refactor: move embedded runtime JS to real .js files (js2c)

.gitignore

@@ -22,6 +22,10 @@ thumbs.db
 
 .classpath
 android-runtime.iml
+
+# Emitted by tools/js2c.mjs from test-app/runtime/src/main/cpp/js during the build.
+test-app/runtime/src/main/cpp/generated/
+
 test-app/build-tools/*.log
 test-app/analytics/build-statistics.json
 package-lock.json

eslint.config.mjs

@@ -0,0 +1,38 @@
+// Lint setup for the runtime's builtin JavaScript
+// (test-app/runtime/src/main/cpp/js). Each file is compiled by BuiltinLoader
+// as a FUNCTION BODY with the fixed parameters `exports`, `module` and
+// `binding` (see that directory's README.md), which are declared as globals
+// here. no-undef is the typo net for binding-bag destructures and
+// native-global usage alike.
+import globals from 'globals';
+
+export default [
+  {
+    files: ['test-app/runtime/src/main/cpp/js/**/*.js'],
+    languageOptions: {
+      ecmaVersion: 2022,
+      sourceType: 'script',
+      globals: {
+        ...globals.es2021,
+        exports: 'readonly',
+        module: 'readonly',
+        binding: 'readonly',
+        global: 'readonly',
+        console: 'readonly',
+        URL: 'readonly',
+        URLSearchParams: 'readonly',
+        Blob: 'readonly',
+        File: 'readonly',
+        WebAssembly: 'readonly',
+        // Java package roots resolved through the metadata interceptor at
+        // runtime:
+        java: 'readonly',
+        org: 'readonly',
+      },
+    },
+    rules: {
+      'no-undef': 'error',
+      'no-unused-vars': ['error', { args: 'none', caughtErrors: 'none' }],
+    },
+  },
+];

package.json

@@ -27,11 +27,14 @@
   },
   "scripts": {
     "changelog": "conventional-changelog -p angular -i CHANGELOG.md -s",
+    "lint": "eslint test-app/runtime/src/main/cpp/js",
     "version": "npm run changelog && git add CHANGELOG.md"
   },
   "devDependencies": {
     "conventional-changelog-cli": "^2.1.1",
     "dayjs": "^1.11.7",
+    "eslint": "^9.15.0",
+    "globals": "^15.12.0",
     "semver": "^7.5.0"
   }
 }

test-app/runtime/CMakeLists.txt

@@ -58,6 +58,41 @@ include_directories(
         src/main/cpp/ada
 )
 
