[nigrosimone]

Without an async context, napi_make_callback goes through the public node::MakeCallback(), which looks up the Environment from the creation context of the callback on every call. The napi_env already knows it, so call into it directly, as the path with an async context does. node_napi_env__::node_env() also looked it up from the context on every call (also in can_call_into_js()): now it is found once, a napi_env lives as long as its Environment.

There was no benchmark for napi_make_callback, so this adds napi/make_callback_napi, a C addon calling it from a libuv timer like an I/O callback.

Alone on 26.3.0 + #66316 the gain is inside the noise (-3.0% and +2.1%, no stars). With #66395 and the V8 checkpoint fast path (#66500) underneath, both now on main, it is +15% (200 to 174 ns), compare.js, 30 runs, Linux x64, one core:

                                     confidence improvement accuracy (*)   (**)  (***)
napi/make_callback_napi n=1000000           ***     15.12 %       ±4.73% ±6.29% ±8.19%
napi/make_callback_napi n=10000000          ***     14.78 %       ±3.82% ±5.10% ±6.68%

The Node-API callback tests and the make-callback addon tests pass. Part of the plan in nodejs/performance#24.

Disclosure: I used Opus 5.5 (Max) as coding assistant

[nodejs-github-bot]

Review requested:

• @nodejs/gyp
• @nodejs/node-api
• @nodejs/performance

[ronag]

Why still draft?

[nigrosimone]

No reason now. The gain needed #66395 and the V8 checkpoint fast path underneath, both are on main now. Marked ready.

[mcollina]

CI is red

[nigrosimone]

@mcollina CI is green now.

[codecov]

Codecov Report

❌ Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.71%. Comparing base (3e5c8af) to head (4000c25).
⚠️ Report is 261 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_api.cc	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66509      +/-   ##
==========================================
- Coverage   92.86%   90.71%   -2.15%     
==========================================
  Files         428      798     +370     
  Lines      195100   280024   +84924     
  Branches    30147    53866   +23719     
==========================================
+ Hits       181175   254025   +72850     
- Misses      13597    16287    +2690     
- Partials      328     9712    +9384     

Files with missing lines	Coverage Δ
src/api/callback.cc	80.54% <100.00%> (ø)
src/node_api_internals.h	100.00% <100.00%> (ø)
src/node_internals.h	80.35% <ø> (ø)
src/node_api.cc	77.18% <83.33%> (ø)

... and 545 files with indirect coverage changes

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