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import time
import inspect
try:
from cStringIO import StringIO
except ImportError:
import StringIO
from django.core import cache
from django.core.cache.backends.base import BaseCache
from django.template.loader import render_to_string
from debug_toolbar.panels import DebugPanel
class CacheStatTracker(BaseCache):
"""A small class used to track cache calls."""
def __init__(self, cache):
self.cache = cache
self.reset()
def reset(self):
self.calls = []
self.hits = 0
self.misses = 0
self.sets = 0
self.gets = 0
self.get_many = 0
self.deletes = 0
self.total_time = 0
def _get_func_info(self):
stack = inspect.stack()[2]
return (stack[1], stack[2], stack[3], stack[4])
def get(self, key, default=None):
t = time.time()
value = self.cache.get(key, default)
this_time = time.time() - t
self.total_time += this_time * 1000
if value is None:
self.misses += 1
else:
self.hits += 1
self.gets += 1
self.calls.append((this_time, 'get', (key,), self._get_func_info()))
return value
def set(self, key, value, timeout=None):
t = time.time()
self.cache.set(key, value, timeout)
this_time = time.time() - t
self.total_time += this_time * 1000
self.sets += 1
self.calls.append((this_time, 'set', (key, value, timeout), self._get_func_info()))
def delete(self, key):
t = time.time()
self.instance.delete(key, value)
this_time = time.time() - t
self.total_time += this_time * 1000
self.deletes += 1
self.calls.append((this_time, 'delete', (key,), self._get_func_info()))
def get_many(self, keys):
t = time.time()
results = self.cache.get_many(keys)
this_time = time.time() - t
self.total_time += this_time * 1000
self.get_many += 1
for key, value in results.iteritems():
if value is None:
self.misses += 1
else:
self.hits += 1
self.calls.append((this_time, 'get_many', (keys,), self._get_func_info()))
class CacheDebugPanel(DebugPanel):
"""
Panel that displays the cache statistics.
"""
name = 'Cache'
has_content = True
def __init__(self):
# This is hackish but to prevent threading issues is somewhat needed
if isinstance(cache.cache, CacheStatTracker):
cache.cache.reset()
self.cache = cache.cache
else:
self.cache = CacheStatTracker(cache.cache)
cache.cache = self.cache
def nav_title(self):
return 'Cache: %.2fms' % self.cache.total_time
def title(self):
return 'Cache Usage'
def url(self):
return ''
def content(self):
context = dict(
cache_calls = len(self.cache.calls),
cache_time = self.cache.total_time,
cache = self.cache,
)
return render_to_string('debug_toolbar/panels/cache.html', context)
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