fdba41c682
* perf: Reduce penalty for lack of redis connection If redis isn't running than this client cache is slower than default implementation because of the extra locking overhead. * test: update perf redis counts * perf: cache table columns in client-cache * fix: race condition on cache-client_cache init Rare but apparant in synthetic benchmarks. Cache is set but client cache is still being initialized then request will fail. * perf: Don't run notifications when loading document WHAT? * fix: use cached doc to repopulate * perf: reduce get_meta calls
599 lines
17 KiB
Python
599 lines
17 KiB
Python
# Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
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# License: MIT. See LICENSE
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import pickle
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import re
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import threading
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import time
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import typing
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from collections import namedtuple
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from contextlib import suppress
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import redis
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from redis.commands.search import Search
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import frappe
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from frappe.utils import cstr
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from frappe.utils.data import cint
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# 5 is faster than default which is 4.
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# Python uses old protocol for backward compatibility, we don't support anything <3.10.
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DEFAULT_PICKLE_PROTOCOL = 5
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class RedisearchWrapper(Search):
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def sugadd(self, key, *suggestions, **kwargs):
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return super().sugadd(self.client.make_key(key), *suggestions, **kwargs)
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def suglen(self, key):
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return super().suglen(self.client.make_key(key))
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def sugdel(self, key, string):
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return super().sugdel(self.client.make_key(key), string)
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def sugget(self, key, *args, **kwargs):
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return super().sugget(self.client.make_key(key), *args, **kwargs)
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class RedisWrapper(redis.Redis):
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"""Redis client that will automatically prefix conf.db_name"""
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def connected(self):
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try:
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self.ping()
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return True
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except redis.exceptions.ConnectionError:
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return False
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def __call__(self):
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"""WARNING: Added for backward compatibility to support frappe.cache().method(...)"""
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return self
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def make_key(self, key, user=None, shared=False):
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if shared:
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return key
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if user:
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if user is True:
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user = frappe.session.user
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key = f"user:{user}:{key}"
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return f"{frappe.conf.db_name}|{key}".encode()
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def set_value(self, key, val, user=None, expires_in_sec=None, shared=False):
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"""Sets cache value.
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:param key: Cache key
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:param val: Value to be cached
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:param user: Prepends key with User
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:param expires_in_sec: Expire value of this key in X seconds
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"""
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key = self.make_key(key, user, shared)
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frappe.local.cache[key] = val
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with suppress(redis.exceptions.ConnectionError):
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self.set(name=key, value=pickle.dumps(val, protocol=DEFAULT_PICKLE_PROTOCOL), ex=expires_in_sec)
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def get_value(self, key, generator=None, user=None, expires=False, shared=False, *, use_local_cache=True):
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"""Return cache value. If not found and generator function is
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given, call the generator.
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:param key: Cache key.
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:param generator: Function to be called to generate a value if `None` is returned.
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:param expires: If the key is supposed to be with an expiry, don't store it in frappe.local
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"""
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original_key = key
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key = self.make_key(key, user, shared)
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local_cache = frappe.local.cache
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if key in local_cache and use_local_cache:
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val = local_cache[key]
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else:
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val = None
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try:
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val = self.get(key)
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except redis.exceptions.ConnectionError:
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pass
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if val is not None:
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val = pickle.loads(val)
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if not expires:
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if val is None and generator:
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val = generator()
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self.set_value(original_key, val, user=user)
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else:
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local_cache[key] = val
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return val
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def get_all(self, key):
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ret = {}
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for k in self.get_keys(key):
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ret[key] = self.get_value(k)
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return ret
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def get_keys(self, key):
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"""Return keys starting with `key`."""
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try:
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key = self.make_key(key + "*")
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return self.keys(key)
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except redis.exceptions.ConnectionError:
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regex = re.compile(cstr(key).replace("|", r"\|").replace("*", r"[\w]*"))
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return [k for k in list(frappe.local.cache) if regex.match(cstr(k))]
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def delete_keys(self, key):
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"""Delete keys with wildcard `*`."""
