src: port `initializeImportMeta` to native #57286

aduh95 · 2025-03-03T09:51:47Z

Supersedes #57003.

We should probably avoid translating the URL to a path twice when the user needs both dirname and filename, but I'm not sure if there's an elegant way to do it without crossing the C++/JS bundary.

nodejs-github-bot · 2025-03-03T09:51:52Z

Review requested:

@nodejs/loaders

codecov · 2025-03-03T11:11:48Z

Codecov Report

Attention: Patch coverage is 77.27273% with 15 lines in your changes missing coverage. Please review.

Project coverage is 90.22%. Comparing base (6b0af17) to head (f38430c).
Report is 99 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_modules.cc	73.68%	4 Missing and 11 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #57286      +/-   ##
==========================================
- Coverage   90.24%   90.22%   -0.03%     
==========================================
  Files         630      629       -1     
  Lines      184908   184998      +90     
  Branches    36181    36225      +44     
==========================================
+ Hits       166874   166914      +40     
+ Misses      11061    11041      -20     
- Partials     6973     7043      +70

Files with missing lines	Coverage Δ
lib/internal/modules/esm/initialize_import_meta.js	`100.00% <100.00%> (ø)`
src/node_modules.cc	`78.32% <73.68%> (-0.69%)`	⬇️

... and 92 files with indirect coverage changes

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JakobJingleheimer

I'm not great with cpp, but it looks fine AFAICT, and conceptually checks out 🙂

lib/internal/modules/esm/initialize_import_meta.js

src/node_modules.cc

jsumners-nr

I think the original implementation is much easier to understand and maintain.

aduh95 · 2025-03-06T08:56:20Z

I think the original implementation is much easier to understand and maintain.

Do you have any suggestions on how to improve it?

Co-authored-by: Jacob Smith <[email protected]> Co-authored-by: Edy Silva <[email protected]>

jsumners-nr · 2025-03-10T11:51:47Z

I think the original implementation is much easier to understand and maintain.

Do you have any suggestions on how to improve it?

Not with it all being in C++. The original was plain JavaScript that only required JavaScript domain knowledge. This PR shifts it all in to C++, thus requiring the reader to know that language along with all of the underlying APIs used to implement the feature.

nodejs-github-bot · 2025-03-10T15:42:50Z

CI: https://ci.nodejs.org/job/node-test-pull-request/65676/
Benchmark CI: https://ci.nodejs.org/view/Node.js%20benchmark/job/benchmark-node-micro-benchmarks/1677/

