http: destroy clean incoming messages in one tick

When an incoming message is destroyed after being fully received with
no error, complete the destroy synchronously instead of deferring the
callback with process.nextTick(). The deferral only exists so that
'error' listeners attached right after destroy(err) still receive the
error, which cannot matter when there is no error. 'close' is still
emitted asynchronously by the stream machinery.

Reduces the per-request nextTick count of a hello-world HTTP server
from 6 to 5.

Signed-off-by: Matteo Collina <hello@matteocollina.com>

Author: mcollina

lib/_http_incoming.js

@@ -299,6 +299,13 @@ IncomingMessage.prototype._destroy = function _destroy(err, cb) {
       cleanup();
       process.nextTick(onError, this, e || err, cb);
     });
+  } else if (err == null && !this.aborted) {
+    // The message was received completely and is being destroyed cleanly:
+    // complete the destroy synchronously. 'close' is still emitted on a
+    // later tick by the stream machinery. The deferral below only exists
+    // so that 'error' listeners attached right after destroy(err) still
+    // receive the error, which cannot matter when there is no error.
+    cb();
   } else {
     process.nextTick(onError, this, err, cb);
   }