From: Ben Darnell <ben@bendarnell.com>
Date: Mon, 17 Feb 2014 04:06:18 +0000 (-0500)
Subject: Add a fast path to stack_context when there are no active contexts.
X-Git-Tag: v4.0.0b1~121
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=47c7f63f2464125e3c4392f2c516d75ed7048cd5;p=thirdparty%2Ftornado.git

Add a fast path to stack_context when there are no active contexts.

This case is increasingly common now that coroutines are decoupled
from stack contexts.
---

diff --git a/tornado/stack_context.py b/tornado/stack_context.py
index b1e82b0e0..2e845ab27 100644
--- a/tornado/stack_context.py
+++ b/tornado/stack_context.py
@@ -266,6 +266,18 @@ def wrap(fn):
     # TODO: Any other better way to store contexts and update them in wrapped function?
     cap_contexts = [_state.contexts]
 
+    if not cap_contexts[0][0] and not cap_contexts[0][1]:
+        # Fast path when there are no active contexts.
+        def null_wrapper(*args, **kwargs):
+            try:
+                current_state = _state.contexts
+                _state.contexts = cap_contexts[0]
+                return fn(*args, **kwargs)
+            finally:
+                _state.contexts = current_state
+        null_wrapper._wrapped = True
+        return null_wrapper
+
     def wrapped(*args, **kwargs):
         ret = None
         try: