add initial jsg rust integration by anonrig · Pull Request #5378 · cloudflare/workerd

anonrig · 2025-10-22T19:45:48Z

Add Rust JSG bindings and comprehensive test coverage

This PR introduces Rust bindings for JSG, enabling
Rust code to interact with V8 and implement JavaScript APIs.

Key changes:

Add jsg crate with V8 bindings (Local/Global handles, types, resources)
Add jsg-macros for procedural macros (jsg_struct, jsg_resource, jsg_method)
Add jsg-test harness with proper Realm initialization for testing
Implement comprehensive test suite for JSG bindings
Add support for wrapping/unwrapping Rust resources in V8

The Rust JSG implementation provides type-safe V8 integration and will
enable more Rust-based APIs in workerd.

Example usage:

#[test]
fn objects_can_be_wrapped_and_unwrapped() {
    let harness = crate::Harness::new();
    harness.run_in_context(|isolate| unsafe {
        let mut lock = Lock::from_isolate(isolate);
        let instance = TestStruct {
            str: "test".to_string(),
        };
        let wrapped = instance.wrap(&mut lock);
        let mut obj: v8::Local<'_, v8::Object> = wrapped.into();
        assert!(obj.has(&mut lock, "str"));
        let str_value = obj.get(&mut lock, "str");
        assert!(str_value.unwrap().is_string());
        assert!(!obj.has(&mut lock, "test"));
        let value = "value".to_local(&mut lock);
        assert!(value.is_string());
        obj.set(&mut lock, "test", value);
        assert!(obj.has(&mut lock, "test"));
    });
}

github-actions · 2025-10-23T15:31:49Z

The generated output of @cloudflare/workers-types matches the snapshot in types/generated-snapshot 🎉

src/workerd/api/node/dns.h

src/rust/api/dns.rs

src/rust/jsg/ffi.c++

src/rust/jsg/jsg.h

Copilot

Pull request overview

This PR introduces comprehensive Rust bindings for the JSG (JavaScript Glue) system, enabling Rust code to interact with V8 and implement JavaScript APIs. The implementation provides type-safe V8 integration with support for wrapping/unwrapping Rust resources, procedural macros for reducing boilerplate, and a test harness with proper Realm initialization.

Key Changes:

Added core Rust JSG bindings (jsg crate) with V8 handle types (Local/Global), FFI bridges, and resource management
Implemented procedural macros (jsg-macros) for #[jsg_struct], #[jsg_resource], and #[jsg_method] to reduce boilerplate
Created test infrastructure (jsg-test) with proper V8 context setup for testing Rust JSG bindings
Integrated Rust-backed Node.js DNS implementation as a demonstration, conditionally enabled via autogate
Added Realm tracking for deterministic cleanup of Rust resources when V8 contexts are disposed

Reviewed changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 16 comments.

Show a summary per file

File	Description
`src/workerd/util/autogate.h`	Added `RUST_BACKED_NODE_DNS` autogate key for feature flagging
`src/workerd/util/autogate.c++`	Registered the new autogate key with its string representation
`src/workerd/jsg/wrappable.h`	Added `RUST_REALM` context slot and `WORKERD_RUST_WRAPPABLE_TAG` for Rust resources
`src/workerd/jsg/setup.h`	Exposed `getIsolate()` method for Rust FFI access to V8 isolate
`src/workerd/jsg/BUILD.bazel`	Added Rust JSG dependency and visibility for Rust packages
`src/workerd/io/worker.c++`	Integrated Realm creation/disposal in context lifecycle
`src/workerd/api/rtti.c++`	Added stub `addBuiltinModule` overload for future module registration
`src/workerd/api/node/node.h`	Conditionally registers C++ or Rust DNS implementation based on autogate
`src/workerd/api/node/BUILD.bazel`	Added Rust API dependency
`src/rust/jsg/v8.rs`	Core V8 FFI bindings with Local/Global handles and type conversions
`src/rust/jsg/modules.rs`	Module registration interface for Rust modules
`src/rust/jsg/lib.rs`	Core JSG types: Lock, Ref, Resource/Struct traits, Realm, and resource lifecycle
`src/rust/jsg/jsg.h`	C++ wrapper for Rust module registry integration
`src/rust/jsg/ffi.h`	FFI function declarations for V8 operations
`src/rust/jsg/ffi.c++`	FFI function implementations bridging Rust and V8 C++ APIs
`src/rust/jsg/ffi-inl.h`	Template implementations for FFI type conversions
`src/rust/jsg/BUILD.bazel`	Build configuration for JSG Rust crate and FFI library
`src/rust/jsg-test/lib.rs`	Test harness and comprehensive integration tests for JSG bindings
`src/rust/jsg-test/ffi.h`	Test harness interface declarations
`src/rust/jsg-test/ffi.c++`	Test harness implementation with V8 context setup
`src/rust/jsg-test/BUILD.bazel`	Build configuration for test infrastructure
`src/rust/jsg-macros/lib.rs`	Procedural macros for struct/resource/method code generation
`src/rust/jsg-macros/README.md`	Documentation for macro usage patterns
`src/rust/jsg-macros/BUILD.bazel`	Build configuration for proc macro crate
`src/rust/dns/lib.rs`	Added note about temporary duplication during migration
`src/rust/api/lib.rs`	Module registration entry point for Rust Node.js APIs
`src/rust/api/dns.rs`	Rust implementation of DNS utility with CAA/NAPTR record parsing
`src/rust/api/BUILD.bazel`	Build configuration for API crate
`patches/v8/0014-Add-another-slot-in-the-isolate-for-embedder.patch`	Increased V8 isolate data slots to accommodate Rust realm
`compile_flags.txt`	Added include paths for new Rust JSG modules

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src/rust/jsg/v8.rs

src/rust/jsg/lib.rs

src/rust/jsg-macros/lib.rs

src/rust/jsg/lib.rs

src/rust/jsg/ffi.c++

src/rust/jsg-macros/lib.rs

src/rust/jsg-test/lib.rs

patches/v8/0014-Add-another-slot-in-the-isolate-for-embedder.patch

src/rust/jsg/lib.rs

src/workerd/api/node/node.h

src/rust/jsg-macros/lib.rs

anonrig force-pushed the yagiz/rust-jsg-boilerplate branch from 89d6e2b to 01bc9ec Compare October 22, 2025 20:28

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anonrig force-pushed the yagiz/rust-jsg-boilerplate branch from f30d328 to 0fc6fee Compare October 27, 2025 17:47

jasnell reviewed Oct 27, 2025

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anonrig force-pushed the yagiz/rust-jsg-boilerplate branch 7 times, most recently from 7be536c to e218b33 Compare November 10, 2025 17:01

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anonrig mentioned this pull request Nov 17, 2025

Address and enhance small issues around dev tooling #5540

Merged

anonrig changed the title ~~start working on jsg/rust integration~~ add initial jsg rust integration Nov 17, 2025

anonrig force-pushed the yagiz/rust-jsg-boilerplate branch from 3f458ba to 1527967 Compare November 17, 2025 21:58

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anonrig mentioned this pull request Nov 19, 2025

add rust/jsg integration #4933

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anonrig force-pushed the yagiz/rust-jsg-boilerplate branch from 20579ac to 31942b8 Compare November 21, 2025 20:54

anonrig requested review from Copilot and mikea and removed request for erikcorry, fhanau, harrishancock and mikea November 25, 2025 03:14

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mamonaminyar1998 referenced this pull request Nov 25, 2025

feat(types): allow cmd-click into rpc props

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anonrig force-pushed the yagiz/rust-jsg-boilerplate branch 4 times, most recently from 10e6142 to cf9be8b Compare December 2, 2025 18:16

Add initial Rust JSG integration with error support

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anonrig force-pushed the yagiz/rust-jsg-boilerplate branch from cf9be8b to 1469fef Compare December 2, 2025 19:58

mikea merged commit ff9b8fa into main Dec 2, 2025
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mikea deleted the yagiz/rust-jsg-boilerplate branch December 2, 2025 22:53

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add initial jsg rust integration#5378

add initial jsg rust integration#5378
mikea merged 1 commit intomainfrom
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anonrig commented Oct 22, 2025 •

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