+# The runtime's builtin JavaScript (src/main/cpp/js) embedded into a generated
+# C++ table by tools/js2c.mjs. The list is explicit rather than globbed so that
+# adding a file is a visible build change; --check-dir fails the build when it
+# drifts from the directory contents.
+set(RUNTIME_BUILTIN_JS_DIR ${PROJECT_SOURCE_DIR}/src/main/cpp/js)
+set(RUNTIME_BUILTIN_JS
+        ${RUNTIME_BUILTIN_JS_DIR}/blob-url.js
+        ${RUNTIME_BUILTIN_JS_DIR}/error-events.js
+        ${RUNTIME_BUILTIN_JS_DIR}/events.js
+        ${RUNTIME_BUILTIN_JS_DIR}/json-helper.js
+        ${RUNTIME_BUILTIN_JS_DIR}/message-loop-timer.js
+        ${RUNTIME_BUILTIN_JS_DIR}/require-factory.js
+        ${RUNTIME_BUILTIN_JS_DIR}/smart-stringify.js
+        ${RUNTIME_BUILTIN_JS_DIR}/weak-ref.js
+)
+set(RUNTIME_BUILTINS_GENERATED_DIR ${PROJECT_SOURCE_DIR}/src/main/cpp/generated)
+get_filename_component(RUNTIME_BUILTINS_JS2C ${PROJECT_SOURCE_DIR}/../../tools/js2c.mjs ABSOLUTE)
+
+find_program(NODE_EXECUTABLE NAMES node nodejs)
+if (NOT NODE_EXECUTABLE)
+    message(FATAL_ERROR "node was not found on PATH; it is required to generate RuntimeBuiltins")
+endif ()
+
+add_custom_command(
+        OUTPUT ${RUNTIME_BUILTINS_GENERATED_DIR}/RuntimeBuiltins.h
+               ${RUNTIME_BUILTINS_GENERATED_DIR}/RuntimeBuiltins.cpp
+        COMMAND ${NODE_EXECUTABLE} ${RUNTIME_BUILTINS_JS2C}
+                --out-dir ${RUNTIME_BUILTINS_GENERATED_DIR}
+                --check-dir ${RUNTIME_BUILTIN_JS_DIR}
+                ${RUNTIME_BUILTIN_JS}
+        DEPENDS ${RUNTIME_BUILTIN_JS} ${RUNTIME_BUILTINS_JS2C}
+        COMMENT "Generating RuntimeBuiltins from src/main/cpp/js"
+        VERBATIM
+)
+
 if (OPTIMIZED_BUILD OR OPTIMIZED_WITH_INSPECTOR_BUILD)
     set(CMAKE_CXX_FLAGS "${COMMON_CMAKE_ARGUMENTS} -O3 -fvisibility=hidden -ffunction-sections -fno-data-sections")
 else ()
@@ -99,6 +134,7 @@ add_library(
         src/main/cpp/ArrayElementAccessor.cpp
         src/main/cpp/ArrayHelper.cpp
         src/main/cpp/AssetExtractor.cpp
+        src/main/cpp/BuiltinLoader.cpp
         src/main/cpp/CallbackHandlers.cpp
         src/main/cpp/ConcurrentQueue.cpp
         src/main/cpp/Constants.cpp
@@ -158,6 +194,8 @@ add_library(
         src/main/cpp/HMRSupport.cpp
         src/main/cpp/DevFlags.cpp
 
+        ${RUNTIME_BUILTINS_GENERATED_DIR}/RuntimeBuiltins.cpp
+
         # V8 inspector source files will be included only in Release mode
         ${INSPECTOR_SOURCES}
 )

