[OV JS] Improve Core.importModel implementation: SharedStreamBuffer + variant source #33658

Nishant-ZFYII · 2026-01-17T05:35:56Z

What / Why

This refactors the Node.js bindings for Core.importModelSync() and Core.importModel().

The async Buffer path was still going through std::string → std::stringstream, which adds extra copies. Also, the async worker didn’t cleanly separate “import from stream bytes” vs “import from tensor”, so it was easy to end up treating tensor data like a stream. This change switches Buffer imports to ov::SharedStreamBuffer and makes the async worker explicitly dispatch based on input type.

No JS API changes — just internal implementation cleanup.

What changed

Buffer imports (sync + async) now use ov::SharedStreamBuffer + std::istream instead of building a std::stringstream.
ImportModelContext now stores the input as std::variant<std::monostate, BufferSource, TensorSource>.
- BufferSource keeps a persistent reference to the JS Buffer so it can’t be GC’d while the worker is running, and wraps the underlying bytes with ov::SharedStreamBuffer.
- TensorSource keeps a persistent reference to the JS object backing TensorWrap, and stores ov::Tensor directly.
importModelThread uses std::visit to call the right ov::Core::import_model overload (stream vs tensor).
Exceptions in the native worker are surfaced to JS by rejecting the Promise with an Error.
Updated the unit test that checks signature-validation error strings (the allowed-signatures output changed with the refactor).

Files changed

src/bindings/js/node/include/core_wrap.hpp
src/bindings/js/node/src/core_wrap.cpp
src/bindings/js/node/tests/unit/basic.test.js

Checks

Ran:

npm run lint
npm run format
npm test

CC: @almilosz @Retribution98

…or sources - Add required includes: <variant>, <istream>, <memory>, shared_buffer.hpp - Replace std::stringstream with std::variant<monostate, BufferSource, TensorSource> - BufferSource: pins JS Buffer with ObjectReference, stores SharedStreamBuffer - TensorSource: pins JS TensorWrap, stores ov::Tensor directly - Add _error_msg field for proper async error propagation - Use ov::AnyMap instead of std::map<std::string, ov::Any> Part of issue openvinotoolkit#33601: Improve implementation of Node.js API Core.import_model()

- Add required includes: <type_traits>, tensor.hpp, shared_buffer.hpp - Replace direct _stream access with std::visit over source variant - BufferSource: create local std::istream over SharedStreamBuffer - TensorSource: call import_model(tensor, ...) directly - Add try/catch with proper Promise rejection on error - Handle both std::exception and unknown exceptions Part of issue openvinotoolkit#33601: Improve implementation of Node.js API Core.import_model()

…nsor support - Replace std::string + std::stringstream with ov::SharedStreamBuffer (zero-copy) - Add Tensor input support using cast_to_tensor and direct tensor overload - Use ov::js::validate pattern for consistent argument validation - Use ov::AnyMap for config consistency - Proper static_cast for Buffer length to size_t Part of issue openvinotoolkit#33601: Improve implementation of Node.js API Core.import_model()

- Use std::make_unique for RAII safety (no leak if setup throws) - Add Tensor input support: pin TensorWrap with ObjectReference - Buffer input: pin JS Buffer, use SharedStreamBuffer (zero-copy) - Store source in variant, worker thread dispatches via std::visit - Consistent ov::AnyMap usage for config Part of issue openvinotoolkit#33601: Improve implementation of Node.js API Core.import_model()

Auto-format core_wrap.hpp and core_wrap.cpp to match project code style.

- importModelSync now uses ov::js::validate() and reports standardized parameter mismatch errors - Update basic.test.js to assert on the new stable error message instead of legacy per-arg type strings Part of issue openvinotoolkit#33601: Improve implementation of Node.js API Core.import_model()

almilosz · 2026-01-21T08:53:21Z

build_jenkins

almilosz

Thanks for the PR! I left a few comments

src/bindings/js/node/src/core_wrap.cpp

src/bindings/js/node/tests/unit/basic.test.js

src/bindings/js/node/src/core_wrap.cpp

- Remove explicit casts in SharedStreamBuffer construction - Use overloaded helper for std::visit instead of if constexpr chain - Remove redundant data/size fields from BufferSource struct - Use raw new with try-catch guard instead of make_unique + release - Remove unnecessary regex escape in test assertions - Add test for importModel promise rejection on invalid buffer

almilosz · 2026-01-26T20:11:57Z

build_jenkins

almilosz · 2026-01-26T20:18:51Z

Hey, I can see that all my comments are addressed, thank you. Unfortunately, code style check failed :( do you need help with fixing it?

