zulip/zerver/worker/user_activity.py

85 lines
3.3 KiB
Python
Raw Normal View History

# Documented in https://zulip.readthedocs.io/en/latest/subsystems/queuing.html
import logging
from typing import Any, Dict, List, Tuple
from django.db import connection
from psycopg2.sql import SQL, Literal
from typing_extensions import override
from zerver.worker.base import LoopQueueProcessingWorker, assign_queue
logger = logging.getLogger(__name__)
@assign_queue("user_activity")
class UserActivityWorker(LoopQueueProcessingWorker):
"""The UserActivity queue is perhaps our highest-traffic queue, and
requires some care to ensure it performs adequately.
We use a LoopQueueProcessingWorker as a performance optimization
for managing the queue. The structure of UserActivity records is
such that they are easily deduplicated before being sent to the
database; we take advantage of that to make this queue highly
effective at dealing with a backlog containing many similar
events. Such a backlog happen in a few ways:
* In abuse/DoS situations, if a client is sending huge numbers of
similar requests to the server.
* If the queue ends up with several minutes of backlog e.g. due to
downtime of the queue processor, many clients will have several
common events from doing an action multiple times.
"""
client_id_map: Dict[str, int] = {}
@override
def start(self) -> None:
# For our unit tests to make sense, we need to clear this on startup.
self.client_id_map = {}
super().start()
@override
def consume_batch(self, user_activity_events: List[Dict[str, Any]]) -> None:
uncommitted_events: Dict[Tuple[int, int, str], Tuple[int, float]] = {}
# First, we drain the queue of all user_activity events and
# deduplicate them for insertion into the database.
for event in user_activity_events:
user_profile_id = event["user_profile_id"]
client_id = event["client_id"]
key_tuple = (user_profile_id, client_id, event["query"])
if key_tuple not in uncommitted_events:
uncommitted_events[key_tuple] = (1, event["time"])
else:
count, event_time = uncommitted_events[key_tuple]
uncommitted_events[key_tuple] = (count + 1, max(event_time, event["time"]))
rows = []
for key_tuple, value_tuple in uncommitted_events.items():
user_profile_id, client_id, query = key_tuple
count, event_time = value_tuple
rows.append(
SQL("({},{},{},{},to_timestamp({}))").format(
Literal(user_profile_id),
Literal(client_id),
Literal(query),
Literal(count),
Literal(event_time),
)
)
# Perform a single bulk UPSERT for all of the rows
sql_query = SQL(
"""
INSERT INTO zerver_useractivity(user_profile_id, client_id, query, count, last_visit)
VALUES {rows}
ON CONFLICT (user_profile_id, client_id, query) DO UPDATE SET
count = zerver_useractivity.count + excluded.count,
last_visit = greatest(zerver_useractivity.last_visit, excluded.last_visit)
"""
).format(rows=SQL(", ").join(rows))
with connection.cursor() as cursor:
cursor.execute(sql_query)