From b810e6703968ea3cd82262aa9acc57fabc894cd1 Mon Sep 17 00:00:00 2001
From: Gus Caplan <me@gus.host>
Date: Thu, 9 Jan 2020 08:34:55 -0800
Subject: [PATCH] vm: add code cache support for SourceTextModule

PR-URL: https://github.com/nodejs/node/pull/31278
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
---
 doc/api/errors.md                           | 10 +++
 doc/api/vm.md                               | 26 ++++++++
 lib/internal/errors.js                      |  2 +
 lib/internal/vm/module.js                   | 29 +++++++-
 src/module_wrap.cc                          | 73 ++++++++++++++++++---
 src/module_wrap.h                           |  1 +
 src/node_errors.h                           |  1 +
 test/parallel/test-vm-module-cached-data.js | 30 +++++++++
 8 files changed, 162 insertions(+), 10 deletions(-)
 create mode 100644 test/parallel/test-vm-module-cached-data.js

diff --git a/doc/api/errors.md b/doc/api/errors.md
index c5041c796be011..4d9651be8ddd2a 100644
--- a/doc/api/errors.md
+++ b/doc/api/errors.md
@@ -1988,6 +1988,16 @@ the following reasons:
 * It is being linked (`linkingStatus` is `'linking'`)
 * Linking has failed for this module (`linkingStatus` is `'errored'`)
 
+<a id="ERR_VM_MODULE_CACHED_DATA_REJECTED"></a>
+### `ERR_VM_MODULE_CACHED_DATA_REJECTED`
+
+The `cachedData` option passed to a module constructor is invalid.
+
+<a id="ERR_VM_MODULE_CANNOT_CREATE_CACHED_DATA"></a>
+### `ERR_VM_MODULE_CANNOT_CREATE_CACHED_DATA`
+
+Cached data cannot be created for modules which have already been evaluated.
+
 <a id="ERR_VM_MODULE_DIFFERENT_CONTEXT"></a>
 ### `ERR_VM_MODULE_DIFFERENT_CONTEXT`
 
diff --git a/doc/api/vm.md b/doc/api/vm.md
index 9e832ac8bb8606..57109f143a0f4d 100644
--- a/doc/api/vm.md
+++ b/doc/api/vm.md
@@ -566,6 +566,10 @@ defined in the ECMAScript specification.
   * `identifier` {string} String used in stack traces.
     **Default:** `'vm:module(i)'` where `i` is a context-specific ascending
     index.
+  * `cachedData` {Buffer|TypedArray|DataView} Provides an optional `Buffer` or
+    `TypedArray`, or `DataView` with V8's code cache data for the supplied
+     source. The `code` must be the same as the module from which this
+     `cachedData` was created.
   * `context` {Object} The [contextified][] object as returned by the
     `vm.createContext()` method, to compile and evaluate this `Module` in.
   * `lineOffset` {integer} Specifies the line number offset that is displayed
@@ -621,6 +625,28 @@ const contextifiedObject = vm.createContext({ secret: 42 });
 })();
 ```
 
+### `sourceTextModule.createCachedData()`
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {Buffer}
+
+Creates a code cache that can be used with the SourceTextModule constructor's
+`cachedData` option. Returns a Buffer. This method may be called any number
+of times before the module has been evaluated.
+
+```js
+// Create an initial module
+const module = new vm.SourceTextModule('const a = 1;');
+
+// Create cached data from this module
+const cachedData = module.createCachedData();
+
+// Create a new module using the cached data. The code must be the same.