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self.delete_value(self.get_keys(key), make_keys=False)
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def delete_key(self, *args, **kwargs):
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self.delete_value(*args, **kwargs)
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def delete_value(self, keys, user=None, make_keys=True, shared=False):
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"""Delete value, list of values."""
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if not keys:
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return
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if not isinstance(keys, list | tuple):
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keys = (keys,)
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if make_keys:
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keys = [self.make_key(k, shared=shared, user=user) for k in keys]
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local_cache = frappe.local.cache
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for key in keys:
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local_cache.pop(key, None)
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try:
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self.unlink(*keys)
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except redis.exceptions.ConnectionError:
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pass
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def lpush(self, key, value):
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return super().lpush(self.make_key(key), value)
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def rpush(self, key, value):
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return super().rpush(self.make_key(key), value)
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def lpop(self, key):
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return super().lpop(self.make_key(key))
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def rpop(self, key):
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return super().rpop(self.make_key(key))
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def llen(self, key):
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return super().llen(self.make_key(key))
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def lrange(self, key, start, stop):
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return super().lrange(self.make_key(key), start, stop)
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def ltrim(self, key, start, stop):
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return super().ltrim(self.make_key(key), start, stop)
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def hset(
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self,
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name: str,
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key: str,
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value,
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shared: bool = False,
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*args,
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**kwargs,
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):
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if key is None:
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return
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_name = self.make_key(name, shared=shared)
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# set in local
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frappe.local.cache.setdefault(_name, {})[key] = value
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# set in redis
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try:
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super().hset(_name, key, pickle.dumps(value, protocol=DEFAULT_PICKLE_PROTOCOL), *args, **kwargs)
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except redis.exceptions.ConnectionError:
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pass
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def hexists(self, name: str, key: str, shared: bool = False) -> bool:
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if key is None:
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return False
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_name = self.make_key(name, shared=shared)
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try:
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return super().hexists(_name, key)
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except redis.exceptions.ConnectionError:
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return False
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def exists(self, *names: str, user=None, shared=None) -> int:
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names = [self.make_key(n, user=user, shared=shared) for n in names]
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try:
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return super().exists(*names)
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except redis.exceptions.ConnectionError:
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return False
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def hgetall(self, name):
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value = super().hgetall(self.make_key(name))
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return {key: pickle.loads(value) for key, value in value.items()}
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def hget(self, name, key, generator=None, shared=False):
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_name = self.make_key(name, shared=shared)
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local_cache = frappe.local.cache
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if _name not in local_cache:
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local_cache[_name] = {}
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if not key:
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return None
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if key in local_cache[_name]:
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return local_cache[_name][key]
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value = None
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try:
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value = super().hget(_name, key)
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except redis.exceptions.ConnectionError:
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pass
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if value is not None:
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value = pickle.loads(value)
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local_cache[_name][key] = value
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elif generator:
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value = generator()
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self.hset(name, key, value, shared=shared)
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return value
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def hdel(
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self,
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name: str,
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keys: str | list | tuple,
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shared=False,
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pipeline: redis.client.Pipeline | None = None,
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):
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"""
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A wrapper around redis' HDEL command
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:param name: The hash name
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:param keys: the keys to delete
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:param shared: shared frappe key or not
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:param pipeline: A redis.client.Pipeline object, if this transaction is to be run in a pipeline
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"""
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_name = self.make_key(name, shared=shared)
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name_in_local_cache = _name in frappe.local.cache
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if not isinstance(keys, list | tuple):
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if name_in_local_cache and keys in frappe.local.cache[_name]:
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del frappe.local.cache[_name][keys]
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if pipeline:
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pipeline.hdel(_name, keys)
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else:
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try:
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super().hdel(_name, keys)
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except redis.exceptions.ConnectionError:
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pass
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return
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local_pipeline = False
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if pipeline is None:
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pipeline = self.pipeline()
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local_pipeline = True
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for key in keys:
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if name_in_local_cache:
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if key in frappe.local.cache[_name]:
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del frappe.local.cache[_name][key]
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pipeline.hdel(_name, key)
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if local_pipeline:
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try:
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pipeline.execute()
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except redis.exceptions.ConnectionError:
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pass
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def hdel_names(self, names: list | tuple, key: str):
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"""
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A function to call HDEL on multiple hash names with a common key, run in a single pipeline
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:param names: The hash names
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:param key: The common key
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"""
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pipeline = self.pipeline()
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for name in names:
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self.hdel(name, key, pipeline=pipeline)
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try:
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pipeline.execute()
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except redis.exceptions.ConnectionError:
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pass
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def hdel_keys(self, name_starts_with, key):
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"""Delete hash names with wildcard `*` and key"""
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pipeline = self.pipeline()
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for name in self.get_keys(name_starts_with):
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name = name.split("|", 1)[1]
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self.hdel(name, key, pipeline=pipeline)
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try:
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pipeline.execute()
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except redis.exceptions.ConnectionError:
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pass
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def hkeys(self, name):
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try:
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return super().hkeys(self.make_key(name))
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except redis.exceptions.ConnectionError:
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return []
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def sadd(self, name, *values):
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"""Add a member/members to a given set"""
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super().sadd(self.make_key(name), *values)
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def srem(self, name, *values):
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"""Remove a specific member/list of members from the set."""
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super().srem(self.make_key(name), *values)
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def sismember(self, name, value):
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"""Return True or False based on if a given value is present in the set."""
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return super().sismember(self.make_key(name), value)
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def spop(self, name):
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"""Remove and returns a random member from the set."""
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return super().spop(self.make_key(name))
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def srandmember(self, name, count=None):
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"""Return a random member from the set."""
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return super().srandmember(self.make_key(name))
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def smembers(self, name):
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"""Return all members of the set."""
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return super().smembers(self.make_key(name))
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def ft(self, index_name="idx"):
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return RedisearchWrapper(client=self, index_name=self.make_key(index_name))
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def setup_cache() -> RedisWrapper:
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if frappe.conf.redis_cache_sentinel_enabled:
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sentinels = [tuple(node.split(":")) for node in frappe.conf.get("redis_cache_sentinels", [])]
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sentinel = get_sentinel_connection(
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sentinels=sentinels,
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sentinel_username=frappe.conf.get("redis_cache_sentinel_username"),
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sentinel_password=frappe.conf.get("redis_cache_sentinel_password"),
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master_username=frappe.conf.get("redis_cache_master_username"),
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master_password=frappe.conf.get("redis_cache_master_password"),
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)
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return sentinel.master_for(
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frappe.conf.get("redis_cache_master_service"),
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redis_class=RedisWrapper,
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)
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return RedisWrapper.from_url(frappe.conf.get("redis_cache"))
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def get_sentinel_connection(
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sentinels: list[tuple[str, int]],
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sentinel_username=None,
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sentinel_password=None,
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master_username=None,
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master_password=None,
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):
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from redis.sentinel import Sentinel
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sentinel_kwargs = {}
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if sentinel_username:
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sentinel_kwargs["username"] = sentinel_username
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if sentinel_password:
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sentinel_kwargs["password"] = sentinel_password
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return Sentinel(
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sentinels=sentinels,
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sentinel_kwargs=sentinel_kwargs,
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username=master_username,
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password=master_password,
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)
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class _TrackedConnection(redis.Connection):
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def __init__(self, *args, **kwargs):
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self._invalidator_id = kwargs.pop("_invalidator_id")
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super().__init__(*args, **kwargs)
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# Every redis connection needs to enable client tracking to get notified about invalidated
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# keys.
