add rust backed node buffer implementation

deps/rust/BUILD.bazel

@@ -65,6 +65,15 @@ crates_vendor(
                 "lol_html_c_api_include_lol_html_h": "include/lol_html.h",
             },
         )],
+        # simdutf compiles C++ via the cc crate; workerd uses libc++ not libstdc++.
+        # build_script_toolchains provides Bazel's C++ toolchain to the cc crate
+        # so it uses the same clang/libc++ as workerd. CXXSTDLIB tells cc to link libc++.
+        "simdutf": [crate.annotation(
+            build_script_env = {
+                "CXXSTDLIB": "c++",
+            },
+            build_script_toolchains = ["@bazel_tools//tools/cpp:current_cc_toolchain"],
+        )],
     },
     cargo_bazel = CARGO_BAZEL,
     cargo_lockfile = "//deps/rust:Cargo.lock",

deps/rust/cargo.bzl

@@ -28,6 +28,7 @@ PACKAGES = WORKERD_CXX_PACKAGES | {
     "ruff_python_parser": crate.spec(git = "https://github.com/astral-sh/ruff", tag = "0.12.1"),
     # param_extractor depends on unbounded_depth feature
     "serde_json": crate.spec(version = "1", features = ["unbounded_depth"]),
+    "simdutf": crate.spec(version = "0"),
     "serde": crate.spec(version = "1", features = ["derive"]),
     "thiserror": crate.spec(version = "2"),
     # tokio is huge, let's enable only features when we actually need them.

deps/rust/crates/BUILD.bazel

@@ -337,6 +337,18 @@ alias(
     tags = ["manual"],
 )
 
+alias(
+    name = "simdutf-0.7.0",
+    actual = "@crates_vendor__simdutf-0.7.0//:simdutf",
+    tags = ["manual"],
+)
+
+alias(
+    name = "simdutf",
+    actual = "@crates_vendor__simdutf-0.7.0//:simdutf",
+    tags = ["manual"],
+)
+
 alias(
     name = "static_assertions-1.1.0",
     actual = "@crates_vendor__static_assertions-1.1.0//:static_assertions",

deps/rust/crates/BUILD.simdutf-0.7.0.bazel

@@ -0,0 +1,54 @@
+###############################################################################
+# @generated
+# DO NOT MODIFY: This file is auto-generated by a crate_universe tool. To
+# regenerate this file, run the following:
+#
+#     bazel run @@//deps/rust:crates_vendor
+###############################################################################
+#
+# MANUALLY PATCHED: The simdutf Rust crate normally compiles its own copy of
+# the simdutf C++ library via a build script. Since workerd already vendors
+# simdutf as @simdutf//:simdutf (which exports the simdutf_* extern "C"
+# functions that the Rust crate expects), we skip the build script entirely
+# and link directly against workerd's copy.
+
+load("@rules_rust//rust:defs.bzl", "rust_library")
+
+package(default_visibility = ["//visibility:public"])
+
+rust_library(
+    name = "simdutf",
+    srcs = glob(
+        include = ["**/*.rs"],
+        allow_empty = True,
+    ),
+    compile_data = glob(
+        include = ["**"],
+        allow_empty = True,
+        exclude = [
+            "**/* *",
+            ".tmp_git_root/**/*",
+            "BUILD",
+            "BUILD.bazel",
+            "WORKSPACE",
+            "WORKSPACE.bazel",
+        ],
+    ),
+    crate_root = "src/lib.rs",
+    edition = "2021",
+    rustc_flags = [
+        "--cap-lints=allow",
+    ],
+    tags = [
+        "cargo-bazel",
+        "crate-name=simdutf",
+        "manual",
+        "noclippy",
+        "norustfmt",
+    ],
+    version = "0.7.0",
+    deps = [
+        "@crates_vendor__bitflags-2.11.0//:bitflags",
+        "@simdutf",
+    ],
+)

deps/rust/crates/defs.bzl

@@ -319,6 +319,7 @@ _NORMAL_DEPENDENCIES = {
             "scratch": Label("@crates_vendor//:scratch-1.0.9"),
             "serde": Label("@crates_vendor//:serde-1.0.228"),
             "serde_json": Label("@crates_vendor//:serde_json-1.0.149"),
+            "simdutf": Label("@crates_vendor//:simdutf-0.7.0"),
             "static_assertions": Label("@crates_vendor//:static_assertions-1.1.0"),
             "swc_common": Label("@crates_vendor//:swc_common-18.0.1"),
             "swc_ts_fast_strip": Label("@crates_vendor//:swc_ts_fast_strip-43.0.0"),
@@ -2059,6 +2060,16 @@ def crate_repositories():
         build_file = Label("//deps/rust/crates:BUILD.simd-adler32-0.3.8.bazel"),
     )
 
+    maybe(
+        http_archive,
+        name = "crates_vendor__simdutf-0.7.0",
+        sha256 = "5f542752c7335a9174e7bb81112c3ca1415a7a6b6ec2c3e840aca347a30f9141",
+        type = "tar.gz",
+        urls = ["https://static.crates.io/crates/simdutf/0.7.0/download"],
+        strip_prefix = "simdutf-0.7.0",
+        build_file = Label("//deps/rust/crates:BUILD.simdutf-0.7.0.bazel"),
+    )
+
     maybe(
         http_archive,
         name = "crates_vendor__siphasher-0.3.11",
@@ -2855,6 +2866,7 @@ def crate_repositories():
         struct(repo = "crates_vendor__scratch-1.0.9", is_dev_dep = False),
         struct(repo = "crates_vendor__serde-1.0.228", is_dev_dep = False),
         struct(repo = "crates_vendor__serde_json-1.0.149", is_dev_dep = False),
+        struct(repo = "crates_vendor__simdutf-0.7.0", is_dev_dep = False),
         struct(repo = "crates_vendor__static_assertions-1.1.0", is_dev_dep = False),
         struct(repo = "crates_vendor__swc_common-18.0.1", is_dev_dep = False),
         struct(repo = "crates_vendor__swc_ts_fast_strip-43.0.0", is_dev_dep = False),

src/rust/api/BUILD.bazel

@@ -11,6 +11,8 @@ wd_rust_crate(
     visibility = ["//visibility:public"],
     deps = [
         "//src/rust/jsg",
+        "//src/rust/nbytes",
+        "@crates_vendor//:simdutf",
         "@crates_vendor//:thiserror",
     ],
 )