+const module2 = new vm.SourceTextModule('const a = 1;', { cachedData });
+```
+
 ## Class: `vm.SyntheticModule`
 <!-- YAML
 added: v13.0.0
diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index ed03b8d47a53a7..15d04db3132271 100644
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -1351,6 +1351,8 @@ E('ERR_VALID_PERFORMANCE_ENTRY_TYPE',
 E('ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING',
   'A dynamic import callback was not specified.', TypeError);
 E('ERR_VM_MODULE_ALREADY_LINKED', 'Module has already been linked', Error);
+E('ERR_VM_MODULE_CANNOT_CREATE_CACHED_DATA',
+  'Cached data cannot be created for a module which has been evaluated', Error);
 E('ERR_VM_MODULE_DIFFERENT_CONTEXT',
   'Linked modules must use the same context', Error);
 E('ERR_VM_MODULE_LINKING_ERRORED',
diff --git a/lib/internal/vm/module.js b/lib/internal/vm/module.js
index d12362184a5051..ed0dedd1e31b4f 100644
--- a/lib/internal/vm/module.js
+++ b/lib/internal/vm/module.js
@@ -11,7 +11,10 @@ const {
 } = primordials;
 
 const { isContext } = internalBinding('contextify');
-const { isModuleNamespaceObject } = require('internal/util/types');
+const {
+  isModuleNamespaceObject,
+  isArrayBufferView,
+} = require('internal/util/types');
 const {
   getConstructorOf,
   customInspectSymbol,
@@ -21,6 +24,7 @@ const {
   ERR_INVALID_ARG_TYPE,
   ERR_VM_MODULE_ALREADY_LINKED,
   ERR_VM_MODULE_DIFFERENT_CONTEXT,
+  ERR_VM_MODULE_CANNOT_CREATE_CACHED_DATA,
   ERR_VM_MODULE_LINKING_ERRORED,
   ERR_VM_MODULE_NOT_MODULE,
   ERR_VM_MODULE_STATUS,
@@ -107,7 +111,8 @@ class Module {
 
     if (sourceText !== undefined) {
       this[kWrap] = new ModuleWrap(identifier, context, sourceText,
-                                   options.lineOffset, options.columnOffset);
+                                   options.lineOffset, options.columnOffset,
+                                   options.cachedData);
 
       binding.callbackMap.set(this[kWrap], {
         initializeImportMeta: options.initializeImportMeta,
@@ -253,6 +258,7 @@ class SourceTextModule extends Module {
       importModuleDynamically,
       context,
       identifier,
+      cachedData,
     } = options;
 
     validateInt32(lineOffset, 'options.lineOffset');
@@ -271,12 +277,21 @@ class SourceTextModule extends Module {
         importModuleDynamically);
     }
 
+    if (cachedData !== undefined && !isArrayBufferView(cachedData)) {
+      throw new ERR_INVALID_ARG_TYPE(
+        'options.cachedData',
+        ['Buffer', 'TypedArray', 'DataView'],
+        cachedData
+      );
+    }
+
     super({
       sourceText,
       context,
       identifier,
       lineOffset,
       columnOffset,
+      cachedData,
       initializeImportMeta,
       importModuleDynamically,
     });
@@ -348,6 +363,16 @@ class SourceTextModule extends Module {
     }
     return super.error;
   }
+
+  createCachedData() {
+    const { status } = this;
+    if (status === 'evaluating' ||
+        status === 'evaluated' ||
+        status === 'errored') {
+      throw new ERR_VM_MODULE_CANNOT_CREATE_CACHED_DATA();
+    }
+    return this[kWrap].createCachedData();
+  }
 }
 
 class SyntheticModule extends Module {
diff --git a/src/module_wrap.cc b/src/module_wrap.cc
index ff6f0db651a7df..f06b9d40c33c37 100644
--- a/src/module_wrap.cc
+++ b/src/module_wrap.cc
@@ -2,12 +2,13 @@
 
 #include "env.h"
 #include "memory_tracker-inl.h"
+#include "node_contextify.h"
 #include "node_errors.h"
+#include "node_internals.h"
+#include "node_process.h"
 #include "node_url.h"
-#include "util-inl.h"
-#include "node_contextify.h"
 #include "node_watchdog.h"
-#include "node_process.h"
+#include "util-inl.h"
 
 #include <sys/stat.h>  // S_IFDIR
 
@@ -22,6 +23,7 @@ using node::contextify::ContextifyContext;
