dgram: refactor SO_RCVBUF and SO_SNDBUF methods

This commit refactors the get/set send/receive buffer size
methods in the following ways:

- Use booleans instead of strings and numbers to differentiate
between the send and receive buffers.
- Reduce the amount of branching and complexity in the C++ code.

Refs: https://github.com/nodejs/node/pull/13623
PR-URL: https://github.com/nodejs/node/pull/15483
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/dgram.js

@@ -40,6 +40,9 @@ const BIND_STATE_UNBOUND = 0;
 const BIND_STATE_BINDING = 1;
 const BIND_STATE_BOUND = 2;
 
+const RECV_BUFFER = true;
+const SEND_BUFFER = false;
+
 // Lazily loaded
 var cluster = null;
 
@@ -146,10 +149,10 @@ function startListening(socket) {
   socket.fd = -42; // compatibility hack
 
   if (socket[kOptionSymbol].recvBufferSize)
-    bufferSize(socket, socket[kOptionSymbol].recvBufferSize, 'recv');
+    bufferSize(socket, socket[kOptionSymbol].recvBufferSize, RECV_BUFFER);
 
   if (socket[kOptionSymbol].sendBufferSize)
-    bufferSize(socket, socket[kOptionSymbol].sendBufferSize, 'send');
+    bufferSize(socket, socket[kOptionSymbol].sendBufferSize, SEND_BUFFER);
 
   socket.emit('listening');
 }
@@ -172,10 +175,7 @@ function bufferSize(self, size, buffer) {
     throw new errors.TypeError('ERR_SOCKET_BAD_BUFFER_SIZE');
 
   try {
-    if (buffer === 'recv')
-      return self._handle.bufferSize(size, 0);
-    else
-      return self._handle.bufferSize(size, 1);
+    return self._handle.bufferSize(size, buffer);
   } catch (e) {
     throw new errors.Error('ERR_SOCKET_BUFFER_SIZE', e);
   }
@@ -677,22 +677,22 @@ Socket.prototype.unref = function() {
 
 
 Socket.prototype.setRecvBufferSize = function(size) {
-  bufferSize(this, size, 'recv');
+  bufferSize(this, size, RECV_BUFFER);
 };
 
 
 Socket.prototype.setSendBufferSize = function(size) {
-  bufferSize(this, size, 'send');
+  bufferSize(this, size, SEND_BUFFER);
 };
 
 
 Socket.prototype.getRecvBufferSize = function() {
-  return bufferSize(this, 0, 'recv');
+  return bufferSize(this, 0, RECV_BUFFER);
 };
 
 
 Socket.prototype.getSendBufferSize = function() {
-  return bufferSize(this, 0, 'send');
+  return bufferSize(this, 0, SEND_BUFFER);
 };
 
 

src/udp_wrap.cc

@@ -233,31 +233,26 @@ void UDPWrap::BufferSize(const FunctionCallbackInfo<Value>& args) {
                           args.GetReturnValue().Set(UV_EBADF));
 
   CHECK(args[0]->IsUint32());
-  CHECK(args[1]->IsUint32());
+  CHECK(args[1]->IsBoolean());
+  bool is_recv = args[1].As<v8::Boolean>()->Value();
+  const char* uv_func_name = is_recv ? "uv_recv_buffer_size" :
+                                       "uv_send_buffer_size";
 
-  if (!args[0]->IsInt32()) {
-    if (args[1].As<Uint32>()->Value() == 0)
-      return env->ThrowUVException(UV_EINVAL, "uv_recv_buffer_size");
-    else
-      return env->ThrowUVException(UV_EINVAL, "uv_send_buffer_size");
-  }
+  if (!args[0]->IsInt32())
+    return env->ThrowUVException(UV_EINVAL, uv_func_name);
 
-  int err;
+  uv_handle_t* handle = reinterpret_cast<uv_handle_t*>(&wrap->handle_);
   int size = static_cast<int>(args[0].As<Uint32>()->Value());
-  if (args[1].As<Uint32>()->Value() == 0) {
-    err = uv_recv_buffer_size(reinterpret_cast<uv_handle_t*>(&wrap->handle_),
-                              &size);
-  } else {
-    err = uv_send_buffer_size(reinterpret_cast<uv_handle_t*>(&wrap->handle_),
-                              &size);
-  }
+  int err;
+
+  if (is_recv)
+    err = uv_recv_buffer_size(handle, &size);
+  else
+    err = uv_send_buffer_size(handle, &size);
+
+  if (err != 0)
+    return env->ThrowUVException(err, uv_func_name);
 
-  if (err != 0) {
-    if (args[1].As<Uint32>()->Value() == 0)
-      return env->ThrowUVException(err, "uv_recv_buffer_size");
-    else
-      return env->ThrowUVException(err, "uv_send_buffer_size");
-  }
   args.GetReturnValue().Set(size);
 }