Results

esm/cjs-parse.js n=100                                                                                                                                                         -0.20 %       ±0.89%
esm/detect-esm-syntax.js n=10000 type='with-package-json'                                                                                                                       0.41 %       ±0.99%
esm/detect-esm-syntax.js n=10000 type='without-package-json'                                                                                                                    0.25 %       ±0.79%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/non-exist' packageConfigMain='./index.js' packageJsonUrl='node_modules/test/package.json' n=10000                       0.12 %       ±0.76%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/non-exist' packageConfigMain='' packageJsonUrl='node_modules/test/package.json' n=10000                        ***      1.44 %       ±0.66%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.js' packageConfigMain='./index.js' packageJsonUrl='node_modules/test/package.json' n=10000          ***      1.35 %       ±0.56%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.js' packageConfigMain='' packageJsonUrl='node_modules/test/package.json' n=10000                     **      0.59 %       ±0.43%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.json' packageConfigMain='./index.js' packageJsonUrl='node_modules/test/package.json' n=10000                 0.76 %       ±0.86%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.json' packageConfigMain='' packageJsonUrl='node_modules/test/package.json' n=10000                           0.57 %       ±0.58%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.node' packageConfigMain='./index.js' packageJsonUrl='node_modules/test/package.json' n=10000         **      0.89 %       ±0.52%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.node' packageConfigMain='' packageJsonUrl='node_modules/test/package.json' n=10000                  ***      1.25 %       ±0.71%
esm/esm-loader-defaultResolve.js specifier='./relative-existing.js' n=1000                                                                                                      1.15 %       ±2.06%
esm/esm-loader-defaultResolve.js specifier='./relative-nonexistent.js' n=1000                                                                                                   0.02 %       ±1.16%
esm/esm-loader-defaultResolve.js specifier='node:os' n=1000                                                                                                                    -0.80 %       ±3.99%
esm/esm-loader-defaultResolve.js specifier='node:prefixed-nonexistent' n=1000                                                                                                  -1.62 %       ±4.91%
esm/esm-loader-defaultResolve.js specifier='unprefixed-existing' n=1000                                                                                                         0.47 %       ±1.24%
esm/esm-loader-defaultResolve.js specifier='unprefixed-nonexistent' n=1000                                                                                              **      1.11 %       ±0.68%
esm/esm-loader-import.js specifier='./relative-existing.js' n=1000                                                                                                              1.86 %       ±4.63%
esm/esm-loader-import.js specifier='./relative-nonexistent.js' n=1000                                                                                                           0.82 %       ±1.10%
esm/esm-loader-import.js specifier='data:text/javascript,{i}' n=1000                                                                                                           -1.30 %       ±1.70%
esm/esm-loader-import.js specifier='node:os' n=1000                                                                                                                            -1.84 %       ±3.60%
esm/esm-loader-import.js specifier='node:prefixed-nonexistent' n=1000                                                                                                           1.61 %       ±4.81%
esm/import-meta.js n=1000                                                                                                                                              ***     -5.10 %       ±0.61%
esm/require-esm.js n=1000 exports='default' type='access'                                                                                                                      -1.44 %       ±1.49%
esm/require-esm.js n=1000 exports='default' type='all'                                                                                                                 ***     -1.72 %       ±0.62%
esm/require-esm.js n=1000 exports='default' type='load'                                                                                                                  *     -0.64 %       ±0.51%
esm/require-esm.js n=1000 exports='named' type='access'                                                                                                                         1.15 %       ±1.81%
esm/require-esm.js n=1000 exports='named' type='all'                                                                                                                   ***     -1.53 %       ±0.57%
esm/require-esm.js n=1000 exports='named' type='load'                                                                                                                   **     -0.91 %       ±0.58%

aduh95 · 2025-03-13T15:36:57Z

Banchmark CI: https://ci.nodejs.org/view/Node.js%20benchmark/job/benchmark-node-micro-benchmarks/1680/

Results

confidence improvement accuracy (*)
esm/esm-loader-defaultResolve.js specifier='node:os' n=1000                       *     -3.36 %       ±2.64%
esm/esm-loader-defaultResolve.js specifier='node:prefixed-nonexistent' n=1000     *     -4.92 %       ±3.88%
esm/esm-loader-defaultResolve.js specifier='unprefixed-existing' n=1000          **     -1.88 %       ±1.37%
esm/esm-loader-import.js specifier='data:text/javascript,{i}' n=1000              *      1.51 %       ±1.27%
esm/import-meta.js n=1000                                                       ***     -4.65 %       ±0.53%
esm/require-esm.js n=1000 exports='default' type='access'                         *     -1.65 %       ±1.50%
esm/require-esm.js n=1000 exports='default' type='load'                         ***     -1.86 %       ±0.62%
esm/require-esm.js n=1000 exports='named' type='all'                            ***     -1.59 %       ±0.59%
esm/require-esm.js n=1000 exports='named' type='load'                           ***     -1.29 %       ±0.51%

This reverts commit d47b79b.

This reverts commit 434035e.

This reverts commit 42351cb.

aduh95 · 2025-03-13T15:59:48Z

Benchmark CI: https://ci.nodejs.org/view/Node.js%20benchmark/job/benchmark-node-micro-benchmarks/1682/