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self.register_connect_callback(self._enable_client_tracking)
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def _enable_client_tracking(self, conn):
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conn.send_command("CLIENT", "TRACKING", "ON", "redirect", self._invalidator_id, "NOLOOP")
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conn.read_response()
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CachedValue = namedtuple("CachedValue", ["value", "expiry"])
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CacheStatistics = namedtuple(
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"CacheStatistics", ["hits", "misses", "capacity", "used", "utilization", "hit_ratio", "healthy"]
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)
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_PLACEHOLDER_VALUE = CachedValue(value=None, expiry=-1)
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class ClientCache:
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"""A subset of RedisWrapper that keeps "local" cache across requests.
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Main reason for doing this is improving performance while reading things like hooks, schema.
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This feature is internal to Frappe Framework and is subjected to change without any notice.
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There aren't many use cases for such aggressive caching outside of core Framework.
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This is an implementation of Redis' "client side caching" concept:
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- https://redis.io/docs/latest/develop/reference/client-side-caching/
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Usage/Notes:
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- Cache keys that do not change often: Think hours-days, not minutes.
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- Cache keys that are read frequently, e.g. every request or at least >10% of the requests.
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- Cache values are not huge, consider avg size of ~4kb per value. You can deviate here and
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there but not go crazy with caching large values in this cache.
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- We have hardcoded 10 minutes "local" ttl and max 1024 keys.
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You're not supposed to work with these numbers, not change them.
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- Same keys can be accessed with `frappe.cache` too, but that won't implement invalidation.
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- Invalidate things as usual using `delete_value`. Local invalidation should be instant.
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Do not expect sub-second invalidation guarantees across processes.
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If you need that kind of guarantees, don't use this cache.
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- When redis connection isn't available or any unknown exceptions are encountered, this
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cache automatically turns itself off and falls back to behaviour that is equivalent to
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default Redis cache behaviour.
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- Never use `frappe.cache`'s request local cache along with client-side cache. Two
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different copies of same key are a big source of data races.
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- This cache uses simple FIFO eviction policy. Make sure your access patterns don't cause
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the worst case behaviour for this policy. E.g. looping over `maxsize` items repeatedly.
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"""
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def __init__(self, maxsize: int = 1024, ttl=10 * 60, monitor: RedisWrapper | None = None) -> None:
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self.maxsize = maxsize or 1024 # Expect 1024 * 4kb objects ~ 4MB
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self.local_ttl = ttl
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# This guards writes to self.cache, reads are done without a lock.
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self.lock = threading.RLock()
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self.cache: dict[bytes, CachedValue] = {}
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self.invalidator = frappe.cache
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self.healthy = True
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self.connection_retries = 0
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self.invalidator_id = None
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try:
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self.invalidator_id = self.invalidator.client_id()
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except redis.exceptions.ConnectionError:
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# Redis not available, this can happen during setup/startup time
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self.redis = frappe.cache
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self.healthy = False
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# These are local hits and misses, *not* global.
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# - Local miss = not found in worker memory
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# - Global miss = not found in Redis too
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# These stats can be *slightly* off, these aren't guarded by a mutex.
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self.hits = self.misses = 0
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if not self.invalidator_id:
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return
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self.redis: RedisWrapper = RedisWrapper.from_url(
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frappe.conf.get("redis_cache"),
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connection_class=_TrackedConnection,
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_invalidator_id=self.invalidator_id,
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protocol=2,
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)
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self.invalidator_thread = self.run_invalidator_thread()
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def get_value(self, key):
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if not self.healthy:
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return self.redis.get_value(key)
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key = self.redis.make_key(key)
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try:
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val = self.cache[key]
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if time.monotonic() < val.expiry and self.healthy:
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self.hits += 1
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return val.value
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except KeyError:
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pass
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self.misses += 1
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# Store a placeholder value to detect race between GET and parallel invalidation.
