bootstrap: put is_building_snapshot state in IsolateData and introduce ERR_NOT_SUPPORTED_IN_SNAPSHOT

doc/api/errors.md

@@ -2414,6 +2414,13 @@ error indicates that the idle loop has failed to stop.
 An attempt was made to use operations that can only be used when building
 V8 startup snapshot even though Node.js isn't building one.
 
+<a id="ERR_NOT_SUPPORTED_IN_SNAPSHOT"></a>
+
+### `ERR_NOT_SUPPORTED_IN_SNAPSHOT`
+
+An attempt was made to perform operations that are not supported when
+building a startup snapshot.
+
 <a id="ERR_NO_CRYPTO"></a>
 
 ### `ERR_NO_CRYPTO`

lib/internal/errors.js

@@ -1464,6 +1464,8 @@ E('ERR_NETWORK_IMPORT_DISALLOWED',
   "import of '%s' by %s is not supported: %s", Error);
 E('ERR_NOT_BUILDING_SNAPSHOT',
   'Operation cannot be invoked when not building startup snapshot', Error);
+E('ERR_NOT_SUPPORTED_IN_SNAPSHOT',
+  '%s is not supported in startup snapshot', Error);
 E('ERR_NO_CRYPTO',
   'Node.js is not compiled with OpenSSL crypto support', Error);
 E('ERR_NO_ICU',

lib/internal/v8/startup_snapshot.js

@@ -6,6 +6,7 @@ const {
 const {
   codes: {
     ERR_NOT_BUILDING_SNAPSHOT,
+    ERR_NOT_SUPPORTED_IN_SNAPSHOT,
     ERR_DUPLICATE_STARTUP_SNAPSHOT_MAIN_FUNCTION,
   },
 } = require('internal/errors');
@@ -14,11 +15,11 @@ const {
   setSerializeCallback,
   setDeserializeCallback,
   setDeserializeMainFunction: _setDeserializeMainFunction,
+  isBuildingSnapshotBuffer,
 } = internalBinding('mksnapshot');
 
 function isBuildingSnapshot() {
-  // For now this is the only way to build a snapshot.
-  return require('internal/options').getOptionValue('--build-snapshot');
+  return isBuildingSnapshotBuffer[0];
 }
 
 function throwIfNotBuildingSnapshot() {
@@ -27,6 +28,12 @@ function throwIfNotBuildingSnapshot() {
   }
 }
 
+function throwIfBuildingSnapshot(reason) {
+  if (isBuildingSnapshot()) {
+    throw new ERR_NOT_SUPPORTED_IN_SNAPSHOT(reason);
+  }
+}
+
 const deserializeCallbacks = [];
 let deserializeCallbackIsSet = false;
 function runDeserializeCallbacks() {
@@ -102,6 +109,7 @@ function setDeserializeMainFunction(callback, data) {
 module.exports = {
   initializeCallbacks,
   runDeserializeCallbacks,
+  throwIfBuildingSnapshot,
   // Exposed to require('v8').startupSnapshot
   namespace: {
     addDeserializeCallback,

lib/internal/worker.js

@@ -60,7 +60,9 @@ const { deserializeError } = require('internal/error_serdes');
 const { fileURLToPath, isURL, pathToFileURL } = require('internal/url');
 const { kEmptyObject } = require('internal/util');
 const { validateArray, validateString } = require('internal/validators');
-
+const {
+  throwIfBuildingSnapshot,
+} = require('internal/v8/startup_snapshot');
 const {
   ownsProcessState,
   isMainThread,
@@ -129,6 +131,7 @@ function assignEnvironmentData(data) {
 
 class Worker extends EventEmitter {
   constructor(filename, options = kEmptyObject) {
+    throwIfBuildingSnapshot('Creating workers');
     super();
     const isInternal = arguments[2] === kIsInternal;
     debug(

src/api/embed_helpers.cc

@@ -142,8 +142,8 @@ CommonEnvironmentSetup::CommonEnvironmentSetup(
 
     impl_->isolate_data.reset(CreateIsolateData(
         isolate, loop, platform, impl_->allocator.get(), snapshot_data));
-    impl_->isolate_data->options()->build_snapshot =
-        impl_->snapshot_creator.has_value();
+    impl_->isolate_data->set_is_building_snapshot(
+        impl_->snapshot_creator.has_value());
 
