Commit d5457f5f authored by Stephen Belanger's avatar Stephen Belanger Committed by Commit Bot
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[api] JSFunction PromiseHook for v8::Context

This will enable Node.js to get much better performance from async_hooks
as currently PromiseHook delegates to C++ for the hook function and then
Node.js delegates it right back to JavaScript, introducing several
unnecessary barrier hops in code that gets called very, very frequently
in modern, promise-heavy applications.

This API mirrors the form of the original C++ function based PromiseHook
API, however it is intentionally separate to allow it to use JSFunctions
triggered within generated code to, as much as possible, avoid entering
runtime functions entirely.

Because PromiseHook has internal use also, beyond just the Node.js use,
I have opted to leave the existing API intact and keep this separate to
avoid conflicting with any possible behaviour expectations of other API
users.

The design ideas for this new API stemmed from discussion with some V8
team members at a previous Node.js Diagnostics Summit hosted by Google
in Munich, and the relevant documentation of the discussion can be found
here: https://docs.google.com/document/d/1g8OrG5lMIUhRn1zbkutgY83MiTSMx-0NHDs8Bf-nXxM/edit#heading=h.w1bavzz80l1e

A summary of the reasons for why this new design is important can be
found here: https://docs.google.com/document/d/1vtgoT4_kjgOr-Bl605HR2T6_SC-C8uWzYaOPDK5pmRo/edit?usp=sharing

Bug: v8:11025
Change-Id: I0b403b00c37d3020b5af07b654b860659d3a7697
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2759188


Reviewed-by: default avatarMarja Hölttä <marja@chromium.org>
Reviewed-by: default avatarCamillo Bruni <cbruni@chromium.org>
Reviewed-by: default avatarAnton Bikineev <bikineev@chromium.org>
Reviewed-by: default avatarIgor Sheludko <ishell@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73858}
parent b377f67f
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