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# -*- coding: utf-8 -*-
# Copyright 2018 New Vector
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from twisted.internet import defer
from synapse.util.caches.descriptors import cached
from ._base import SQLBaseStore
logger = logging.getLogger(__name__)
# Number of msec of granularity to store the monthly_active_user timestamp
# This means it is not necessary to update the table on every request
LAST_SEEN_GRANULARITY = 60 * 60 * 1000
class MonthlyActiveUsersStore(SQLBaseStore):
def __init__(self, dbconn, hs):
super(MonthlyActiveUsersStore, self).__init__(None, hs)
self._clock = hs.get_clock()
self.hs = hs
self.reserved_users = ()
@defer.inlineCallbacks
def initialise_reserved_users(self, threepids):
# TODO Why can't I do this in init?
store = self.hs.get_datastore()
reserved_user_list = []
# Do not add more reserved users than the total allowable number
for tp in threepids[:self.hs.config.max_mau_value]:
user_id = yield store.get_user_id_by_threepid(
tp["medium"], tp["address"]
)
if user_id:
yield self.upsert_monthly_active_user(user_id)
reserved_user_list.append(user_id)
else:
logger.warning(
"mau limit reserved threepid %s not found in db" % tp
)
self.reserved_users = tuple(reserved_user_list)
@defer.inlineCallbacks
def reap_monthly_active_users(self):
"""
Cleans out monthly active user table to ensure that no stale
entries exist.
Returns:
Deferred[]
"""
def _reap_users(txn):
# Purge stale users
thirty_days_ago = (
int(self._clock.time_msec()) - (1000 * 60 * 60 * 24 * 30)
)
query_args = [thirty_days_ago]
base_sql = "DELETE FROM monthly_active_users WHERE timestamp < ?"
# Need if/else since 'AND user_id NOT IN ({})' fails on Postgres
# when len(reserved_users) == 0. Works fine on sqlite.
if len(self.reserved_users) > 0:
# questionmarks is a hack to overcome sqlite not supporting
# tuples in 'WHERE IN %s'
questionmarks = '?' * len(self.reserved_users)
query_args.extend(self.reserved_users)
sql = base_sql + """ AND user_id NOT IN ({})""".format(
','.join(questionmarks)
)
else:
sql = base_sql
txn.execute(sql, query_args)
# If MAU user count still exceeds the MAU threshold, then delete on
# a least recently active basis.
# Note it is not possible to write this query using OFFSET due to
# incompatibilities in how sqlite and postgres support the feature.
# sqlite requires 'LIMIT -1 OFFSET ?', the LIMIT must be present
# While Postgres does not require 'LIMIT', but also does not support
# negative LIMIT values. So there is no way to write it that both can
# support
safe_guard = self.hs.config.max_mau_value - len(self.reserved_users)
# Must be greater than zero for postgres
safe_guard = safe_guard if safe_guard > 0 else 0
query_args = [safe_guard]
base_sql = """
DELETE FROM monthly_active_users
WHERE user_id NOT IN (
SELECT user_id FROM monthly_active_users
ORDER BY timestamp DESC
LIMIT ?
)
"""
# Need if/else since 'AND user_id NOT IN ({})' fails on Postgres
# when len(reserved_users) == 0. Works fine on sqlite.
if len(self.reserved_users) > 0:
query_args.extend(self.reserved_users)
sql = base_sql + """ AND user_id NOT IN ({})""".format(
','.join(questionmarks)
)
else:
sql = base_sql
txn.execute(sql, query_args)
yield self.runInteraction("reap_monthly_active_users", _reap_users)
# It seems poor to invalidate the whole cache, Postgres supports
# 'Returning' which would allow me to invalidate only the
# specific users, but sqlite has no way to do this and instead
# I would need to SELECT and the DELETE which without locking
# is racy.
# Have resolved to invalidate the whole cache for now and do
# something about it if and when the perf becomes significant
self.user_last_seen_monthly_active.invalidate_all()
self.get_monthly_active_count.invalidate_all()
@cached(num_args=0)
def get_monthly_active_count(self):
"""Generates current count of monthly active users
Returns:
Defered[int]: Number of current monthly active users
"""
def _count_users(txn):
sql = "SELECT COALESCE(count(*), 0) FROM monthly_active_users"
txn.execute(sql)
count, = txn.fetchone()
return count
return self.runInteraction("count_users", _count_users)
def upsert_monthly_active_user(self, user_id):
"""
Updates or inserts monthly active user member
Arguments:
user_id (str): user to add/update
Deferred[bool]: True if a new entry was created, False if an
existing one was updated.
"""
is_insert = self._simple_upsert(
desc="upsert_monthly_active_user",
table="monthly_active_users",
keyvalues={
"user_id": user_id,
},
values={
"timestamp": int(self._clock.time_msec()),
},
lock=False,
)
if is_insert:
self.user_last_seen_monthly_active.invalidate((user_id,))
self.get_monthly_active_count.invalidate(())
@cached(num_args=1)
def user_last_seen_monthly_active(self, user_id):
"""
Checks if a given user is part of the monthly active user group
Arguments:
user_id (str): user to add/update
Return:
Deferred[int] : timestamp since last seen, None if never seen
"""
return(self._simple_select_one_onecol(
table="monthly_active_users",
keyvalues={
"user_id": user_id,
},
retcol="timestamp",
allow_none=True,
desc="user_last_seen_monthly_active",
))
@defer.inlineCallbacks
def populate_monthly_active_users(self, user_id):
"""Checks on the state of monthly active user limits and optionally
add the user to the monthly active tables
Args:
user_id(str): the user_id to query
"""
if self.hs.config.limit_usage_by_mau:
last_seen_timestamp = yield self.user_last_seen_monthly_active(user_id)
now = self.hs.get_clock().time_msec()
# We want to reduce to the total number of db writes, and are happy
# to trade accuracy of timestamp in order to lighten load. This means
# We always insert new users (where MAU threshold has not been reached),
# but only update if we have not previously seen the user for
# LAST_SEEN_GRANULARITY ms
if last_seen_timestamp is None:
count = yield self.get_monthly_active_count()
if count < self.hs.config.max_mau_value:
yield self.upsert_monthly_active_user(user_id)
elif now - last_seen_timestamp > LAST_SEEN_GRANULARITY:
yield self.upsert_monthly_active_user(user_id)
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