     if (snapshot_data) {
       impl_->env.reset(make_env(this));

src/base_object_types.h

@@ -12,6 +12,7 @@ namespace node {
 #define SERIALIZABLE_BINDING_TYPES(V)                                          \
   V(encoding_binding_data, encoding_binding::BindingData)                      \
   V(fs_binding_data, fs::BindingData)                                          \
+  V(mksnapshot_binding_data, mksnapshot::BindingData)                          \
   V(v8_binding_data, v8_utils::BindingData)                                    \
   V(blob_binding_data, BlobBindingData)                                        \
   V(process_binding_data, process::BindingData)                                \

src/env.h

@@ -136,6 +136,9 @@ class NODE_EXTERN_PRIVATE IsolateData : public MemoryRetainer {
   void MemoryInfo(MemoryTracker* tracker) const override;
   IsolateDataSerializeInfo Serialize(v8::SnapshotCreator* creator);
 
+  bool is_building_snapshot() const { return is_building_snapshot_; }
+  void set_is_building_snapshot(bool value) { is_building_snapshot_ = value; }
+
   inline uv_loop_t* event_loop() const;
   inline MultiIsolatePlatform* platform() const;
   inline const SnapshotData* snapshot_data() const;
@@ -219,6 +222,7 @@ class NODE_EXTERN_PRIVATE IsolateData : public MemoryRetainer {
   const SnapshotData* snapshot_data_;
   std::shared_ptr<PerIsolateOptions> options_;
   worker::Worker* worker_context_ = nullptr;
+  bool is_building_snapshot_ = false;
 };
 
 struct ContextInfo {

src/node.cc

@@ -283,7 +283,7 @@ MaybeLocal<Value> StartExecution(Environment* env, StartExecutionCallback cb) {
     auto reset_entry_point =
         OnScopeLeave([&]() { env->set_embedder_entry_point({}); });
 
-    const char* entry = env->isolate_data()->options()->build_snapshot
+    const char* entry = env->isolate_data()->is_building_snapshot()
                             ? "internal/main/mksnapshot"
                             : "internal/main/embedding";
 
@@ -311,7 +311,7 @@ MaybeLocal<Value> StartExecution(Environment* env, StartExecutionCallback cb) {
     return StartExecution(env, "internal/main/inspect");
   }
 
-  if (env->isolate_data()->options()->build_snapshot) {
+  if (env->isolate_data()->is_building_snapshot()) {
     return StartExecution(env, "internal/main/mksnapshot");
   }
 

src/node_binding.h

@@ -37,6 +37,7 @@ static_assert(static_cast<int>(NM_F_LINKED) ==
   V(contextify)                                                                \
   V(encoding_binding)                                                          \
   V(fs)                                                                        \
+  V(mksnapshot)                                                                \
   V(timers)                                                                    \
   V(process_methods)                                                           \
   V(performance)                                                               \

src/node_main_instance.cc

@@ -56,6 +56,8 @@ NodeMainInstance::NodeMainInstance(const SnapshotData* snapshot_data,
                         platform,
                         array_buffer_allocator_.get(),
                         snapshot_data->AsEmbedderWrapper().get()));
+  isolate_data_->set_is_building_snapshot(
+      per_process::cli_options->per_isolate->build_snapshot);
 
   isolate_data_->max_young_gen_size =
       isolate_params_->constraints.max_young_generation_size_in_bytes();

src/node_snapshotable.cc

@@ -3,6 +3,7 @@
 #include <iostream>
 #include <sstream>
 #include <vector>
+#include "aliased_buffer-inl.h"
 #include "base_object-inl.h"
 #include "debug_utils-inl.h"
 #include "encoding_binding.h"
@@ -33,6 +34,7 @@ namespace node {
 using v8::Context;
 using v8::Function;
 using v8::FunctionCallbackInfo;
+using v8::FunctionTemplate;
 using v8::HandleScope;
 using v8::Isolate;
 using v8::Local;
@@ -1498,8 +1500,6 @@ void SerializeSnapshotableObjects(Realm* realm,
   });
 }
 
-namespace mksnapshot {
-
 // NB: This is also used by the regular embedding codepath.
 void GetEmbedderEntryFunction(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
@@ -1572,16 +1572,89 @@ void SetDeserializeMainFunction(const FunctionCallbackInfo<Value>& args) {
   env->set_snapshot_deserialize_main(args[0].As<Function>());
 }
 
