Ticket #12581: 12581.diff

django/db/__init__.py

@@ -2 +2 @@
 from django.core import signals
 from django.core.exceptions import ImproperlyConfigured
 from django.db.utils import ConnectionHandler, load_backend
+from django.utils.datastructures import RingBuffer
 from django.utils.functional import curry
 
 __all__ = ('backend', 'connection', 'connections', 'DatabaseError',
@@ -87 +88 @@
 # when a Django request is started.
 def reset_queries(**kwargs):
     for conn in connections.all():
-        conn.queries = []
+        conn.queries = RingBuffer(100)
 signals.request_started.connect(reset_queries)
 
 # Register an event that rolls back the connections

django/db/backends/__init__.py

@@ -4 +4 @@
 from django.db import DEFAULT_DB_ALIAS
 from django.db.backends import util
 from django.utils import datetime_safe
+from django.utils.datastructures import RingBuffer
 from django.utils.importlib import import_module
 
 class BaseDatabaseWrapper(local):
@@ -17 +18 @@
         # NAME, USER, etc. It's called `settings_dict` instead of `settings`
         # to disambiguate it from Django settings modules.
         self.connection = None
-        self.queries = []
+        self.queries = RingBuffer(100)
         self.settings_dict = settings_dict
         self.alias = alias
 

django/utils/datastructures.py

@@ +1 @@
+import collections
 from types import GeneratorType
 
 from django.utils.copycompat import deepcopy
@@ -447 +448 @@
             return self.func(value)
         return value
 
+class RingBuffer(collections.deque):
+    def __init__(self, size):
+        collections.deque.__init__(self)
+        self.size = size
+
+    def append(self, item):
+        collections.deque.append(self, item)
+        if len(self) > self.size:
+            self.popleft()
+
+    def get(self):
+        return list(self)
+

tests/regressiontests/datastructures/tests.py

@@ -159 +159 @@
 >>> "Normal: %(a)s. Modified: %(xx_a)s" % d
 'Normal: a. Modified: *a'
 
+### RingBuffer ##############################################################
+
+>>> r = RingBuffer(3)
+>>> r.append(1)
+>>> r.get()
+[1]
+>>> r.append(2)
+>>> r.append(3)
+>>> r.get()
+[1, 2, 3]
+>>> r.append(4)
+>>> r.get()
+[2, 3, 4]
+
 """