Results

confidence improvement accuracy (*)
esm/cjs-parse.js n=100                                                                                                                                                          1.09 %       ±1.13%
esm/detect-esm-syntax.js n=10000 type='with-package-json'                                                                                                                      -0.44 %       ±0.85%
esm/detect-esm-syntax.js n=10000 type='without-package-json'                                                                                                                    0.63 %       ±0.74%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/non-exist' packageConfigMain='./index.js' packageJsonUrl='node_modules/test/package.json' n=10000               **      1.05 %       ±0.68%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/non-exist' packageConfigMain='' packageJsonUrl='node_modules/test/package.json' n=10000                                 0.31 %       ±0.72%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.js' packageConfigMain='./index.js' packageJsonUrl='node_modules/test/package.json' n=10000                   0.62 %       ±0.64%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.js' packageConfigMain='' packageJsonUrl='node_modules/test/package.json' n=10000                             0.45 %       ±0.46%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.json' packageConfigMain='./index.js' packageJsonUrl='node_modules/test/package.json' n=10000                 0.39 %       ±0.76%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.json' packageConfigMain='' packageJsonUrl='node_modules/test/package.json' n=10000                           0.37 %       ±0.64%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.node' packageConfigMain='./index.js' packageJsonUrl='node_modules/test/package.json' n=10000                 0.65 %       ±0.72%
esm/esm-legacyMainResolve.js resolvedFile='node_modules/test/index.node' packageConfigMain='' packageJsonUrl='node_modules/test/package.json' n=10000                  ***      1.02 %       ±0.46%
esm/esm-loader-defaultResolve.js specifier='./relative-existing.js' n=1000                                                                                               *     -1.57 %       ±1.42%
esm/esm-loader-defaultResolve.js specifier='./relative-nonexistent.js' n=1000                                                                                                  -0.08 %       ±1.70%
esm/esm-loader-defaultResolve.js specifier='node:os' n=1000                                                                                                                    -0.26 %       ±2.28%
esm/esm-loader-defaultResolve.js specifier='node:prefixed-nonexistent' n=1000                                                                                                  -1.75 %       ±3.87%
esm/esm-loader-defaultResolve.js specifier='unprefixed-existing' n=1000                                                                                                         1.20 %       ±1.25%
esm/esm-loader-defaultResolve.js specifier='unprefixed-nonexistent' n=1000                                                                                                      0.48 %       ±0.87%
esm/esm-loader-import.js specifier='./relative-existing.js' n=1000                                                                                                             -1.16 %       ±3.86%
esm/esm-loader-import.js specifier='./relative-nonexistent.js' n=1000                                                                                                          -0.48 %       ±0.72%
esm/esm-loader-import.js specifier='data:text/javascript,{i}' n=1000                                                                                                           -0.41 %       ±1.82%
esm/esm-loader-import.js specifier='node:os' n=1000                                                                                                                            -1.91 %       ±3.28%
esm/esm-loader-import.js specifier='node:prefixed-nonexistent' n=1000                                                                                                           0.33 %       ±3.81%
esm/import-meta.js n=1000                                                                                                                                              ***     -5.62 %       ±0.69%
esm/require-esm.js n=1000 exports='default' type='access'                                                                                                               **     -2.03 %       ±1.45%
esm/require-esm.js n=1000 exports='default' type='all'                                                                                                                 ***     -1.31 %       ±0.62%
esm/require-esm.js n=1000 exports='default' type='load'                                                                                                                ***     -1.50 %       ±0.70%
esm/require-esm.js n=1000 exports='named' type='access'                                                                                                                        -0.42 %       ±1.68%
esm/require-esm.js n=1000 exports='named' type='all'                                                                                                                   ***     -1.19 %       ±0.49%
esm/require-esm.js n=1000 exports='named' type='load'                                                                                                                  ***     -1.06 %       ±0.46%

It's not any better, reverting

This reverts commit af8e8b1.

This reverts commit fa19ca4.

nodejs-github-bot · 2025-03-13T16:22:48Z

CI: https://ci.nodejs.org/job/node-test-pull-request/65721/

jasnell · 2025-03-13T16:39:08Z

src/node_modules.cc

@@ -579,6 +579,86 @@ void GetCompileCacheEntry(const FunctionCallbackInfo<Value>& args) {
      isolate, v8::Null(isolate), names.data(), values.data(), names.size()));
 }

+static void InitImportMetaLazyGetter(
+    Local<v8::Name> name, const v8::PropertyCallbackInfo<Value>& info) {


Nit: remove the v8:: qualifier and add v8::PropertyCallbackInfo to the using section at the top if it is not already there.

jasnell · 2025-03-13T17:42:41Z

src/node_modules.cc

+
+  node::Utf8Value url(isolate, info.Data());
+  // TODO(aduh95): Find a way to avoid calling Ada twice on module that access
+  // both `import.meta.dirname` and `import.meta.filename`.