-void Initialize(Local<Object> target,
-                Local<Value> unused,
-                Local<Context> context,
-                void* priv) {
+namespace mksnapshot {
+
+BindingData::BindingData(Realm* realm,
+                         v8::Local<v8::Object> object,
+                         InternalFieldInfo* info)
+    : SnapshotableObject(realm, object, type_int),
+      is_building_snapshot_buffer_(
+          realm->isolate(),
+          1,
+          MAYBE_FIELD_PTR(info, is_building_snapshot_buffer)) {
+  if (info == nullptr) {
+    object
+        ->Set(
+            realm->context(),
+            FIXED_ONE_BYTE_STRING(realm->isolate(), "isBuildingSnapshotBuffer"),
+            is_building_snapshot_buffer_.GetJSArray())
+        .Check();
+  } else {
+    is_building_snapshot_buffer_.Deserialize(realm->context());
+  }
+  // Reset the status according to the current state of the realm.
+  bool is_building_snapshot = realm->isolate_data()->is_building_snapshot();
+  DCHECK_IMPLIES(is_building_snapshot,
+                 realm->isolate_data()->snapshot_data() == nullptr);
+  is_building_snapshot_buffer_[0] = is_building_snapshot ? 1 : 0;
+  is_building_snapshot_buffer_.MakeWeak();
+}
+
+bool BindingData::PrepareForSerialization(Local<Context> context,
+                                          v8::SnapshotCreator* creator) {
+  DCHECK_NULL(internal_field_info_);
+  internal_field_info_ = InternalFieldInfoBase::New<InternalFieldInfo>(type());
+  internal_field_info_->is_building_snapshot_buffer =
+      is_building_snapshot_buffer_.Serialize(context, creator);
+  // Return true because we need to maintain the reference to the binding from
+  // JS land.
+  return true;
+}
+
+InternalFieldInfoBase* BindingData::Serialize(int index) {
+  DCHECK_EQ(index, BaseObject::kEmbedderType);
+  InternalFieldInfo* info = internal_field_info_;
+  internal_field_info_ = nullptr;
+  return info;
+}
+
+void BindingData::Deserialize(Local<Context> context,
+                              Local<Object> holder,
+                              int index,
+                              InternalFieldInfoBase* info) {
+  DCHECK_EQ(index, BaseObject::kEmbedderType);
+  v8::HandleScope scope(context->GetIsolate());
+  Realm* realm = Realm::GetCurrent(context);
+  // Recreate the buffer in the constructor.
+  InternalFieldInfo* casted_info = static_cast<InternalFieldInfo*>(info);
+  BindingData* binding =
+      realm->AddBindingData<BindingData>(context, holder, casted_info);
+  CHECK_NOT_NULL(binding);
+}
+
+void BindingData::MemoryInfo(MemoryTracker* tracker) const {
+  tracker->TrackField("is_building_snapshot_buffer",
+                      is_building_snapshot_buffer_);
+}
+
+void CreatePerContextProperties(Local<Object> target,
+                                Local<Value> unused,
+                                Local<Context> context,
+                                void* priv) {
+  Realm* realm = Realm::GetCurrent(context);
+  realm->AddBindingData<BindingData>(context, target);
+}
+
+void CreatePerIsolateProperties(IsolateData* isolate_data,
+                                Local<FunctionTemplate> ctor) {
+  Isolate* isolate = isolate_data->isolate();
+  Local<ObjectTemplate> target = ctor->PrototypeTemplate();
   SetMethod(
-      context, target, "getEmbedderEntryFunction", GetEmbedderEntryFunction);
-  SetMethod(context, target, "compileSerializeMain", CompileSerializeMain);
-  SetMethod(context, target, "setSerializeCallback", SetSerializeCallback);
-  SetMethod(context, target, "setDeserializeCallback", SetDeserializeCallback);
-  SetMethod(context,
+      isolate, target, "getEmbedderEntryFunction", GetEmbedderEntryFunction);
+  SetMethod(isolate, target, "compileSerializeMain", CompileSerializeMain);
+  SetMethod(isolate, target, "setSerializeCallback", SetSerializeCallback);
+  SetMethod(isolate, target, "setDeserializeCallback", SetDeserializeCallback);
+  SetMethod(isolate,
             target,
             "setDeserializeMainFunction",
             SetDeserializeMainFunction);
@@ -1595,8 +1668,12 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(SetDeserializeMainFunction);
 }
 }  // namespace mksnapshot
+
 }  // namespace node
 
