src: allow creating NodeMainInstance that does not own the isolate

Allows instantiating a NodeMainInstance with an isolate
whose initialization and disposal are controlled by the caller.

PR-URL: https://github.com/nodejs/node/pull/27321
Refs: https://github.com/nodejs/node/issues/17058
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

5 files changed, 131 insertions, 31 deletions

diff --git a/src/api/environment.cc b/src/api/environment.cc
index 0543e0323d..9a29ad1e5e 100644
--- a/src/api/environment.cc
+++ b/src/api/environment.cc
@@ -183,17 +183,33 @@ void SetIsolateCreateParamsForNode(Isolate::CreateParams* params) {
 #endif
 }
 
+void SetIsolateUpForNode(v8::Isolate* isolate, IsolateSettingCategories cat) {
+  switch (cat) {
+    case IsolateSettingCategories::kErrorHandlers:
+      isolate->AddMessageListenerWithErrorLevel(
+          OnMessage,
+          Isolate::MessageErrorLevel::kMessageError |
+              Isolate::MessageErrorLevel::kMessageWarning);
+      isolate->SetAbortOnUncaughtExceptionCallback(
+          ShouldAbortOnUncaughtException);
+      isolate->SetFatalErrorHandler(OnFatalError);
+      break;
+    case IsolateSettingCategories::kMisc:
+      isolate->SetMicrotasksPolicy(MicrotasksPolicy::kExplicit);
+      isolate->SetAllowWasmCodeGenerationCallback(
+          AllowWasmCodeGenerationCallback);
+      isolate->SetPromiseRejectCallback(task_queue::PromiseRejectCallback);
+      v8::CpuProfiler::UseDetailedSourcePositionsForProfiling(isolate);
+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
 void SetIsolateUpForNode(v8::Isolate* isolate) {
-  isolate->AddMessageListenerWithErrorLevel(
-      OnMessage,
-      Isolate::MessageErrorLevel::kMessageError |
-          Isolate::MessageErrorLevel::kMessageWarning);
-  isolate->SetAbortOnUncaughtExceptionCallback(ShouldAbortOnUncaughtException);
-  isolate->SetMicrotasksPolicy(MicrotasksPolicy::kExplicit);
-  isolate->SetFatalErrorHandler(OnFatalError);
-  isolate->SetAllowWasmCodeGenerationCallback(AllowWasmCodeGenerationCallback);
-  isolate->SetPromiseRejectCallback(task_queue::PromiseRejectCallback);
-  v8::CpuProfiler::UseDetailedSourcePositionsForProfiling(isolate);
+  SetIsolateUpForNode(isolate, IsolateSettingCategories::kErrorHandlers);
+  SetIsolateUpForNode(isolate, IsolateSettingCategories::kMisc);
 }
 
 Isolate* NewIsolate(ArrayBufferAllocator* allocator, uv_loop_t* event_loop) {
diff --git a/src/node.cc b/src/node.cc
index 061d6bb424..9e969d33dc 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -886,8 +886,12 @@ int Start(int argc, char** argv) {
   }
 
   {
-    NodeMainInstance main_instance(
-        uv_default_loop(), result.args, result.exec_args);
+    Isolate::CreateParams params;
+    NodeMainInstance main_instance(&params,
+                                   uv_default_loop(),
+                                   per_process::v8_platform.Platform(),
+                                   result.args,
+                                   result.exec_args);
     result.exit_code = main_instance.Run();
   }
 
diff --git a/src/node_internals.h b/src/node_internals.h
index 3fc6ea0736..fc924e3e16 100644
--- a/src/node_internals.h
+++ b/src/node_internals.h
@@ -319,6 +319,9 @@ struct InitializationResult {
 };
 InitializationResult InitializeOncePerProcess(int argc, char** argv);
 void TearDownOncePerProcess();
+enum class IsolateSettingCategories { kErrorHandlers, kMisc };
+void SetIsolateUpForNode(v8::Isolate* isolate, IsolateSettingCategories cat);
+void SetIsolateCreateParamsForNode(v8::Isolate::CreateParams* params);
 