Setting Data to a single internal object that has both dirname and filename set on it the first time either is accessed on it should work, yes?

jasnell · 2025-03-13T17:44:59Z

src/node_modules.cc

+    target
+        ->SetLazyDataProperty(
+            context, env->dirname_string(), InitImportMetaLazyGetter, args[1])
+        .Check();


Nit: can these please avoid the use of Check() and propagate errors up correctly?

jsumners-nr · 2025-03-13T19:14:50Z

Banchmark CI: ci.nodejs.org/view/Node.js%20benchmark/job/benchmark-node-micro-benchmarks/1680
Results

confidence improvement accuracy (*)
esm/esm-loader-defaultResolve.js specifier='node:os' n=1000                       *     -3.36 %       ±2.64%
esm/esm-loader-defaultResolve.js specifier='node:prefixed-nonexistent' n=1000     *     -4.92 %       ±3.88%
esm/esm-loader-defaultResolve.js specifier='unprefixed-existing' n=1000          **     -1.88 %       ±1.37%
esm/esm-loader-import.js specifier='data:text/javascript,{i}' n=1000              *      1.51 %       ±1.27%
esm/import-meta.js n=1000                                                       ***     -4.65 %       ±0.53%
esm/require-esm.js n=1000 exports='default' type='access'                         *     -1.65 %       ±1.50%
esm/require-esm.js n=1000 exports='default' type='load'                         ***     -1.86 %       ±0.62%
esm/require-esm.js n=1000 exports='named' type='all'                            ***     -1.59 %       ±0.59%
esm/require-esm.js n=1000 exports='named' type='load'                           ***     -1.29 %       ±0.51%

The actual benchmarks site is asking for a login. How do we interpret this snippet?

jasnell · 2025-03-13T20:28:38Z

hmm... looking at the benchmark results there it's just not clear to me that moving the init to native code has enough realized benefit. Moving into native does make the code a bit more difficult to maintain while also being slight slower. A lazy getter defined in JavaScript could likely achieve the same result while being easier for more people to help maintain. Not going to block on it tho... just not seeing the full benefit.

aduh95 · 2025-03-13T20:59:47Z

A lazy getter defined in JavaScript could likely achieve the same result while being easier for more people to help maintain

It's unclear whether a JS getter would be spec compliant, see the discussion in #57003 – that being said, I'm also a bit puzzled by the benchmark results

JakobJingleheimer · 2025-03-30T07:51:56Z

What you've done here is pretty cool. But if the c++ implementation isn't faster, and we can stay spec compliant (which that discussion seemed to end that it is), I think the JS implementation would be better because it's more maintainable.

src: port initializeImportMeta to native

62f0e9a

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. esm Issues and PRs related to the ECMAScript Modules implementation. needs-ci PRs that need a full CI run. labels Mar 3, 2025

aduh95 added 2 commits March 3, 2025 13:53

fixup! src: port initializeImportMeta to native

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fixup! src: port initializeImportMeta to native

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Co-authored-by: Jacob Smith <[email protected]> Co-authored-by: Edy Silva <[email protected]>

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aduh95 added 3 commits March 13, 2025 16:35

override both properties on first call

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side effect free

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do not compute dirname eagerly

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fixup! do not compute dirname eagerly

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Revert "fixup! do not compute dirname eagerly"

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This reverts commit d47b79b.

Revert "do not compute dirname eagerly"

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Revert "side effect free"

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This reverts commit 42351cb.

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fixup! override both properties on first call

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Revert "fixup! override both properties on first call"

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This reverts commit af8e8b1.

Revert "override both properties on first call"

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This reverts commit fa19ca4.

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src: port `initializeImportMeta` to native #57286

src: port `initializeImportMeta` to native #57286

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src: port initializeImportMeta to native #57286

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src: port `initializeImportMeta` to native #57286

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