worker: enable transferring WASM modules

src/node_messaging.cc

@@ -30,6 +30,7 @@ using v8::String;
 using v8::Value;
 using v8::ValueDeserializer;
 using v8::ValueSerializer;
+using v8::WasmCompiledModule;
 
 namespace node {
 namespace worker {
@@ -43,13 +44,15 @@ namespace {
 // `MessagePort`s and `SharedArrayBuffer`s, and make new JS objects out of them.
 class DeserializerDelegate : public ValueDeserializer::Delegate {
  public:
-  DeserializerDelegate(Message* m,
-                       Environment* env,
-                       const std::vector<MessagePort*>& message_ports,
-                       const std::vector<Local<SharedArrayBuffer>>&
-                           shared_array_buffers)
-    : message_ports_(message_ports),
-      shared_array_buffers_(shared_array_buffers) {}
+  DeserializerDelegate(
+      Message* m,
+      Environment* env,
+      const std::vector<MessagePort*>& message_ports,
+      const std::vector<Local<SharedArrayBuffer>>& shared_array_buffers,
+      const std::vector<WasmCompiledModule::TransferrableModule>& wasm_modules)
+      : message_ports_(message_ports),
+        shared_array_buffers_(shared_array_buffers),
+        wasm_modules_(wasm_modules) {}
 
   MaybeLocal<Object> ReadHostObject(Isolate* isolate) override {
     // Currently, only MessagePort hosts objects are supported, so identifying
@@ -67,11 +70,19 @@ class DeserializerDelegate : public ValueDeserializer::Delegate {
     return shared_array_buffers_[clone_id];
   }
 
+  MaybeLocal<WasmCompiledModule> GetWasmModuleFromId(
+      Isolate* isolate, uint32_t transfer_id) override {
+    CHECK_LE(transfer_id, wasm_modules_.size());
+    return WasmCompiledModule::FromTransferrableModule(
+        isolate, wasm_modules_[transfer_id]);
+  }
+
   ValueDeserializer* deserializer = nullptr;
 
  private:
   const std::vector<MessagePort*>& message_ports_;
   const std::vector<Local<SharedArrayBuffer>>& shared_array_buffers_;
+  const std::vector<WasmCompiledModule::TransferrableModule>& wasm_modules_;
 };
 
 }  // anonymous namespace
@@ -109,7 +120,8 @@ MaybeLocal<Value> Message::Deserialize(Environment* env,
   }
   shared_array_buffers_.clear();
 
-  DeserializerDelegate delegate(this, env, ports, shared_array_buffers);
+  DeserializerDelegate delegate(
+      this, env, ports, shared_array_buffers, wasm_modules_);
   ValueDeserializer deserializer(
       env->isolate(),
       reinterpret_cast<const uint8_t*>(main_message_buf_.data),
@@ -143,6 +155,11 @@ void Message::AddMessagePort(std::unique_ptr<MessagePortData>&& data) {
   message_ports_.emplace_back(std::move(data));
 }
 
+uint32_t Message::AddWASMModule(WasmCompiledModule::TransferrableModule&& mod) {
+  wasm_modules_.emplace_back(std::move(mod));
+  return wasm_modules_.size() - 1;
+}
+
 namespace {
 
 void ThrowDataCloneException(Environment* env, Local<String> message) {
@@ -202,6 +219,11 @@ class SerializerDelegate : public ValueSerializer::Delegate {
     return Just(i);
   }
 
+  Maybe<uint32_t> GetWasmModuleTransferId(
+      Isolate* isolate, Local<WasmCompiledModule> module) override {
+    return Just(msg_->AddWASMModule(module->GetTransferrableModule()));
+  }
+
   void Finish() {
     // Only close the MessagePort handles and actually transfer them
     // once we know that serialization succeeded.

src/node_messaging.h

@@ -47,6 +47,9 @@ class Message : public MemoryRetainer {
   // Internal method of Message that is called once serialization finishes
   // and that transfers ownership of `data` to this message.
   void AddMessagePort(std::unique_ptr<MessagePortData>&& data);
+  // 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::WasmCompiledModule::TransferrableModule&& mod);
 
   // The MessagePorts that will be transferred, as recorded by Serialize().
   // Used for warning user about posting the target MessagePort to itself,
@@ -65,6 +68,7 @@ class Message : public MemoryRetainer {
   std::vector<MallocedBuffer<char>> array_buffer_contents_;
   std::vector<SharedArrayBufferMetadataReference> shared_array_buffers_;
   std::vector<std::unique_ptr<MessagePortData>> message_ports_;
+  std::vector<v8::WasmCompiledModule::TransferrableModule> wasm_modules_;
 
   friend class MessagePort;
 };

test/parallel/test-worker-message-port-wasm-module.js

@@ -0,0 +1,19 @@
+// Flags: --experimental-worker
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const fixtures = require('../common/fixtures');
+
+const { Worker } = require('worker_threads');
+const wasmModule = new WebAssembly.Module(fixtures.readSync('test.wasm'));
+
+const worker = new Worker(`
+const { parentPort } = require('worker_threads');
+parentPort.once('message', ({ wasmModule }) => {
+  const instance = new WebAssembly.Instance(wasmModule);
+  parentPort.postMessage(instance.exports.addTwo(10, 20));
+});
+`, { eval: true });
+
+worker.once('message', common.mustCall((num) => assert.strictEqual(num, 30)));
+worker.postMessage({ wasmModule });

test/parallel/test-worker-message-port-wasm-threads.js

@@ -32,15 +32,23 @@ assert(buffer instanceof SharedArrayBuffer);
   // stopped when we exit.
   const worker = new Worker(`
   const { parentPort } = require('worker_threads');
+
+  // Compile the same WASM module from its source bytes.
   const wasmSource = new Uint8Array([${wasmSource.join(',')}]);
   const wasmModule = new WebAssembly.Module(wasmSource);
   const instance = new WebAssembly.Instance(wasmModule);
   parentPort.postMessage(instance.exports.memory);
+
+  // Do the same thing, except we receive the WASM module via transfer.
+  parentPort.once('message', ({ wasmModule }) => {
+    const instance = new WebAssembly.Instance(wasmModule);
+    parentPort.postMessage(instance.exports.memory);
+  });
   `, { eval: true });
-  worker.once('message', common.mustCall(({ buffer }) => {
+  worker.on('message', common.mustCall(({ buffer }) => {
     assert(buffer instanceof SharedArrayBuffer);
     worker.buf = buffer; // Basically just keep the reference to buffer alive.
-  }));
+  }, 2));
   worker.once('exit', common.mustCall());
   worker.postMessage({ wasmModule });
 }