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"""Daemon that processes commands"""
import os
import sys
import time
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__), '..')))
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: str = "GN3::job-queue"):
"""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"):
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")
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"))
return parser.parse_args()
if __name__ == "__main__":
args = parse_cli_arguments()
with redis.Redis() as redis_conn:
if not args.daemon:
run_jobs(redis_conn)
else:
sleep_time = make_incremental_backoff()
while True: # Daemon that keeps running forever:
if run_jobs(redis_conn):
time.sleep(sleep_time("reset"))
continue
time.sleep(sleep_time("increment", sleep_time("return_current")))
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