src,stream: change return type to Maybe

This changes the return types of some functions to indicate that
the functions may have a pending exception, and removes some of
todos related.

Signed-off-by: Daeyeon Jeong daeyeon.dev@gmail.com

PR-URL: nodejs/node#43575
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

src/stream_wrap.cc

@@ -25,6 +25,7 @@
 #include "env-inl.h"
 #include "handle_wrap.h"
 #include "node_buffer.h"
+#include "node_errors.h"
 #include "node_external_reference.h"
 #include "pipe_wrap.h"
 #include "req_wrap-inl.h"
@@ -38,14 +39,18 @@
 
 namespace node {
 
+using errors::TryCatchScope;
 using v8::Context;
 using v8::DontDelete;
 using v8::EscapableHandleScope;
 using v8::FunctionCallbackInfo;
 using v8::FunctionTemplate;
 using v8::HandleScope;
+using v8::JustVoid;
 using v8::Local;
+using v8::Maybe;
 using v8::MaybeLocal;
+using v8::Nothing;
 using v8::Object;
 using v8::PropertyAttribute;
 using v8::ReadOnly;
@@ -191,15 +196,19 @@ bool LibuvStreamWrap::IsIPCPipe() {
   return is_named_pipe_ipc();
 }
 
-
 int LibuvStreamWrap::ReadStart() {
-  return uv_read_start(stream(), [](uv_handle_t* handle,
-                                    size_t suggested_size,
-                                    uv_buf_t* buf) {
-    static_cast<LibuvStreamWrap*>(handle->data)->OnUvAlloc(suggested_size, buf);
-  }, [](uv_stream_t* stream, ssize_t nread, const uv_buf_t* buf) {
-    static_cast<LibuvStreamWrap*>(stream->data)->OnUvRead(nread, buf);
-  });
+  return uv_read_start(
+      stream(),
+      [](uv_handle_t* handle, size_t suggested_size, uv_buf_t* buf) {
+        static_cast<LibuvStreamWrap*>(handle->data)
+            ->OnUvAlloc(suggested_size, buf);
+      },
+      [](uv_stream_t* stream, ssize_t nread, const uv_buf_t* buf) {
+        LibuvStreamWrap* wrap = static_cast<LibuvStreamWrap*>(stream->data);
+        TryCatchScope try_catch(wrap->env());
+        try_catch.SetVerbose(true);
+        wrap->OnUvRead(nread, buf);
+      });
 }
 
 
@@ -239,8 +248,7 @@ static MaybeLocal<Object> AcceptHandle(Environment* env,
   return scope.Escape(wrap_obj);
 }
 
-
-void LibuvStreamWrap::OnUvRead(ssize_t nread, const uv_buf_t* buf) {
+Maybe<void> LibuvStreamWrap::OnUvRead(ssize_t nread, const uv_buf_t* buf) {
   HandleScope scope(env()->isolate());
   Context::Scope context_scope(env()->context());
   uv_handle_type type = UV_UNKNOWN_HANDLE;
@@ -268,18 +276,21 @@ void LibuvStreamWrap::OnUvRead(ssize_t nread, const uv_buf_t* buf) {
     }
 
     Local<Object> local_pending_obj;
-    if (pending_obj.ToLocal(&local_pending_obj) &&
-          object()->Set(env()->context(),
-                        env()->pending_handle_string(),
-                        local_pending_obj).IsNothing()) {
-      return;
+    if (type != UV_UNKNOWN_HANDLE &&
+        (!pending_obj.ToLocal(&local_pending_obj) ||
+         object()
+             ->Set(env()->context(),
+                   env()->pending_handle_string(),
+                   local_pending_obj)
+             .IsNothing())) {
+      return Nothing<void>();
     }
   }
 
   EmitRead(nread, *buf);
+  return JustVoid();
 }
 
-
 void LibuvStreamWrap::GetWriteQueueSize(
     const FunctionCallbackInfo<Value>& info) {
   LibuvStreamWrap* wrap;

src/stream_wrap.h

@@ -105,9 +105,7 @@ class LibuvStreamWrap : public HandleWrap, public StreamBase {
 
   // Callbacks for libuv
   void OnUvAlloc(size_t suggested_size, uv_buf_t* buf);
-  // TODO(RaisinTen): Update the return type to a Maybe, so that we can indicate
-  // if there is a pending exception/termination.
-  void OnUvRead(ssize_t nread, const uv_buf_t* buf);
+  v8::Maybe<void> OnUvRead(ssize_t nread, const uv_buf_t* buf);
 
   static void AfterUvWrite(uv_write_t* req, int status);
   static void AfterUvShutdown(uv_shutdown_t* req, int status);