From 818b4bf8b354d43360e3fd9d0b10440636a25212 Mon Sep 17 00:00:00 2001
From: Val Neekman <val@neekware.com>
Date: Thu, 27 Feb 2014 12:27:54 -0800
Subject: [PATCH] handle negative time value and prevent a divide by zero

---
 rest_framework/throttling.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/rest_framework/throttling.py b/rest_framework/throttling.py
index a946d837f..efa9fb949 100644
--- a/rest_framework/throttling.py
+++ b/rest_framework/throttling.py
@@ -136,6 +136,8 @@ class SimpleRateThrottle(BaseThrottle):
             remaining_duration = self.duration
 
         available_requests = self.num_requests - len(self.history) + 1
+        if available_requests <= 0:
+            return None
 
         return remaining_duration / float(available_requests)