RFR: 8323807: Async UL: Add a stalling mode to async UL [v2]

[Johan Sjölen]

On Thu, 28 Mar 2024 06:37:30 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Johan Sjölen has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 41 additional commits since the last revision:
>> 
>>  - Merge remote-tracking branch 'origin/master' into ul-async-producer-consumer-take2
>>  - Missing N
>>  - Move constructors out of header file
>>  - Style
>>  - Correctly implement stalling
>>  - Missed one
>>  - Fix lossy conversions in tests
>>  - Merge remote-tracking branch 'origin/master' into ul-async-producer-consumer-take2
>>  - Only include sys/mman on Linux
>>  - Revert back to original Linux impl
>>  - ... and 31 more: https://git.openjdk.org/jdk/compare/064b91e3...8c4ced0f
>
> src/hotspot/share/logging/circularStringBuffer.cpp line 92:
> 
>> 90:     head(0) {}
>> 91: 
>> 92: size_t CircularStringBuffer::used() {
> 
> Is this API being drawn from some pre-existing code for circular buffers? I find the used/unused terminology a little unusual.

The head/tail terminology is straight from Linux kernel, but used/unused is of my own making AFAIK. What's a better pair of names? Allocated/unallocated?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17757#discussion_r1547338747