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with self.lock:
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self.cache[key] = _PLACEHOLDER_VALUE
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val = self.redis.get_value(key, shared=True, use_local_cache=not self.healthy)
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# Note: We should not "cache" the cache-misses in client cache.
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# This cache is long lived and "misses" are not tracked by redis so they'll never get
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# invalidated.
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if val is None:
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return None
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self.ensure_max_size()
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with self.lock:
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# Note: If our placeholder value is not present then it's possible that value we just
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# got is invalidated, so we should not store it in local cache.
|
|
if key in self.cache:
|
|
self.cache[key] = CachedValue(value=val, expiry=time.monotonic() + self.local_ttl)
|
|
|
|
return val
|
|
|
|
def set_value(self, key, val):
|
|
key = self.redis.make_key(key)
|
|
self.ensure_max_size()
|
|
self.redis.set_value(key, val, shared=True)
|
|
with self.lock:
|
|
self.cache[key] = CachedValue(value=val, expiry=time.monotonic() + self.local_ttl)
|
|
# XXX: We need to tell redis that we indeed read this key we just wrote
|
|
# This is an edge case:
|
|
# - Client A writes a key and reads it again from local cache
|
|
# - Client B overwrites this key, but since client A never "read" it from Redis, Redis
|
|
# doesn't send invalidation.
|
|
_ = self.redis.get_value(key, shared=True, use_local_cache=not self.healthy)
|
|
|
|
def ensure_max_size(self):
|
|
if len(self.cache) >= self.maxsize:
|
|
with self.lock, suppress(RuntimeError):
|
|
self.cache.pop(next(iter(self.cache)), None)
|
|
|
|
def delete_value(self, key):
|
|
key = self.redis.make_key(key)
|
|
self.redis.delete_value(key, shared=True)
|
|
with self.lock:
|
|
self.cache.pop(key, None)
|
|
|
|
def delete_keys(self, pattern):
|
|
keys = self.redis.get_keys(pattern)
|
|
self.redis.delete_value(keys, shared=True, make_keys=False)
|
|
with self.lock:
|
|
for key in keys:
|
|
self.cache.pop(key, None)
|
|
|
|
def run_invalidator_thread(self):
|
|
self._watcher = self.invalidator.pubsub()
|
|
self._watcher.subscribe(**{"__redis__:invalidate": self._handle_invalidation})
|
|
return self._watcher.run_in_thread(
|
|
sleep_time=None,
|
|
daemon=True,
|
|
exception_handler=self._exception_handler,
|
|
)
|
|
|
|
def _handle_invalidation(self, message):
|
|
if message["data"] is None:
|
|
# Flushall
|
|
self.clear_cache()
|
|
return
|
|
with self.lock:
|
|
for key in message["data"]:
|
|
self.cache.pop(key, None)
|
|
|
|
def _exception_handler(self, exc, pubsub, pubsub_thread):
|
|
if isinstance(exc, (redis.exceptions.ConnectionError)):
|
|
self.clear_cache()
|
|
self.connection_retries += 1
|
|
if self.connection_retries > 10:
|
|
self.healthy = False
|
|
raise
|
|
time.sleep(1)
|
|
else:
|
|
self.healthy = False
|
|
raise
|
|
|
|
def clear_cache(self):
|
|
with self.lock:
|
|
self.cache.clear()
|
|
|
|
@property
|
|
def statistics(self) -> CacheStatistics:
|
|
return CacheStatistics(
|
|
hits=self.hits,
|
|
misses=self.misses,
|
|
capacity=self.maxsize,
|
|
used=len(self.cache),
|
|
healthy=self.healthy,
|
|
utilization=round(len(self.cache) / self.maxsize, 2),
|
|
hit_ratio=round(self.hits / (self.hits + self.misses), 2) if self.hits else None,
|
|
)
|
|
|
|
def reset_statistics(self):
|
|
self.hits = self.misses = 0
|