src: support V8 experimental shared values in messaging

PR-URL: https://github.com/nodejs/node/pull/47706
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

src/node_messaging.cc

@@ -31,6 +31,7 @@ using v8::MaybeLocal;
 using v8::Nothing;
 using v8::Object;
 using v8::SharedArrayBuffer;
+using v8::SharedValueConveyor;
 using v8::String;
 using v8::Symbol;
 using v8::Value;
@@ -92,10 +93,12 @@ class DeserializerDelegate : public ValueDeserializer::Delegate {
       Environment* env,
       const std::vector<BaseObjectPtr<BaseObject>>& host_objects,
       const std::vector<Local<SharedArrayBuffer>>& shared_array_buffers,
-      const std::vector<CompiledWasmModule>& wasm_modules)
+      const std::vector<CompiledWasmModule>& wasm_modules,
+      const std::optional<SharedValueConveyor>& shared_value_conveyor)
       : host_objects_(host_objects),
         shared_array_buffers_(shared_array_buffers),
-        wasm_modules_(wasm_modules) {}
+        wasm_modules_(wasm_modules),
+        shared_value_conveyor_(shared_value_conveyor) {}
 
   MaybeLocal<Object> ReadHostObject(Isolate* isolate) override {
     // Identifying the index in the message's BaseObject array is sufficient.
@@ -128,12 +131,18 @@ class DeserializerDelegate : public ValueDeserializer::Delegate {
         isolate, wasm_modules_[transfer_id]);
   }
 
+  const SharedValueConveyor* GetSharedValueConveyor(Isolate* isolate) override {
+    CHECK(shared_value_conveyor_.has_value());
+    return &shared_value_conveyor_.value();
+  }
+
   ValueDeserializer* deserializer = nullptr;
 
  private:
   const std::vector<BaseObjectPtr<BaseObject>>& host_objects_;
   const std::vector<Local<SharedArrayBuffer>>& shared_array_buffers_;
   const std::vector<CompiledWasmModule>& wasm_modules_;
+  const std::optional<SharedValueConveyor>& shared_value_conveyor_;
 };
 
 }  // anonymous namespace
@@ -198,8 +207,12 @@ MaybeLocal<Value> Message::Deserialize(Environment* env,
     shared_array_buffers.push_back(sab);
   }
 
-  DeserializerDelegate delegate(
-      this, env, host_objects, shared_array_buffers, wasm_modules_);
+  DeserializerDelegate delegate(this,
+                                env,
+                                host_objects,
+                                shared_array_buffers,
+                                wasm_modules_,
+                                shared_value_conveyor_);
   ValueDeserializer deserializer(
       env->isolate(),
       reinterpret_cast<const uint8_t*>(main_message_buf_.data),
@@ -243,6 +256,10 @@ uint32_t Message::AddWASMModule(CompiledWasmModule&& mod) {
   return wasm_modules_.size() - 1;
 }
 
+void Message::AdoptSharedValueConveyor(SharedValueConveyor&& conveyor) {
+  shared_value_conveyor_.emplace(std::move(conveyor));
+}
+
 namespace {
 
 MaybeLocal<Function> GetEmitMessageFunction(Local<Context> context) {
@@ -347,6 +364,12 @@ class SerializerDelegate : public ValueSerializer::Delegate {
     return Just(msg_->AddWASMModule(module->GetCompiledModule()));
   }
 
+  bool AdoptSharedValueConveyor(Isolate* isolate,
+                                SharedValueConveyor&& conveyor) override {
+    msg_->AdoptSharedValueConveyor(std::move(conveyor));
+    return true;
+  }
+
   Maybe<bool> Finish(Local<Context> context) {
     for (uint32_t i = 0; i < host_objects_.size(); i++) {
       BaseObjectPtr<BaseObject> host_object = std::move(host_objects_[i]);

src/node_messaging.h

@@ -88,6 +88,9 @@ class Message : public MemoryRetainer {
   // Internal method of Message that is called when a new WebAssembly.Module
   // object is encountered in the incoming value's structure.
   uint32_t AddWASMModule(v8::CompiledWasmModule&& mod);
+  // Internal method of Message that is called when a shared value is
+  // encountered for the first time in the incoming value's structure.
+  void AdoptSharedValueConveyor(v8::SharedValueConveyor&& conveyor);
 
   // The host objects that will be transferred, as recorded by Serialize()
   // (e.g. MessagePorts).
@@ -114,6 +117,7 @@ class Message : public MemoryRetainer {
   std::vector<std::shared_ptr<v8::BackingStore>> shared_array_buffers_;
   std::vector<std::unique_ptr<TransferData>> transferables_;
   std::vector<v8::CompiledWasmModule> wasm_modules_;
+  std::optional<v8::SharedValueConveyor> shared_value_conveyor_;
 
   friend class MessagePort;
 };

test/parallel/test-experimental-shared-value-conveyor.js

@@ -0,0 +1,25 @@
+'use strict';
+
+// Flags: --harmony-struct
+
+const common = require('../common');
+const assert = require('assert');
+const { Worker, parentPort } = require('worker_threads');
+
+// Do not use isMainThread so that this test itself can be run inside a Worker.
+if (!process.env.HAS_STARTED_WORKER) {
+  process.env.HAS_STARTED_WORKER = 1;
+  const m = new globalThis.SharedArray(16);
+
+  const worker = new Worker(__filename);
+  worker.once('message', common.mustCall((message) => {
+    assert.strictEqual(message, m);
+  }));
+
+  worker.postMessage(m);
+} else {
+  parentPort.once('message', common.mustCall((message) => {
+    // Simple echo.
+    parentPort.postMessage(message);
+  }));
+}