka. AsyncLogSemaphore in previous revision.  I changed type of _sem from Sempahore to AsyncLogSemaphore. I "overloaded" signal(uint count) in that way so  I don't  pollute "public API".


> I don't think this is necessary, just call wait(1, true) where needed.

I think your opinion is that it's not necessary.  how about I just add a second parameter ignore_overflow to Semaphore::signal with the default value = false?

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PR: https://git.openjdk.java.net/jdk17/pull/216