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/851ebc5f-682e-487b-b438-fbd5440cae9fn%40googlegroups.com.
