dgram: support dgram.send with multiple buffers

Added ability to dgram.send to send multiple buffers, _writev style.
The offset and length parameters in dgram.send are now optional.
Refactored the dgram benchmarks, and seperated them from net.
Added docs for the new signature.

Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>
Fixes: https://github.com/nodejs/node/issues/4302
PR-URL: https://github.com/nodejs/node/pull/4374

1 files changed, 45 insertions, 19 deletions

diff --git a/src/udp_wrap.cc b/src/udp_wrap.cc
index cb678f14fb..1faf45a95d 100644
--- a/src/udp_wrap.cc
+++ b/src/udp_wrap.cc
@@ -13,6 +13,7 @@
 
 namespace node {
 
+using v8::Array;
 using v8::Context;
 using v8::EscapableHandleScope;
 using v8::External;
@@ -35,6 +36,7 @@ class SendWrap : public ReqWrap<uv_udp_send_t> {
  public:
   SendWrap(Environment* env, Local<Object> req_wrap_obj, bool have_callback);
   inline bool have_callback() const;
+  size_t msg_size;
   size_t self_size() const override { return sizeof(*this); }
  private:
   const bool have_callback_;
@@ -243,29 +245,46 @@ void UDPWrap::DoSend(const FunctionCallbackInfo<Value>& args, int family) {
 
   UDPWrap* wrap = Unwrap<UDPWrap>(args.Holder());
 
-  // send(req, buffer, offset, length, port, address)
+  // send(req, buffer, port, address, hasCallback)
   CHECK(args[0]->IsObject());
-  CHECK(Buffer::HasInstance(args[1]));
+  CHECK(args[1]->IsArray());
   CHECK(args[2]->IsUint32());
   CHECK(args[3]->IsUint32());
-  CHECK(args[4]->IsUint32());
-  CHECK(args[5]->IsString());
-  CHECK(args[6]->IsBoolean());
+  CHECK(args[4]->IsString());
+  CHECK(args[5]->IsBoolean());
 
   Local<Object> req_wrap_obj = args[0].As<Object>();
-  Local<Object> buffer_obj = args[1].As<Object>();
-  size_t offset = args[2]->Uint32Value();
-  size_t length = args[3]->Uint32Value();
-  const unsigned short port = args[4]->Uint32Value();
-  node::Utf8Value address(env->isolate(), args[5]);
-  const bool have_callback = args[6]->IsTrue();
-
-  CHECK_LE(length, Buffer::Length(buffer_obj) - offset);
+  Local<Array> chunks = args[1].As<Array>();
+  // it is faster to fetch the length of the
+  // array in js-land
+  size_t count = args[2]->Uint32Value();
+  const unsigned short port = args[3]->Uint32Value();
+  node::Utf8Value address(env->isolate(), args[4]);
+  const bool have_callback = args[5]->IsTrue();
 
   SendWrap* req_wrap = new SendWrap(env, req_wrap_obj, have_callback);
+  size_t msg_size = 0;
+
+  // allocate uv_buf_t of the correct size
+  // if bigger than 16 elements
+  uv_buf_t bufs_[16];
+  uv_buf_t* bufs = bufs_;
+
+  if (ARRAY_SIZE(bufs_) < count)
+    bufs = new uv_buf_t[count];
+
+  // construct uv_buf_t array
+  for (size_t i = 0; i < count; i++) {
+    Local<Value> chunk = chunks->Get(i);
+
+    size_t length = Buffer::Length(chunk);
+
+    bufs[i] = uv_buf_init(Buffer::Data(chunk), length);
+    msg_size += length;
+  }
+
+  req_wrap->msg_size = msg_size;
 
-  uv_buf_t buf = uv_buf_init(Buffer::Data(buffer_obj) + offset,
-                             length);
   char addr[sizeof(sockaddr_in6)];
   int err;
 
@@ -284,12 +303,16 @@ void UDPWrap::DoSend(const FunctionCallbackInfo<Value>& args, int family) {
   if (err == 0) {
     err = uv_udp_send(&req_wrap->req_,
                       &wrap->handle_,
-                      &buf,
-                      1,
+                      bufs,
+                      count,
                       reinterpret_cast<const sockaddr*>(&addr),
                       OnSend);
   }
 
+  // Deallocate space
+  if (bufs != bufs_)
+    delete[] bufs;
+
   req_wrap->Dispatched();
   if (err)
     delete req_wrap;
@@ -332,8 +355,11 @@ void UDPWrap::OnSend(uv_udp_send_t* req, int status) {
     Environment* env = req_wrap->env();
     HandleScope handle_scope(env->isolate());
     Context::Scope context_scope(env->context());
-    Local<Value> arg = Integer::New(env->isolate(), status);
-    req_wrap->MakeCallback(env->oncomplete_string(), 1, &arg);
+    Local<Value> arg[] = {
+      Integer::New(env->isolate(), status),
+      Integer::New(env->isolate(), req_wrap->msg_size),
+    };
+    req_wrap->MakeCallback(env->oncomplete_string(), 2, arg);
   }
   delete req_wrap;
 }