sea: add support for V8 bytecode-only caching

Refs: nodejs/single-executable#73
Signed-off-by: Darshan Sen <raisinten@gmail.com>
PR-URL: #48191
Fixes: nodejs/single-executable#73
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

doc/api/single-executable-applications.md

@@ -10,6 +10,9 @@ changes:
   - version: REPLACEME
     pr-url: https://github.com/nodejs/node/pull/46824
     description: Added support for "useSnapshot".
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/48191
+    description: Added support for "useCodeCache".
 -->
 
 > Stability: 1 - Experimental: This feature is being designed and will change.
@@ -174,7 +177,8 @@ The configuration currently reads the following top-level fields:
   "main": "/path/to/bundled/script.js",
   "output": "/path/to/write/the/generated/blob.blob",
   "disableExperimentalSEAWarning": true, // Default: false
-  "useSnapshot": false  // Default: false
+  "useSnapshot": false,  // Default: false
+  "useCodeCache": true // Default: false
 }
 ```
 
@@ -213,6 +217,18 @@ and the main script can use the [`v8.startupSnapshot` API][] to adapt to
 these constraints. See
 [documentation about startup snapshot support in Node.js][].
 
+### V8 code cache support
+
+When `useCodeCache` is set to `true` in the configuration, during the generation
+of the single executable preparation blob, Node.js will compile the `main`
+script to generate the V8 code cache. The generated code cache would be part of
+the preparation blob and get injected into the final executable. When the single
+executable application is launched, instead of compiling the `main` script from
+scratch, Node.js would use the code cache to speed up the compilation, then
+execute the script, which would improve the startup performance.
+
+**Note:** `import()` does not work when `useCodeCache` is `true`.
+
 ## Notes
 
 ### `require(id)` in the injected module is not file based

lib/internal/modules/cjs/loader.js

@@ -1123,7 +1123,7 @@ Module.prototype.require = function(id) {
 let resolvedArgv;
 let hasPausedEntry = false;
 let Script;
-function wrapSafe(filename, content, cjsModuleInstance) {
+function wrapSafe(filename, content, cjsModuleInstance, codeCache) {
   if (patched) {
     const wrapper = Module.wrap(content);
     if (Script === undefined) {
@@ -1158,13 +1158,21 @@ function wrapSafe(filename, content, cjsModuleInstance) {
       '__dirname',
     ], {
       filename,
+      cachedData: codeCache,
       importModuleDynamically(specifier, _, importAssertions) {
         const cascadedLoader = getCascadedLoader();
         return cascadedLoader.import(specifier, normalizeReferrerURL(filename),
                                      importAssertions);
       },
     });
 
+    // The code cache is used for SEAs only.
+    if (codeCache &&
+        result.cachedDataRejected !== false &&
+        internalBinding('sea').isSea()) {
+      process.emitWarning('Code cache data rejected.');
+    }
+
     // Cache the source map for the module if present.
     if (result.sourceMapURL) {
       maybeCacheSourceMap(filename, content, this, false, undefined, result.sourceMapURL);

lib/internal/util/embedding.js

@@ -1,7 +1,8 @@
 'use strict';
-const { codes: { ERR_UNKNOWN_BUILTIN_MODULE } } = require('internal/errors');
 const { BuiltinModule: { normalizeRequirableId } } = require('internal/bootstrap/realm');
 const { Module, wrapSafe } = require('internal/modules/cjs/loader');
+const { codes: { ERR_UNKNOWN_BUILTIN_MODULE } } = require('internal/errors');
+const { getCodeCache, getCodePath, isSea } = internalBinding('sea');
 
 // This is roughly the same as:
 //
@@ -15,7 +16,11 @@ const { Module, wrapSafe } = require('internal/modules/cjs/loader');
 
 function embedderRunCjs(contents) {
   const filename = process.execPath;
-  const compiledWrapper = wrapSafe(filename, contents);
+  const compiledWrapper = wrapSafe(
+    isSea() ? getCodePath() : filename,
+    contents,
+    undefined,
+    getCodeCache());
 
   const customModule = new Module(filename, null);
   customModule.filename = filename;

src/json_parser.cc

@@ -4,34 +4,15 @@
 #include "util-inl.h"
 
 namespace node {
-using v8::ArrayBuffer;
 using v8::Context;
 using v8::Isolate;
 using v8::Local;
 using v8::Object;
 using v8::String;
 using v8::Value;
 
-static Isolate* NewIsolate(v8::ArrayBuffer::Allocator* allocator) {
-  Isolate* isolate = Isolate::Allocate();
-  CHECK_NOT_NULL(isolate);
-  per_process::v8_platform.Platform()->RegisterIsolate(isolate,
-                                                       uv_default_loop());
-  Isolate::CreateParams params;
-  params.array_buffer_allocator = allocator;
-  Isolate::Initialize(isolate, params);
-  return isolate;
-}
-
-void JSONParser::FreeIsolate(Isolate* isolate) {
-  per_process::v8_platform.Platform()->UnregisterIsolate(isolate);
-  isolate->Dispose();
-}
-
 JSONParser::JSONParser()
-    : allocator_(ArrayBuffer::Allocator::NewDefaultAllocator()),
-      isolate_(NewIsolate(allocator_.get())),
-      handle_scope_(isolate_.get()),
+    : handle_scope_(isolate_.get()),
       context_(isolate_.get(), Context::New(isolate_.get())),
       context_scope_(context_.Get(isolate_.get())) {}
 

src/json_parser.h

@@ -24,9 +24,7 @@ class JSONParser {
  private:
   // We might want a lighter-weight JSON parser for this use case. But for now
   // using V8 is good enough.
-  static void FreeIsolate(v8::Isolate* isolate);
-  std::unique_ptr<v8::ArrayBuffer::Allocator> allocator_;
-  DeleteFnPtr<v8::Isolate, FreeIsolate> isolate_;
+  RAIIIsolate isolate_;
   v8::HandleScope handle_scope_;
   v8::Global<v8::Context> context_;
   v8::Context::Scope context_scope_;

src/node_contextify.cc

@@ -935,6 +935,22 @@ Maybe<bool> StoreCodeCacheResult(
   return Just(true);
 }
 
+// TODO(RaisinTen): Reuse in ContextifyContext::CompileFunction().
+MaybeLocal<Function> CompileFunction(Local<Context> context,
+                                     Local<String> filename,
+                                     Local<String> content,
+                                     std::vector<Local<String>>* parameters) {
+  ScriptOrigin script_origin(context->GetIsolate(), filename, 0, 0, true);
+  ScriptCompiler::Source script_source(content, script_origin);
+
+  return ScriptCompiler::CompileFunction(context,
+                                         &script_source,
+                                         parameters->size(),
+                                         parameters->data(),
+                                         0,
+                                         nullptr);
+}
+
 bool ContextifyScript::InstanceOf(Environment* env,
                                   const Local<Value>& value) {
   return !value.IsEmpty() &&

src/node_contextify.h

@@ -210,6 +210,12 @@ v8::Maybe<bool> StoreCodeCacheResult(
     bool produce_cached_data,
     std::unique_ptr<v8::ScriptCompiler::CachedData> new_cached_data);
 
+v8::MaybeLocal<v8::Function> CompileFunction(
+    v8::Local<v8::Context> context,
+    v8::Local<v8::String> filename,
+    v8::Local<v8::String> content,
+    std::vector<v8::Local<v8::String>>* parameters);
+
 }  // namespace contextify
 }  // namespace node