src: remove HasWriteQueue()

Tests are passing without it, and this otherwise makes the
code harder to reason about because the `async` flag on the
write request object would not be set even though the callback
would still be pending.

PR-URL: nodejs#18019
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/stream_base.cc

@@ -195,8 +195,7 @@ int StreamBase::Writev(const FunctionCallbackInfo<Value>& args) {
   }
 
   err = DoWrite(req_wrap, buf_list, count, nullptr);
-  if (HasWriteQueue())
-    req_wrap_obj->Set(env->async(), True(env->isolate()));
+  req_wrap_obj->Set(env->async(), True(env->isolate()));
 
   if (err)
     req_wrap->Dispose();
@@ -254,8 +253,7 @@ int StreamBase::WriteBuffer(const FunctionCallbackInfo<Value>& args) {
   }
 
   err = DoWrite(req_wrap, bufs, count, nullptr);
-  if (HasWriteQueue())
-    req_wrap_obj->Set(env->async(), True(env->isolate()));
+  req_wrap_obj->Set(env->async(), True(env->isolate()));
   req_wrap_obj->Set(env->buffer_string(), args[1]);
 
   if (err)
@@ -381,8 +379,7 @@ int StreamBase::WriteString(const FunctionCallbackInfo<Value>& args) {
         reinterpret_cast<uv_stream_t*>(send_handle));
   }
 
-  if (HasWriteQueue())
-    req_wrap_obj->Set(env->async(), True(env->isolate()));
+  req_wrap_obj->Set(env->async(), True(env->isolate()));
 
   if (err)
     req_wrap->Dispose();
@@ -476,10 +473,6 @@ int StreamResource::DoTryWrite(uv_buf_t** bufs, size_t* count) {
   return 0;
 }
 
-bool StreamResource::HasWriteQueue() {
-  return true;
-}
-
 
 const char* StreamResource::Error() const {
   return nullptr;

src/stream_base.h

@@ -162,7 +162,6 @@ class StreamResource {
                       uv_buf_t* bufs,
                       size_t count,
                       uv_stream_t* send_handle) = 0;
-  virtual bool HasWriteQueue();
   virtual const char* Error() const;
   virtual void ClearError();
 

src/stream_wrap.cc

@@ -380,10 +380,6 @@ int LibuvStreamWrap::DoWrite(WriteWrap* w,
 }
 
 
-bool LibuvStreamWrap::HasWriteQueue() {
-  return stream()->write_queue_size > 0;
-}
-
 
 void LibuvStreamWrap::AfterUvWrite(uv_write_t* req, int status) {
   WriteWrap* req_wrap = WriteWrap::from_req(req);

src/stream_wrap.h

@@ -55,7 +55,6 @@ class LibuvStreamWrap : public HandleWrap, public StreamBase {
               uv_buf_t* bufs,
               size_t count,
               uv_stream_t* send_handle) override;
-  bool HasWriteQueue() override;
 
   inline uv_stream_t* stream() const {
     return stream_;