What's the use case of returning a pointer from a v8 fast api? On Monday, April 28, 2025 at 4:50:32 AM UTC-4 aapo.al...@gmail.com wrote:
> Don't forget about pointers! Those can be returned as well :) > > On Monday, 28 April 2025 at 09:48:28 UTC+3 ah...@google.com wrote: > >> Hi, >> >> I would say the V8 Fast API is still considered unstable. Since many >> limitations were removed, not only the documentation but also the APIs are >> out-dated and would benefit from cleanup. However, since old APIs have to >> be deprecated before they can be changed, this takes some time. >> >> When it comes to arguments, there are some subtle limitations left, see >> [1], but those are platform-specific. Mostly all limitations should be >> gone. I will go over the documentation and update it. When it comes to >> return values, then indeed, as you noted, objects and strings cannot be >> returned, only integers, floats, and void. >> >> The heuristics of CFunction overloads depends now only on the number of >> arguments. If an API function is called in JavaScript with n parameters, >> then it will call the C++ function which expects n parameters. If no such >> C++ exists, then no fast call is happening. If the API has overloads or >> optional parameters, then this has to be resolved by the C++ functions. >> There should not be two CFunctions with the same number of arguments, >> although I'm not sure if we are checking for that. >> >> Unfortunately, `FastOneByteString` is faster than what you can achieve >> with a `v8::Local<v8::Value>` parameter, when you use `FastOneByteString`, >> you should not trigger a GC. >> >> Cheers, Andreas >> >> [1] >> https://source.chromium.org/chromium/chromium/src/+/main:v8/src/compiler/fast-api-calls.cc;l=65;drc=2bf826180ca85d007fb39024ff18322fa4635efb >> >> On Thu, Apr 24, 2025 at 10:17 PM 'Yagiz Nizipli' via v8-dev < >> v8-...@googlegroups.com> wrote: >> >>> We are actively investigating/working on adding V8 Fast API support for >>> Cloudflare Workers. While looking at the v8-fast-api-calls.h file (ref: >>> https://github.com/v8/v8/blob/main/include/v8-fast-api-calls.h) , I >>> realized that some of the documentation referencing the limitations are not >>> correct and up to date. >>> >>> I'm more than happy to update the header file to reflect the current >>> state of the implementation, but first, I'd like to ask couple of >>> questions to understand the implementation better. >>> >>> - Is V8 Fast API considered unstable? >>> - Since V8 fast api can now allocate, trigger JS and GC, which >>> limitations still apply? Looking at line 24, I believe these comments are >>> not valid. >>> - What is the heuristics of CFunction overloads? In an example where a >>> function has a required and an optional parameter, is it sufficient to add >>> 2 functions, method(a) and method(a, b)? What is the behavior if the user >>> calls this method with 3 arguments? Would it trigger method(a,b)? Is the >>> order MemorySpan CFunctions make a difference? Since v8::Local<Value> is >>> supported, it seems we can get away with a CFunction that has a second >>> parameter of v8::Local<Value> for the optional parameter. >>> - Since v8 fast api supports v8::Local<v8::Value> now, is there any >>> particular reason for using FastOneByteString over v8 local value for one >>> byte strings? >>> - By looking at the documentation, the only limitations I could think of >>> are the ones related to the return type of CFunction, which doesn't allow >>> returning objects/values/strings. What are the actual limitations of V8 >>> fast api? >>> >>> Thank you for your help. >>> >>> -- >>> -- >>> v8-dev mailing list >>> v8-...@googlegroups.com >>> http://groups.google.com/group/v8-dev >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "v8-dev" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to v8-dev+un...@googlegroups.com. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/v8-dev/08d9e03f-9db2-47c9-98ce-72c464c72475n%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/v8-dev/08d9e03f-9db2-47c9-98ce-72c464c72475n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> >> -- >> >> Andreas Haas >> >> Software Engineer >> >> ah...@google.com >> >> >> Google Germany GmbH >> >> Erika-Mann-Straße 33 >> >> 80636 München >> >> >> Geschäftsführer: Paul Manicle, Liana Sebastian >> >> Registergericht und -nummer: Hamburg, HRB 86891 >> >> Sitz der Gesellschaft: Hamburg >> >> >> Diese E-Mail ist vertraulich. Falls Sie diese fälschlicherweise erhalten >> haben sollten, leiten Sie diese bitte nicht an jemand anderes weiter, >> löschen Sie alle Kopien und Anhänge davon und lassen Sie mich bitte wissen, >> dass die E-Mail an die falsche Person gesendet wurde. >> >> >> >> This e-mail is confidential. If you received this communication by >> mistake, please don't forward it to anyone else, please erase all copies >> and attachments, and please let me know that it has gone to the wrong >> person. >> >> -- -- v8-dev mailing list v8-dev@googlegroups.com http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-dev+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/v8-dev/cd8bcced-8fe8-4e8a-9a99-485b8dfa3eben%40googlegroups.com.
