On Tue, Aug 4, 2020 at 1:32 PM Adrienne Walker <e...@chromium.org> wrote:
> On Thu, Jul 30, 2020 at 9:57 PM Ben Noordhuis <i...@bnoordhuis.nl> wrote: > >> On Thu, Jul 30, 2020 at 8:21 PM Adrienne Walker <e...@chromium.org> >> wrote: >> > Is there any way to know from a v8::Value whether serializing it will >> have side effects (at all or on particular properties)? >> >> Apart from checking whether it's primitive (v->IsNullOrUndefined() || >> v->IsBoolean() || ...), I believe the answer is 'no' . Non-primitive >> values can have getters and getters execute arbitrary code. >> >> Checking for only simple properties recursively is an option but >> probably not faster and you'll need to handle cycles and a ton of edge >> cases (what if the property is a pending promise? what if it's a >> WeakMap? etc.) >> > > Can I use HasRealNamedProperty/GetRealNamedProperty to see if I can access > those properties without side effects and then check if those values are > primitive from there? I suspect that most indexeddb keys being provided > here are primitive string values inside a single simple object, and so am I > trying to figure out how to fast path this case. Is there a way to tell if > a property is one of these complicated edge cases that you mention? > > >> The debugger has a "side-effect-free evaluate" mode but that operates >> on functions, not values. You could use it to check getters for side >> effects (and promises, and...) but the algorithm is conservative (can >> report side effects when there are none) and runs in O(n) time >> relative to the function's bytecode size. > > > Given the potential performance issues there, this doesn't sound like a > plausible approach. > > The only other thing we thought of was if there was some way to have some > sort of observer as a part of serialization that could record the values > without having to deserialize again to access. I worry that this might be > too invasive to v8's serialization though. > To the question of whether something might be "invasive to v8's serialization", I think the history here is important: serialization used to live in Blink, but was moved into V8 (by jbroman@, CCed) for performance reasons. Given that the problem you're investigating is another performance issue in serialization, making such an invasive change should at least be on the table, I'd argue. - Adam > -- > -- > v8-users mailing list > v8-users@googlegroups.com > http://groups.google.com/group/v8-users > --- > You received this message because you are subscribed to the Google Groups > "v8-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to v8-users+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/v8-users/CA%2B1_fV8rAhA8arck6C%2BXoQC%3DaMx1S_cARXGbymiG-%3DCHko3_5Q%40mail.gmail.com > <https://groups.google.com/d/msgid/v8-users/CA%2B1_fV8rAhA8arck6C%2BXoQC%3DaMx1S_cARXGbymiG-%3DCHko3_5Q%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-users/CAEvLGcKNeUQi-Spsyv95vi64dmw%2BGk6DyVOzVQ2kMX64QLsumA%40mail.gmail.com.