 #if HAVE_INSPECTOR
 namespace profiler {
diff --git a/src/node_main_instance.cc b/src/node_main_instance.cc
index 6ef992d006..4b05149b23 100644
--- a/src/node_main_instance.cc
+++ b/src/node_main_instance.cc
@@ -12,30 +12,70 @@ using v8::Local;
 using v8::Locker;
 using v8::SealHandleScope;
 
-NodeMainInstance::NodeMainInstance(uv_loop_t* event_loop,
+NodeMainInstance::NodeMainInstance(Isolate* isolate,
+                                   uv_loop_t* event_loop,
+                                   MultiIsolatePlatform* platform,
+                                   const std::vector<std::string>& args,
+                                   const std::vector<std::string>& exec_args)
+    : args_(args),
+      exec_args_(exec_args),
+      array_buffer_allocator_(nullptr),
+      isolate_(isolate),
+      platform_(platform),
+      isolate_data_(nullptr),
+      owns_isolate_(false) {
+  isolate_data_.reset(new IsolateData(isolate_, event_loop, platform, nullptr));
+  SetIsolateUpForNode(isolate_, IsolateSettingCategories::kMisc);
+}
+
+NodeMainInstance* NodeMainInstance::Create(
+    Isolate* isolate,
+    uv_loop_t* event_loop,
+    MultiIsolatePlatform* platform,
+    const std::vector<std::string>& args,
+    const std::vector<std::string>& exec_args) {
+  return new NodeMainInstance(isolate, event_loop, platform, args, exec_args);
+}
+
+NodeMainInstance::NodeMainInstance(Isolate::CreateParams* params,
+                                   uv_loop_t* event_loop,
+                                   MultiIsolatePlatform* platform,
                                    const std::vector<std::string>& args,
                                    const std::vector<std::string>& exec_args)
     : args_(args),
       exec_args_(exec_args),
       array_buffer_allocator_(ArrayBufferAllocator::Create()),
       isolate_(nullptr),
-      isolate_data_(nullptr) {
-  // TODO(joyeecheung): when we implement snapshot integration this needs to
-  // set params.external_references.
-  Isolate::CreateParams params;
-  params.array_buffer_allocator = array_buffer_allocator_.get();
-  isolate_ =
-      NewIsolate(&params, event_loop, per_process::v8_platform.Platform());
+      platform_(platform),
+      isolate_data_(nullptr),
+      owns_isolate_(true) {
+  params->array_buffer_allocator = array_buffer_allocator_.get();
+  isolate_ = Isolate::Allocate();
   CHECK_NOT_NULL(isolate_);
-  isolate_data_.reset(CreateIsolateData(isolate_,
-                                        event_loop,
-                                        per_process::v8_platform.Platform(),
-                                        array_buffer_allocator_.get()));
+  // Register the isolate on the platform before the isolate gets initialized,
+  // so that the isolate can access the platform during initialization.
+  platform->RegisterIsolate(isolate_, event_loop);
+  SetIsolateCreateParamsForNode(params);
+  Isolate::Initialize(isolate_, *params);
+
+  isolate_data_.reset(new IsolateData(
+      isolate_, event_loop, platform, array_buffer_allocator_.get()));
+  SetIsolateUpForNode(isolate_, IsolateSettingCategories::kMisc);
+  SetIsolateUpForNode(isolate_, IsolateSettingCategories::kErrorHandlers);
+}
+
+void NodeMainInstance::Dispose() {
+  CHECK(!owns_isolate_);
+  platform_->DrainTasks(isolate_);
+  delete this;
 }
 
 NodeMainInstance::~NodeMainInstance() {
+  if (!owns_isolate_) {
+    return;
+  }
   isolate_->Dispose();
-  per_process::v8_platform.Platform()->UnregisterIsolate(isolate_);
+  platform_->UnregisterIsolate(isolate_);
 }
 
 int NodeMainInstance::Run() {
@@ -120,6 +160,7 @@ std::unique_ptr<Environment> NodeMainInstance::CreateMainEnvironment(
   }
 
