src: don't call v8::Object::SetHiddenValue()

Don't use v8::Object::SetHiddenValue() to keep a reference alive to the
buffer, we can just as easily do that from JS land and it's a lot faster
to boot.

Because the buffer is now a visible property of the write request
object, it's essential that we do *not* log it - we'd be effectively
serializing the whole buffer to a pretty-printed string.

lib/dgram.js

@@ -301,7 +301,7 @@ Socket.prototype.send = function(buffer,
       self.emit('error', ex);
     }
     else if (self._handle) {
-      var req = {};
+      var req = { buffer: buffer };  // Keep reference alive.
       if (callback) {
         req.callback = callback;
         req.oncomplete = afterSend;

lib/net.js

@@ -640,7 +640,13 @@ Socket.prototype._writeGeneric = function(writev, data, encoding, cb) {
     // Retain chunks
     if (err === 0) req._chunks = chunks;
   } else {
-    var enc = util.isBuffer(data) ? 'buffer' : encoding;
+    var enc;
+    if (util.isBuffer(data)) {
+      req.buffer = data;  // Keep reference alive.
+      enc = 'buffer';
+    } else {
+      enc = encoding;
+    }
     err = createWriteReq(req, this._handle, data, enc);
   }
 
@@ -743,7 +749,7 @@ function afterWrite(status, handle, req) {
   var self = handle.owner;
   var state = self._writableState;
   if (self !== process.stderr && self !== process.stdout)
-    debug('afterWrite', status, req);
+    debug('afterWrite', status);
 
   // callback may come after call to destroy.
   if (self.destroyed) {

src/stream_wrap.cc

@@ -49,7 +49,6 @@ using v8::Undefined;
 using v8::Value;
 
 
-static Cached<String> buffer_sym;
 static Cached<String> bytes_sym;
 static Cached<String> write_queue_size_sym;
 static Cached<String> onread_sym;
@@ -63,7 +62,6 @@ void StreamWrap::Initialize(Handle<Object> target) {
   initialized = true;
 
   HandleScope scope(node_isolate);
-  buffer_sym = FIXED_ONE_BYTE_STRING(node_isolate, "buffer");
   bytes_sym = FIXED_ONE_BYTE_STRING(node_isolate, "bytes");
   write_queue_size_sym = FIXED_ONE_BYTE_STRING(node_isolate, "writeQueueSize");
   onread_sym = FIXED_ONE_BYTE_STRING(node_isolate, "onread");
@@ -215,8 +213,6 @@ void StreamWrap::WriteBuffer(const FunctionCallbackInfo<Value>& args) {
   char* storage = new char[sizeof(WriteWrap)];
   WriteWrap* req_wrap = new(storage) WriteWrap(req_wrap_obj, wrap);
 
-  req_wrap_obj->SetHiddenValue(buffer_sym, buf_obj);
-
   uv_buf_t buf;
   WriteBuffer(buf_obj, &buf);
 

src/udp_wrap.cc

@@ -57,7 +57,6 @@ class SendWrap : public ReqWrap<uv_udp_send_t> {
 
 
 static Persistent<Function> constructor;
-static Cached<String> buffer_sym;
 static Cached<String> oncomplete_sym;
 static Cached<String> onmessage_sym;
 
@@ -87,7 +86,6 @@ UDPWrap::~UDPWrap() {
 void UDPWrap::Initialize(Handle<Object> target) {
   HandleScope scope(node_isolate);
 
-  buffer_sym = FIXED_ONE_BYTE_STRING(node_isolate, "buffer");
   oncomplete_sym = FIXED_ONE_BYTE_STRING(node_isolate, "oncomplete");
   onmessage_sym = FIXED_ONE_BYTE_STRING(node_isolate, "onmessage");
 
@@ -261,7 +259,6 @@ void UDPWrap::DoSend(const FunctionCallbackInfo<Value>& args, int family) {
   assert(length <= Buffer::Length(buffer_obj) - offset);
 
   SendWrap* req_wrap = new SendWrap(req_wrap_obj, have_callback);
-  req_wrap->object()->SetHiddenValue(buffer_sym, buffer_obj);
 
   uv_buf_t buf = uv_buf_init(Buffer::Data(buffer_obj) + offset,
                              length);