test-app/runtime/src/main/cpp/BuiltinLoader.cpp

@@ -0,0 +1,116 @@
+#include "BuiltinLoader.h"
+
+#include <mutex>
+#include <vector>
+
+#include "ArgConverter.h"
+
+using namespace v8;
+
+namespace tns {
+
+namespace {
+
+/*
+ * Process-wide bytecode cache shared across isolates. Worker runtimes
+ * initialize on their own threads, so every access is under the mutex.
+ */
+std::mutex builtinCacheMutex;
+std::vector<uint8_t> builtinCache[static_cast<unsigned>(BuiltinId::kCount)];
+
+/*
+ * Every builtin is compiled as a function body receiving these fixed
+ * parameters, mirroring Node's module wrapper: a file exports through
+ * `module.exports`/`exports`, and natives arrive as properties of the
+ * `binding` bag (Node's internalBinding idiom) for each file to destructure.
+ */
+constexpr const char* kExportsParamName = "exports";
+constexpr const char* kModuleParamName = "module";
+constexpr const char* kBindingParamName = "binding";
+constexpr size_t kParamCount = 3;
+
+MaybeLocal<v8::Function> CompileBuiltin(Local<Context> context, BuiltinId id) {
+    Isolate* isolate = v8::Isolate::GetCurrent();
+    const BuiltinSource& builtin = GetBuiltinSource(id);
+    const unsigned index = static_cast<unsigned>(id);
+
+    // Copy the blob out so the shared slot can be refreshed concurrently while
+    // this compile still reads from the copy.
+    std::vector<uint8_t> blob;
+    {
+        std::lock_guard<std::mutex> lock(builtinCacheMutex);
+        blob = builtinCache[index];
+    }
+
+    ScriptOrigin origin(ArgConverter::ConvertToV8String(isolate, builtin.name));
+    Local<v8::String> sourceText = ArgConverter::ConvertToV8String(
+            isolate, builtin.source, static_cast<int>(builtin.length));
+    Local<v8::String> params[] = {
+            ArgConverter::ConvertToV8String(isolate, kExportsParamName),
+            ArgConverter::ConvertToV8String(isolate, kModuleParamName),
+            ArgConverter::ConvertToV8String(isolate, kBindingParamName)};
+
+    Local<v8::Function> fn;
+    if (!blob.empty()) {
+        // The Source owns and deletes the CachedData object; BufferNotOwned
+        // keeps the underlying bytes (our copy) out of its hands.
+        auto* cachedData = new ScriptCompiler::CachedData(
+                blob.data(), static_cast<int>(blob.size()),
+                ScriptCompiler::CachedData::BufferNotOwned);
+        ScriptCompiler::Source source(sourceText, origin, cachedData);
+        if (ScriptCompiler::CompileFunction(context, &source, kParamCount, params, 0, nullptr,
+                                            ScriptCompiler::kConsumeCodeCache)
+                    .ToLocal(&fn) &&
+            !cachedData->rejected) {
+            return fn;
+        }
+        // Rejected cache (e.g. produced under different flags): fall through
+        // and recompile eagerly so the refreshed blob covers inner functions
+        // again.
+    }
+
+    ScriptCompiler::Source source(sourceText, origin);
+    if (!ScriptCompiler::CompileFunction(context, &source, kParamCount, params, 0, nullptr,
+                                         ScriptCompiler::kEagerCompile)
+                 .ToLocal(&fn)) {
+        return MaybeLocal<v8::Function>();
+    }
+
+    std::unique_ptr<ScriptCompiler::CachedData> produced(
+            ScriptCompiler::CreateCodeCacheForFunction(fn));
+    if (produced != nullptr && produced->data != nullptr && produced->length > 0) {
+        std::lock_guard<std::mutex> lock(builtinCacheMutex);
+        builtinCache[index].assign(produced->data, produced->data + produced->length);
+    }
+
+    return fn;
+}
+
+}  // namespace
+
+MaybeLocal<Value> BuiltinLoader::RunBuiltin(Local<Context> context, BuiltinId id,
+                                            Local<Value> binding) {
+    Isolate* isolate = v8::Isolate::GetCurrent();
+
+    Local<v8::Function> fn;
+    if (!CompileBuiltin(context, id).ToLocal(&fn)) {
+        return MaybeLocal<Value>();
+    }
+
+    Local<Object> exportsObj = Object::New(isolate);
+    Local<Object> moduleObj = Object::New(isolate);
+    Local<v8::String> exportsKey = ArgConverter::ConvertToV8String(isolate, kExportsParamName);
+    if (!moduleObj->Set(context, exportsKey, exportsObj).FromMaybe(false)) {
+        return MaybeLocal<Value>();
+    }
+
+    Local<Value> args[] = {exportsObj, moduleObj,
+                           binding.IsEmpty() ? Undefined(isolate).As<Value>() : binding};
+    if (fn->Call(context, Undefined(isolate), static_cast<int>(kParamCount), args).IsEmpty()) {
+        return MaybeLocal<Value>();
+    }
+
+    return moduleObj->Get(context, exportsKey);
+}
+
+}  // namespace tns

test-app/runtime/src/main/cpp/BuiltinLoader.h

@@ -0,0 +1,29 @@
+#ifndef BUILTINLOADER_H_
+#define BUILTINLOADER_H_
+
+#include "generated/RuntimeBuiltins.h"
+#include "v8.h"
+
+namespace tns {
+
+class BuiltinLoader {
+public:
+    /*
+     * Compiles the builtin identified by id as a function body with the fixed
+     * parameters `exports`, `module` and `binding` (Node's module wrapper plus
+     * its internalBinding idiom), calls it with the given bag of natives (or
+     * undefined when omitted), and returns the resulting `module.exports`.
+     * Scripts carry an "internal/<name>.js" origin so runtime frames are
+     * identifiable in stack traces. Compilation goes through a process-wide
+     * bytecode cache: the first run in the process compiles eagerly and
+     * populates the cache, later isolates (workers, which run on their own
+     * threads) consume it instead of re-parsing the source.
+     */
+    static v8::MaybeLocal<v8::Value> RunBuiltin(
+            v8::Local<v8::Context> context, BuiltinId id,
+            v8::Local<v8::Value> binding = v8::Local<v8::Value>());
+};
+
+}  // namespace tns
+
+#endif /* BUILTINLOADER_H_ */