Nishant-ZFYII · 2026-01-27T08:58:28Z

Thanks @almilosz for the careful review and being patient with me — appreciate it!

I ran clang-format-18 locally via cmake --build . --target clang_format_fix_all, verified with clang_format_check_all, and pushed a formatting-only commit. I followed the repo guidelines in docs/dev/coding_style.md.

Could you please take another look when you have a moment? If anything is still not aligned with the expected style checks, I’m happy to adjust.Thanks again for offering to help — really appreciate it.

almilosz · 2026-01-27T12:01:38Z

Over 300 files is changed. Only changes to files you modified should stay

Nishant-ZFYII · 2026-01-27T13:06:35Z

Apologies for the noise on that last push — I ran clang_format_fix_all and did git add . Which caused the huge file dump

I've reset that commit and force-pushed a clean one that applies clang-format only to core_wrap.cpp (the only file that needed formatting changes).

almilosz · 2026-01-29T08:55:37Z

build_jenkins

almilosz · 2026-02-03T15:53:28Z

build_jenkins

praasz · 2026-02-04T08:37:03Z

src/bindings/js/node/include/core_wrap.hpp

+    };
+
+    using Source = std::variant<std::monostate, BufferSource, TensorSource>;
+    Source source{std::monostate{}};


Suggested change

Source source{std::monostate{}};

Source source{};

It should use first variant as default initializer

praasz · 2026-02-04T08:37:40Z

src/bindings/js/node/src/core_wrap.cpp


+// Helper for std::visit with multiple lambdas
+template <class... Ts>
+struct overloaded : Ts... {


There is helper in OV with this implementation variant_visitor.hpp

praasz · 2026-02-04T08:38:50Z

src/bindings/js/node/src/core_wrap.cpp

+        context->_compiled_model =
+            std::visit(overloaded{
+                           [](std::monostate&) -> ov::CompiledModel {
+                               throw std::runtime_error("ImportModelContext source not initialized");


Why not OPENVINO_THROW/ASSERT is not used?

Nishant-ZFYII added 6 commits January 17, 2026 10:16

[OV JS] Apply clang-format-18 formatting

7877ee7

Auto-format core_wrap.hpp and core_wrap.cpp to match project code style.

Nishant-ZFYII requested a review from a team as a code owner January 17, 2026 05:35

github-actions bot added the category: JS API OpenVino JS API Bindings label Jan 17, 2026

sys-openvino-ci added the ExternalPR External contributor label Jan 17, 2026

Merge branch 'master' into js-importmodel-sharedstreambuffer-variant

5f4758e

Nishant-ZFYII mentioned this pull request Jan 18, 2026

[JS API] Add import_model(tensor) to Node.js API #33401

Merged

almilosz reviewed Jan 21, 2026

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Nishant-ZFYII requested review from a team as code owners January 27, 2026 08:06

Nishant-ZFYII requested review from ValentinaKats, akuporos and p-wysocki and removed request for a team January 27, 2026 08:06

github-actions bot added category: CPU OpenVINO CPU plugin category: build OpenVINO cmake script / infra category: docs OpenVINO documentation labels Jan 27, 2026

github-actions bot added category: ONNX FE OpenVINO ONNX FrontEnd category: dependency_changes Pull requests that update a dependency file category: docker_env labels Jan 27, 2026

Nishant-ZFYII requested a review from almilosz January 27, 2026 09:05

node: apply clang-format to core_wrap.cpp

47cb1a5

Nishant-ZFYII force-pushed the js-importmodel-sharedstreambuffer-variant branch from e94aa96 to 47cb1a5 Compare January 27, 2026 13:02

github-actions bot removed category: CPU OpenVINO CPU plugin category: build OpenVINO cmake script / infra category: docs OpenVINO documentation category: ONNX FE OpenVINO ONNX FrontEnd category: dependency_changes Pull requests that update a dependency file category: docker_env labels Jan 27, 2026

almilosz removed request for a team, ValentinaKats, akuporos and p-wysocki January 27, 2026 13:48

Merge branch 'master' into js-importmodel-sharedstreambuffer-variant

69df8c4

almilosz approved these changes Feb 3, 2026

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almilosz added this pull request to the merge queue Feb 4, 2026

praasz removed this pull request from the merge queue due to a manual request Feb 4, 2026

praasz reviewed Feb 4, 2026

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[OV JS] Improve Core.importModel implementation: SharedStreamBuffer + variant source #33658

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[OV JS] Improve Core.importModel implementation: SharedStreamBuffer + variant source #33658

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Nishant-ZFYII commented Jan 17, 2026

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