searxng/searx/search/checker/scheduler.py
Markus Heiser 542f7d0d7b [mod] pylint all files with one profile / drop PYLINT_SEARXNG_DISABLE_OPTION
In the past, some files were tested with the standard profile, others with a
profile in which most of the messages were switched off ... some files were not
checked at all.

- ``PYLINT_SEARXNG_DISABLE_OPTION`` has been abolished
- the distinction ``# lint: pylint`` is no longer necessary
- the pylint tasks have been reduced from three to two

  1. ./searx/engines -> lint engines with additional builtins
  2. ./searx ./searxng_extra ./tests -> lint all other python files

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
2024-03-11 14:55:38 +01:00

59 lines
2.5 KiB
Python

# SPDX-License-Identifier: AGPL-3.0-or-later
# pylint: disable=missing-module-docstring
"""Lame scheduler which use Redis as a source of truth:
* the Redis key SearXNG_checker_next_call_ts contains the next time the embedded checker should run.
* to avoid lock, a unique Redis script reads and updates the Redis key SearXNG_checker_next_call_ts.
* this Redis script returns a list of two elements:
* the first one is a boolean. If True, the embedded checker must run now in this worker.
* the second element is the delay in second to wait before the next call to the Redis script.
This scheduler is not generic on purpose: if more feature are required, a dedicate scheduler must be used
(= a better scheduler should not use the web workers)
"""
import logging
import time
from pathlib import Path
from typing import Callable
from searx.redisdb import client as get_redis_client
from searx.redislib import lua_script_storage
logger = logging.getLogger('searx.search.checker')
SCHEDULER_LUA = Path(__file__).parent / "scheduler.lua"
def scheduler_function(start_after_from: int, start_after_to: int, every_from: int, every_to: int, callback: Callable):
"""Run the checker periodically. The function never returns.
Parameters:
* start_after_from and start_after_to: when to call "callback" for the first on the Redis instance
* every_from and every_to: after the first call, how often to call "callback"
There is no issue:
* to call this function is multiple workers
* to kill workers at any time as long there is one at least one worker
"""
scheduler_now_script = SCHEDULER_LUA.open().read()
while True:
# ask the Redis script what to do
# the script says
# * if the checker must run now.
# * how to long to way before calling the script again (it can be call earlier, but not later).
script = lua_script_storage(get_redis_client(), scheduler_now_script)
call_now, wait_time = script(args=[start_after_from, start_after_to, every_from, every_to])
# does the worker run the checker now?
if call_now:
# run the checker
try:
callback()
except Exception: # pylint: disable=broad-except
logger.exception("Error calling the embedded checker")
# only worker display the wait_time
logger.info("Next call to the checker in %s seconds", wait_time)
# wait until the next call
time.sleep(wait_time)