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"""Daemon that processes commands"""
import os
import sys
import time
import logging
import argparse
import redis
import redis.connection
# Enable importing from one dir up: put as first to override any other globally
# accessible GN3
sys.path.insert(0, os.path.abspath(
os.path.join(os.path.dirname(__file__), '..')))
logging.basicConfig(
format=("%(asctime)s — %(filename)s:%(lineno)s — %(levelname)s: "
"CommandWorker: %(message)s"))
logger = logging.getLogger(__name__)
def update_status(conn, cmd_id, status):
"""Helper to update command status"""
conn.hset(name=f"{cmd_id}", key="status", value=f"{status}")
def make_incremental_backoff(init_val: float = 0.1, maximum: int = 420):
"""
Returns a closure that can be used to increment the returned value up to
`maximum` or reset it to `init_val`.
"""
current = init_val
def __increment_or_reset__(command: str, value: float = 0.1):
nonlocal current
if command == "reset":
current = init_val
return current
if command == "increment":
current = min(current + abs(value), maximum)
return current
return current
return __increment_or_reset__
def run_jobs(conn, queue_name):
"""Process the redis using a redis connection, CONN"""
# pylint: disable=E0401, C0415
from gn3.commands import run_cmd
cmd_id = (conn.lpop(queue_name) or b'').decode("utf-8")
if bool(cmd_id):
cmd = conn.hget(name=cmd_id, key="cmd")
if cmd and (conn.hget(cmd_id, "status") == b"queued"):
logger.debug("Updating status for job '%s' to 'running'", cmd_id)
update_status(conn, cmd_id, "running")
result = run_cmd(
cmd.decode("utf-8"), env=conn.hget(name=cmd_id, key="env"))
conn.hset(name=cmd_id, key="result", value=result.get("output"))
if result.get("code") == 0: # Success
update_status(conn, cmd_id, "success")
else:
update_status(conn, cmd_id, "error")
conn.hset(cmd_id, "stderr", result.get("output"))
return cmd_id
return None
def parse_cli_arguments():
"""Parse the command-line arguments."""
parser = argparse.ArgumentParser(
description="Run asynchronous (service) commands.")
parser.add_argument(
"--daemon", default=False, action="store_true",
help=(
"Run process as a daemon instead of the default 'one-shot' "
"process"))
parser.add_argument(
"--queue-name", default="GN3::job-queue", type=str,
help="The redis list that holds the unique command ids")
parser.add_argument(
"--log-level", default="info", type=str,
choices=("debug", "info", "warning", "error", "critical"),
help="What level to output the logs at.")
return parser.parse_args()
if __name__ == "__main__":
args = parse_cli_arguments()
logger.setLevel(args.log_level.upper())
logger.debug("Worker Script: Initialising worker")
with redis.Redis() as redis_conn:
if not args.daemon:
logger.info("Worker Script: Running worker in one-shot mode.")
run_jobs(redis_conn, args.queue_name)
logger.debug("Job completed!")
else:
logger.debug("Worker Script: Running worker in daemon-mode.")
sleep_time = make_incremental_backoff()
while True: # Daemon that keeps running forever:
if run_jobs(redis_conn, args.queue_name):
logger.debug("Ran a job. Pausing for a while...")
time.sleep(sleep_time("reset"))
continue
time.sleep(sleep_time(
"increment", sleep_time("return_current")))
logger.info("Worker exiting …")
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