 using node::url::URL;
 using node::url::URL_FLAGS_FAILED;
 using v8::Array;
+using v8::ArrayBufferView;
 using v8::Context;
 using v8::Function;
 using v8::FunctionCallbackInfo;
@@ -44,6 +46,7 @@ using v8::Promise;
 using v8::ScriptCompiler;
 using v8::ScriptOrigin;
 using v8::String;
+using v8::UnboundModuleScript;
 using v8::Undefined;
 using v8::Value;
 
@@ -131,7 +134,7 @@ void ModuleWrap::New(const FunctionCallbackInfo<Value>& args) {
     // new ModuleWrap(url, context, exportNames, syntheticExecutionFunction)
     CHECK(args[3]->IsFunction());
   } else {
-    // new ModuleWrap(url, context, source, lineOffset, columOffset)
+    // new ModuleWrap(url, context, source, lineOffset, columOffset, cachedData)
     CHECK(args[2]->IsString());
     CHECK(args[3]->IsNumber());
     line_offset = args[3].As<Integer>();
@@ -167,6 +170,17 @@ void ModuleWrap::New(const FunctionCallbackInfo<Value>& args) {
       module = Module::CreateSyntheticModule(isolate, url, export_names,
         SyntheticModuleEvaluationStepsCallback);
     } else {
+      ScriptCompiler::CachedData* cached_data = nullptr;
+      if (!args[5]->IsUndefined()) {
+        CHECK(args[5]->IsArrayBufferView());
+        Local<ArrayBufferView> cached_data_buf = args[5].As<ArrayBufferView>();
+        uint8_t* data = static_cast<uint8_t*>(
+            cached_data_buf->Buffer()->GetBackingStore()->Data());
+        cached_data =
+            new ScriptCompiler::CachedData(data + cached_data_buf->ByteOffset(),
+                                           cached_data_buf->ByteLength());
+      }
+
       Local<String> source_text = args[2].As<String>();
       ScriptOrigin origin(url,
                           line_offset,                      // line offset
@@ -178,8 +192,15 @@ void ModuleWrap::New(const FunctionCallbackInfo<Value>& args) {
                           False(isolate),                   // is WASM
                           True(isolate),                    // is ES Module
                           host_defined_options);
-      ScriptCompiler::Source source(source_text, origin);
-      if (!ScriptCompiler::CompileModule(isolate, &source).ToLocal(&module)) {
+      ScriptCompiler::Source source(source_text, origin, cached_data);
+      ScriptCompiler::CompileOptions options;
+      if (source.GetCachedData() == nullptr) {
+        options = ScriptCompiler::kNoCompileOptions;
+      } else {
+        options = ScriptCompiler::kConsumeCodeCache;
+      }
+      if (!ScriptCompiler::CompileModule(isolate, &source, options)
+               .ToLocal(&module)) {
         if (try_catch.HasCaught() && !try_catch.HasTerminated()) {
           CHECK(!try_catch.Message().IsEmpty());
           CHECK(!try_catch.Exception().IsEmpty());
@@ -189,6 +210,13 @@ void ModuleWrap::New(const FunctionCallbackInfo<Value>& args) {
         }
         return;
       }
+      if (options == ScriptCompiler::kConsumeCodeCache &&
+          source.GetCachedData()->rejected) {
+        THROW_ERR_VM_MODULE_CACHED_DATA_REJECTED(
+            env, "cachedData buffer was rejected");
+        try_catch.ReThrow();
+        return;
+      }
     }
   }
 
@@ -1507,8 +1535,7 @@ MaybeLocal<Value> ModuleWrap::SyntheticModuleEvaluationStepsCallback(
   return ret;
 }
 
-void ModuleWrap::SetSyntheticExport(
-      const v8::FunctionCallbackInfo<v8::Value>& args) {
+void ModuleWrap::SetSyntheticExport(const FunctionCallbackInfo<Value>& args) {
   Isolate* isolate = args.GetIsolate();
   Local<Object> that = args.This();
 
@@ -1528,6 +1555,35 @@ void ModuleWrap::SetSyntheticExport(
   USE(module->SetSyntheticModuleExport(isolate, export_name, export_value));
 }
 
