apps/debug_toolbar/panels/cache.py

   1 from debug_toolbar.panels import DebugPanel
   2 try: from cStringIO import StringIO
   3 except ImportError: import StringIO
   4 from django.core import cache
   5 from django.core.cache.backends.base import BaseCache
   6 import time
   7 import inspect
   8 import os.path
   9 from django.template.loader import render_to_string
  10
  11 class CacheStatTracker(BaseCache):
  12     """A small class used to track cache calls."""
  13     def __init__(self, cache):
  14         self.cache = cache
  15         self.reset()
  16
  17     def reset(self):
  18         self.calls = []
  19         self.hits = 0
  20         self.misses = 0
  21         self.sets = 0
  22         self.gets = 0
  23         self.get_many = 0
  24         self.deletes = 0
  25         self.total_time = 0
  26
  27     def _get_func_info(self):
  28         stack = inspect.stack()[2]
  29         return (os.path.basename(stack[1]), stack[2], stack[3], stack[4])
  30
  31     def get(self, key, default=None):
  32         t = time.time()
  33         value = self.cache.get(key, default)
  34         this_time = time.time()-t
  35         self.total_time += this_time*1000
  36         if value is None:
  37             self.misses += 1
  38         else:
  39             self.hits += 1
  40         self.gets += 1
  41         self.calls.append((this_time, 'get', (key,), self._get_func_info()))
  42         return value
  43
  44     def set(self, key, value, timeout=None):
  45         t = time.time()
  46         self.cache.set(key, value, timeout)
  47         this_time = time.time()-t
  48         self.total_time += this_time*1000
  49         self.sets += 1
  50         self.calls.append((this_time, 'set', (key, value, timeout), self._get_func_info()))
  51
  52     def delete(self, key):
  53         t = time.time()
  54         self.instance.delete(key, value)
  55         this_time = time.time()-t
  56         self.total_time += this_time*1000
  57         self.deletes += 1
  58         self.calls.append((this_time, 'delete', (key,), self._get_func_info()))
  59
  60     def get_many(self, keys):
  61         t = time.time()
  62         results = self.cache.get_many(keys)
  63         this_time = time.time()-t
  64         self.total_time += this_time*1000
  65         self.get_many += 1
  66         for key, value in results.iteritems():
  67             if value is None:
  68                 self.misses += 1
  69             else:
  70                 self.hits += 1
  71         self.calls.append((this_time, 'get_many', (keys,), self._get_func_info()))
  72
  73 class CacheDebugPanel(DebugPanel):
  74     """
  75     Panel that displays the cache statistics.
  76     """
  77     name = 'Cache'
  78
  79     def __init__(self, request):
  80         # This is hackish but to prevent threading issues
  81         # is somewhat needed
  82         if isinstance(cache.cache, CacheStatTracker):
  83             cache.cache.reset()
  84             self.cache = cache.cache
  85         else:
  86             self.cache = CacheStatTracker(cache.cache)
  87             cache.cache = self.cache
  88         super(CacheDebugPanel, self).__init__(request)
  89
  90     def title(self):
  91         return 'Cache: %.2fms' % self.cache.total_time
  92
  93     def url(self):
  94         return ''
  95
  96     def content(self):
  97         context = dict(
  98             cache_calls = len(self.cache.calls),
  99             cache_time = self.cache.total_time,
 100             cache = self.cache,
 101         )
 102         return render_to_string('debug_toolbar/panels/cache.html', context)