worker: enable transferring WASM modules

Enable in-memory transfer of WASM modules without recompilation.

Previously, the serialization step worked, but deserialization failed
because we did not explicitly enable decoding inline WASM modules,
and so the message was not successfully received.

PR-URL: #25314
Reviewed-By: Gus Caplan <[email protected]>
Reviewed-By: Franziska Hinkelmann <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>

Author: addaleax

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 });
 }