worker: improve MessagePort performance

Use a JS function as the single entry point for emitting `.onmessage()`
calls, avoiding the overhead of manually constructing each message
event object in C++.

                                                                             confidence improvement accuracy (*)   (**)  (***)
    worker/echo.js n=100000 sendsPerBroadcast=1 payload='object' workers=1         ***     16.34 %       ±1.16% ±1.54% ±1.99%
    worker/echo.js n=100000 sendsPerBroadcast=1 payload='string' workers=1         ***     24.41 %       ±1.50% ±1.99% ±2.58%
    worker/echo.js n=100000 sendsPerBroadcast=10 payload='object' workers=1        ***     26.66 %       ±1.54% ±2.05% ±2.65%
    worker/echo.js n=100000 sendsPerBroadcast=10 payload='string' workers=1        ***     32.72 %       ±1.60% ±2.11% ±2.73%
    worker/messageport.js n=1000000 payload='object'                               ***     40.28 %       ±1.48% ±1.95% ±2.52%
    worker/messageport.js n=1000000 payload='string'                               ***     76.95 %       ±2.19% ±2.90% ±3.75%

Also fix handling exceptions returned from `MessagePort::New`.

PR-URL: https://github.com/nodejs/node/pull/31605
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/node_messaging.h b/src/node_messaging.h
index 6d2410a7248..d687e7549d5 100644
--- a/src/node_messaging.h
+++ b/src/node_messaging.h
@@ -131,12 +131,16 @@ class MessagePortData : public MemoryRetainer {
 // the uv_async_t handle that is used to notify the current event loop of
 // new incoming messages.
 class MessagePort : public HandleWrap {
- public:
+ private:
   // Create a new MessagePort. The `context` argument specifies the Context
   // instance that is used for creating the values emitted from this port.
+  // This is called by MessagePort::New(), which is the public API used for
+  // creating MessagePort instances.
   MessagePort(Environment* env,
               v8::Local<v8::Context> context,
               v8::Local<v8::Object> wrap);
+
+ public:
   ~MessagePort() override;
 
   // Create a new message port instance, optionally over an existing
@@ -205,6 +209,7 @@ class MessagePort : public HandleWrap {
   std::unique_ptr<MessagePortData> data_ = nullptr;
   bool receiving_messages_ = false;
   uv_async_t async_;
+  v8::Global<v8::Function> emit_message_fn_;
 
   friend class MessagePortData;
 };