-NODE_BINDING_CONTEXT_AWARE_INTERNAL(mksnapshot, node::mksnapshot::Initialize)
+NODE_BINDING_CONTEXT_AWARE_INTERNAL(
+    mksnapshot, node::mksnapshot::CreatePerContextProperties)
+NODE_BINDING_PER_ISOLATE_INIT(mksnapshot,
+                              node::mksnapshot::CreatePerIsolateProperties)
 NODE_BINDING_EXTERNAL_REFERENCE(mksnapshot,
                                 node::mksnapshot::RegisterExternalReferences)

src/node_snapshotable.h

@@ -4,6 +4,7 @@
 
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
+#include "aliased_buffer.h"
 #include "base_object.h"
 #include "util.h"
 
@@ -121,6 +122,31 @@ void DeserializeNodeInternalFields(v8::Local<v8::Object> holder,
 void SerializeSnapshotableObjects(Realm* realm,
                                   v8::SnapshotCreator* creator,
                                   RealmSerializeInfo* info);
+
+namespace mksnapshot {
+class BindingData : public SnapshotableObject {
+ public:
+  struct InternalFieldInfo : public node::InternalFieldInfoBase {
+    AliasedBufferIndex is_building_snapshot_buffer;
+  };
+
+  BindingData(Realm* realm,
+              v8::Local<v8::Object> obj,
+              InternalFieldInfo* info = nullptr);
+  SET_BINDING_ID(mksnapshot_binding_data)
+  SERIALIZABLE_OBJECT_METHODS()
+
+  void MemoryInfo(MemoryTracker* tracker) const override;
+  SET_SELF_SIZE(BindingData)
+  SET_MEMORY_INFO_NAME(BindingData)
+
+ private:
+  AliasedUint8Array is_building_snapshot_buffer_;
+  InternalFieldInfo* internal_field_info_ = nullptr;
+};
+
+}  // namespace mksnapshot
+
 }  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

src/node_worker.cc

@@ -186,6 +186,7 @@ class WorkerThreadData {
                             allocator.get(),
                             w->snapshot_data()->AsEmbedderWrapper().get()));
       CHECK(isolate_data_);
+      CHECK(!isolate_data_->is_building_snapshot());
       if (w_->per_isolate_opts_)
         isolate_data_->set_options(std::move(w_->per_isolate_opts_));
       isolate_data_->set_worker_context(w_);
@@ -481,6 +482,7 @@ void Worker::New(const FunctionCallbackInfo<Value>& args) {
     THROW_ERR_MISSING_PLATFORM_FOR_WORKER(env);
     return;
   }
+  CHECK(!env->isolate_data()->is_building_snapshot());
 
   std::string url;
   std::string name;

test/fixtures/snapshot/worker.js

@@ -0,0 +1,5 @@
+'use strict';
+
+const { Worker } = require('worker_threads');
+
+new Worker('1', { eval: true });

test/parallel/test-snapshot-worker.js

@@ -0,0 +1,34 @@
+'use strict';
+
+// This tests snapshot JS API using the example in the docs.
+
+require('../common');
+const assert = require('assert');
+const { spawnSync } = require('child_process');
+const tmpdir = require('../common/tmpdir');
+const fixtures = require('../common/fixtures');
+const path = require('path');
+const fs = require('fs');
+
+tmpdir.refresh();
+const blobPath = path.join(tmpdir.path, 'snapshot.blob');
+const entry = fixtures.path('snapshot', 'worker.js');
+{
+  const child = spawnSync(process.execPath, [
+    '--snapshot-blob',
+    blobPath,
+    '--build-snapshot',
+    entry,
+  ], {
+    cwd: tmpdir.path
+  });
+  const stderr = child.stderr.toString();
+  assert.match(
+    stderr,
+    /Error: Creating workers is not supported in startup snapshot/);
+  assert.match(
+    stderr,
+    /ERR_NOT_SUPPORTED_IN_SNAPSHOT/);
+  assert.strictEqual(child.status, 1);
+  assert(!fs.existsSync(blobPath));
+}