# HG changeset patch
# User Mads Kiilerich <madski@unity3d.com>
# Date 2015-12-25 11:37:49
# Node ID efce61aac33d492863e3c956328ed0e25be2527a
# Parent  2bf5e8731154a0bec3a0d6ad0ee0e84664daff37

db: handle race when multiple threads add the same cache invalidation entry simultaneously (Issue #177)

diff --git a/kallithea/model/db.py b/kallithea/model/db.py
--- a/kallithea/model/db.py
+++ b/kallithea/model/db.py
@@ -2142,7 +2142,13 @@ class CacheInvalidation(Base, BaseModel)
             return True
         inv_obj.cache_active = True
         Session().add(inv_obj)
-        Session().commit()
+        try:
+            Session().commit()
+        except exc.IntegrityError:
+            inv_obj = cls.query().filter(cls.cache_key == cache_key).scalar()
+            if not inv_obj:
+                raise
+            # TOCTOU - another thread added the key at the same time; no further action required
         return False
 
     @classmethod