Files
zulip/zephyr/lib/cache.py
Tim Abbott 9b8f0fab0f Retrieve message objects from memcached in a bulk request.
On my laptop, this saves about 80 milliseconds per 1000 messages
requested via get_old_messages queries.  Since we only have one
memcached process and it does not run with special priority, this
might have significant impact on load during server restarts.

(imported from commit 06ad13f32f4a6d87a0664c96297ef9843f410ac5)
2013-04-24 10:44:56 -04:00

120 lines
3.9 KiB
Python

from __future__ import absolute_import
from functools import wraps
from django.core.cache import cache as djcache
from django.core.cache import get_cache
from zephyr.lib.utils import statsd, statsd_key, make_safe_digest
import time
memcached_total_time = 0
memcached_total_requests = 0
def get_memcached_time():
return memcached_total_time
def get_memcached_requests():
return memcached_total_requests
def cache_with_key(keyfunc, cache_name=None, timeout=None):
"""Decorator which applies Django caching to a function.
Decorator argument is a function which computes a cache key
from the original function's arguments. You are responsible
for avoiding collisions with other uses of this decorator or
other uses of caching."""
def decorator(func):
@wraps(func)
def func_with_caching(*args, **kwargs):
global memcached_total_time
global memcached_total_requests
memcached_start = time.time()
if cache_name is None:
cache_backend = djcache
else:
cache_backend = get_cache(cache_name)
key = keyfunc(*args, **kwargs)
val = cache_backend.get(key)
memcached_total_requests += 1
memcached_total_time += (time.time() - memcached_start)
if val is not None:
statsd.incr("cache.%s.hit" % (statsd_key(key),))
else:
statsd.incr("cache.%s.miss" % (statsd_key(key),))
# Values are singleton tuples so that we can distinguish
# a result of None from a missing key.
if val is not None:
return val[0]
val = func(*args, **kwargs)
memcached_start = time.time()
cache_backend.set(key, (val,), timeout=timeout)
memcached_total_requests += 1
memcached_total_time += (time.time() - memcached_start)
return val
return func_with_caching
return decorator
def cache_get_many(keys, cache_name=None):
if cache_name is None:
cache_backend = djcache
else:
cache_backend = get_cache(cache_name)
return cache_backend.get_many(keys)
def cache(func):
"""Decorator which applies Django caching to a function.
Uses a key based on the function's name, filename, and
the repr() of its arguments."""
func_uniqifier = '%s-%s' % (func.func_code.co_filename, func.func_name)
@wraps(func)
def keyfunc(*args, **kwargs):
# Django complains about spaces because memcached rejects them
key = func_uniqifier + repr((args, kwargs))
return key.replace('-','--').replace(' ','-s')
return cache_with_key(keyfunc)(func)
def message_cache_key(message_id):
return "message:%d" % (message_id,)
def user_profile_by_email_cache_key(email):
# See the comment in zephyr/lib/avatar.py:gravatar_hash for why we
# are proactively encoding email addresses even though they will
# with high likelihood be ASCII-only for the foreseeable future.
return 'user_profile_by_email:%s' % (make_safe_digest(email),)
def user_profile_by_id_cache_key(user_profile_id):
return "user_profile_by_id:%s" % (user_profile_id,)
# Called by models.py to flush the user_profile cache whenever we save
# a user_profile object
def update_user_profile_cache(sender, **kwargs):
user_profile = kwargs['instance']
items_for_memcached = {}
items_for_memcached[user_profile_by_email_cache_key(user_profile.email)] = (user_profile,)
items_for_memcached[user_profile_by_id_cache_key(user_profile.id)] = (user_profile,)
djcache.set_many(items_for_memcached)
def status_dict_cache_key(user_profile):
return "status_dict:%d" % (user_profile.realm_id,)
def update_user_presence_cache(sender, **kwargs):
user_profile = kwargs['instance'].user_profile
djcache.delete(status_dict_cache_key(user_profile))