http: misc optimizations and style fixes

PR-URL: nodejs#10558
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>

lib/_http_outgoing.js

@@ -136,36 +136,32 @@ OutgoingMessage.prototype._send = function _send(data, encoding, callback) {
 
 OutgoingMessage.prototype._writeRaw = _writeRaw;
 function _writeRaw(data, encoding, callback) {
+  const conn = this.connection;
+  if (conn && conn.destroyed) {
+    // The socket was destroyed. If we're still trying to write to it,
+    // then we haven't gotten the 'close' event yet.
+    return false;
+  }
+
   if (typeof encoding === 'function') {
     callback = encoding;
     encoding = null;
   }
 
-  var connection = this.connection;
-  if (connection &&
-      connection._httpMessage === this &&
-      connection.writable &&
-      !connection.destroyed) {
+  if (conn && conn._httpMessage === this && conn.writable && !conn.destroyed) {
     // There might be pending data in the this.output buffer.
-    var outputLength = this.output.length;
-    if (outputLength > 0) {
-      this._flushOutput(connection);
-    } else if (data.length === 0) {
+    if (this.output.length) {
+      this._flushOutput(conn);
+    } else if (!data.length) {
       if (typeof callback === 'function')
         process.nextTick(callback);
       return true;
     }
-
     // Directly write to socket.
-    return connection.write(data, encoding, callback);
-  } else if (connection && connection.destroyed) {
-    // The socket was destroyed.  If we're still trying to write to it,
-    // then we haven't gotten the 'close' event yet.
-    return false;
-  } else {
-    // buffer, as long as we're not destroyed.
-    return this._buffer(data, encoding, callback);
+    return conn.write(data, encoding, callback);
   }
+  // Buffer, as long as we're not destroyed.
+  return this._buffer(data, encoding, callback);
 }
 
 
@@ -477,6 +473,7 @@ Object.defineProperty(OutgoingMessage.prototype, 'headersSent', {
 });
 
 
+const crlf_buf = Buffer.from('\r\n');
 OutgoingMessage.prototype.write = function write(chunk, encoding, callback) {
   if (this.finished) {
     var err = new Error('write after end');
@@ -583,9 +580,6 @@ OutgoingMessage.prototype.addTrailers = function addTrailers(headers) {
   }
 };
 
-
-const crlf_buf = Buffer.from('\r\n');
-
 function onFinish(outmsg) {
   outmsg.emit('finish');
 }

lib/_http_server.js

@@ -170,8 +170,8 @@ function writeHead(statusCode, reason, obj) {
     this.statusMessage = reason;
   } else {
     // writeHead(statusCode[, headers])
-    this.statusMessage =
-        this.statusMessage || STATUS_CODES[statusCode] || 'unknown';
+    if (!this.statusMessage)
+      this.statusMessage = STATUS_CODES[statusCode] || 'unknown';
     obj = reason;
   }
   this.statusCode = statusCode;
@@ -514,9 +514,8 @@ function parserOnIncoming(server, socket, state, req, keepAlive) {
   // so that we don't become overwhelmed by a flood of
   // pipelined requests that may never be resolved.
   if (!socket._paused) {
-    var needPause = socket._writableState.needDrain ||
-        state.outgoingData >= socket._writableState.highWaterMark;
-    if (needPause) {
+    var ws = socket._writableState;
+    if (ws.needDrain || state.outgoingData >= ws.highWaterMark) {
       socket._paused = true;
       // We also need to pause the parser, but don't do that until after
       // the call to execute, because we may still be processing the last
@@ -542,9 +541,7 @@ function parserOnIncoming(server, socket, state, req, keepAlive) {
 
   // When we're finished writing the response, check if this is the last
   // response, if so destroy the socket.
-  var finish =
-    resOnFinish.bind(undefined, req, res, socket, state);
-  res.on('finish', finish);
+  res.on('finish', resOnFinish.bind(undefined, req, res, socket, state));
 
   if (req.headers.expect !== undefined &&
       (req.httpVersionMajor === 1 && req.httpVersionMinor === 1)) {