+void ModuleWrap::CreateCachedData(const FunctionCallbackInfo<Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  Local<Object> that = args.This();
+
+  ModuleWrap* obj;
+  ASSIGN_OR_RETURN_UNWRAP(&obj, that);
+
+  CHECK(!obj->synthetic_);
+
+  Local<Module> module = obj->module_.Get(isolate);
+
+  CHECK_LT(module->GetStatus(), v8::Module::Status::kEvaluating);
+
+  Local<UnboundModuleScript> unbound_module_script =
+      module->GetUnboundModuleScript();
+  std::unique_ptr<ScriptCompiler::CachedData> cached_data(
+      ScriptCompiler::CreateCodeCache(unbound_module_script));
+  Environment* env = Environment::GetCurrent(args);
+  if (!cached_data) {
+    args.GetReturnValue().Set(Buffer::New(env, 0).ToLocalChecked());
+  } else {
+    MaybeLocal<Object> buf =
+        Buffer::Copy(env,
+                     reinterpret_cast<const char*>(cached_data->data),
+                     cached_data->length);
+    args.GetReturnValue().Set(buf.ToLocalChecked());
+  }
+}
+
 void ModuleWrap::Initialize(Local<Object> target,
                             Local<Value> unused,
                             Local<Context> context,
@@ -1543,6 +1599,7 @@ void ModuleWrap::Initialize(Local<Object> target,
   env->SetProtoMethod(tpl, "instantiate", Instantiate);
   env->SetProtoMethod(tpl, "evaluate", Evaluate);
   env->SetProtoMethod(tpl, "setExport", SetSyntheticExport);
+  env->SetProtoMethodNoSideEffect(tpl, "createCachedData", CreateCachedData);
   env->SetProtoMethodNoSideEffect(tpl, "getNamespace", GetNamespace);
   env->SetProtoMethodNoSideEffect(tpl, "getStatus", GetStatus);
   env->SetProtoMethodNoSideEffect(tpl, "getError", GetError);
diff --git a/src/module_wrap.h b/src/module_wrap.h
index bee4000d168062..8937431022c0e1 100644
--- a/src/module_wrap.h
+++ b/src/module_wrap.h
@@ -75,6 +75,7 @@ class ModuleWrap : public BaseObject {
       v8::Local<v8::Context> context, v8::Local<v8::Module> module);
   static void SetSyntheticExport(
       const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void CreateCachedData(const v8::FunctionCallbackInfo<v8::Value>& args);
 
   static v8::MaybeLocal<v8::Module> ResolveCallback(
       v8::Local<v8::Context> context,
diff --git a/src/node_errors.h b/src/node_errors.h
index 74413e7456a356..e554d5fd9250a3 100644
--- a/src/node_errors.h
+++ b/src/node_errors.h
@@ -59,6 +59,7 @@ void PrintErrorString(const char* format, ...);
   V(ERR_TLS_INVALID_PROTOCOL_METHOD, TypeError)                              \
   V(ERR_TRANSFERRING_EXTERNALIZED_SHAREDARRAYBUFFER, TypeError)              \
   V(ERR_TLS_PSK_SET_IDENTIY_HINT_FAILED, Error)                              \
+  V(ERR_VM_MODULE_CACHED_DATA_REJECTED, Error)                               \
 
 #define V(code, type)                                                         \
   inline v8::Local<v8::Value> code(v8::Isolate* isolate,                      \
diff --git a/test/parallel/test-vm-module-cached-data.js b/test/parallel/test-vm-module-cached-data.js
new file mode 100644
index 00000000000000..f91d9e62688dc5
--- /dev/null
+++ b/test/parallel/test-vm-module-cached-data.js
@@ -0,0 +1,30 @@
+'use strict';
+
+// Flags: --experimental-vm-modules
+
+require('../common');
+
+const assert = require('assert');
+const { SourceTextModule } = require('vm');
+
+{
+  const m = new SourceTextModule('const a = 1');
+  const cachedData = m.createCachedData();
+
+  new SourceTextModule('const a = 1', { cachedData });
+
+  assert.throws(() => {
+    new SourceTextModule('differentSource', { cachedData });
+  }, {
+    code: 'ERR_VM_MODULE_CACHED_DATA_REJECTED',
+  });
+}
+
+assert.rejects(async () => {
+  const m = new SourceTextModule('const a = 1');
+  await m.link(() => {});
+  m.evaluate();
+  m.createCachedData();
+}, {
+  code: 'ERR_VM_MODULE_CANNOT_CREATE_CACHED_DATA',
+});