   Local<Context> context = NewContext(isolate_);
+  CHECK(!context.IsEmpty());
   Context::Scope context_scope(context);
 
   std::unique_ptr<Environment> env = std::make_unique<Environment>(
diff --git a/src/node_main_instance.h b/src/node_main_instance.h
index f140edcfd7..0a8be137a0 100644
--- a/src/node_main_instance.h
+++ b/src/node_main_instance.h
@@ -3,6 +3,7 @@
 
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
+#include <cstddef>
 #include "node.h"
 #include "util.h"
 #include "uv.h"
@@ -14,12 +15,35 @@ namespace node {
 // We may be able to create an abstract class to reuse some of the routines.
 class NodeMainInstance {
  public:
-  NodeMainInstance(const NodeMainInstance&) = delete;
-  NodeMainInstance& operator=(const NodeMainInstance&) = delete;
-  NodeMainInstance(NodeMainInstance&&) = delete;
-  NodeMainInstance& operator=(NodeMainInstance&&) = delete;
+  // To create a main instance that does not own the isoalte,
+  // The caller needs to do:
+  //
+  //   Isolate* isolate = Isolate::Allocate();
+  //   platform->RegisterIsolate(isolate, loop);
+  //   isolate->Initialize(...);
+  //   isolate->Enter();
+  //   NodeMainInstance* main_instance =
+  //       NodeMainInstance::Create(isolate, loop, args, exec_args);
+  //
+  // When tearing it down:
+  //
+  //   main_instance->Cleanup();  // While the isolate is entered
+  //   isolate->Exit();
+  //   isolate->Dispose();
+  //   platform->UnregisterIsolate(isolate);
+  //
+  // After calling Dispose() the main_instance is no longer accessible.
+  static NodeMainInstance* Create(v8::Isolate* isolate,
+                                  uv_loop_t* event_loop,
+                                  MultiIsolatePlatform* platform,
+                                  const std::vector<std::string>& args,
+                                  const std::vector<std::string>& exec_args);
+  void Dispose();
 
-  NodeMainInstance(uv_loop_t* event_loop,
+  // Create a main instance that owns the isolate
+  NodeMainInstance(v8::Isolate::CreateParams* params,
+                   uv_loop_t* event_loop,
+                   MultiIsolatePlatform* platform,
                    const std::vector<std::string>& args,
                    const std::vector<std::string>& exec_args);
   ~NodeMainInstance();
@@ -27,16 +51,28 @@ class NodeMainInstance {
   // Start running the Node.js instances, return the exit code when finished.
   int Run();
 
- private:
   // TODO(joyeecheung): align this with the CreateEnvironment exposed in node.h
   // and the environment creation routine in workers somehow.
   std::unique_ptr<Environment> CreateMainEnvironment(int* exit_code);
 
+ private:
+  NodeMainInstance(const NodeMainInstance&) = delete;
+  NodeMainInstance& operator=(const NodeMainInstance&) = delete;
+  NodeMainInstance(NodeMainInstance&&) = delete;
+  NodeMainInstance& operator=(NodeMainInstance&&) = delete;
+
+  NodeMainInstance(v8::Isolate* isolate,
+                   uv_loop_t* event_loop,
+                   MultiIsolatePlatform* platform,
+                   const std::vector<std::string>& args,
+                   const std::vector<std::string>& exec_args);
   std::vector<std::string> args_;
   std::vector<std::string> exec_args_;
   std::unique_ptr<ArrayBufferAllocator> array_buffer_allocator_;
   v8::Isolate* isolate_;
+  MultiIsolatePlatform* platform_;
   std::unique_ptr<IsolateData> isolate_data_;
+  bool owns_isolate_ = false;
 };
 
 }  // namespace node