python_pinger.git

1) #!/usr/bin/python3
2) #
3) # Since this is meant to be run as a daemon, do not use #!/usr/bin/env python3,
4) # because the process name would then be python3, not based on __FILE__.
5) #
6) # [filename] -d 3 192.168.1.1 192.168.1.12 &
7) # disown [jobid]
8) import os
9) import sys
10) import subprocess
11) import time
12) from argparse import ArgumentParser
13) import threading
14) import queue

15) import signal

16) from typing import Dict, Optional

17) 

18) pinger_lock = threading.Lock()
19) 

20) 

21) def log_exit(sig: int, frame) -> None:

22)     _print_queue.put([f'{time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())} '
23)                       f'PID={os.getpid()} signal={signal.Signals(sig).name} Exiting.'])

24)     _print_queue.join()
25)     sys.exit(0)
26) 
27) 

28) def pinger() -> None:

29)     """Each queue item is a new address to ping. Ping and compare and print.
30)     Issue: Each of these threads reads from and writes to the global _results dict.
31)     """
32)     while True:
33)         host = _ping_queue.get()
34)         now = time.localtime()
35)         success = ping(host)

36)         with pinger_lock:
37)             # Access to _results needs to be serialized
38)             need_update = success != _results[host]
39)             if need_update:
40)                 _results[host] = success
41)         if need_update:

42)             status = "UP" if success else "DOWN"
43)             _print_queue.put([f'{time.strftime("%Y-%m-%d %H:%M:%S", now)} {host} {status}'])
44)         _ping_queue.task_done()
45) 
46) 

47) def ping(host: str) -> int:

48)     """Returns True if host (str) responds to a ping request."""
49)     return subprocess.call([*_ping_cmd, host], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) == 0
50) 
51) 

52) def print_manager() -> None:

53)     """The only thread allowed to write output."""
54)     while True:
55)         job = _print_queue.get()
56)         for line in job:
57)             log(line)
58)         _print_queue.task_done()
59) 
60) 

61) def log(*args, **kwargs) -> None:

62)     """Opens the logfile, writes the log, and closes the logfile."""
63)     # I don't leave the log file open for writing because another process needs access too.
64)     with open(_logname, 'a') as fp:

65)         print(*args, **kwargs, file=fp)

66) 
67) 
68) if __name__ == '__main__':
69)     parser = ArgumentParser(description="Repeatedly ping sites. Ex: %(prog)s -d 3 192.168.1.1 192.168.1.12")
70)     parser.add_argument('-d', '--delay', type=float, default=1.0, help='Delay between pings')
71)     parser.add_argument('addresses', nargs='+', help='Addresses to ping')
72)     parser_args = parser.parse_args()
73) 

74)     _results: Dict[str, Optional[int]] = dict()

75)     for addr in parser_args.addresses:
76)         _results[addr] = None
77)     delay = parser_args.delay
78) 
79)     _ping_queue = queue.Queue(2 * len(parser_args.addresses))  # No more than 2 pending pings per address
80)     _print_queue = queue.Queue()
81) 
82)     _logname = os.path.join(os.path.expanduser('~'), 'log', os.path.basename(sys.argv[0]).replace('py', 'txt'))
83)     _pid = os.getpid()
84) 
85)     # Choose the ping parameters appropriate for the platform
86)     if sys.platform == 'cygwin' or sys.platform == 'win32':
87)         _ping_cmd = ('ping', '-n', '1', '-w', '2000')
88)     else:
89)         _ping_cmd = ('ping', '-c', '1', '-W', '2', '-q')
90) 
91)     for i in range(len(parser_args.addresses)):
92)         t = threading.Thread(target=pinger, daemon=True)
93)         t.start()
94)         del t
95) 
96)     t = threading.Thread(target=print_manager, daemon=True)
97)     t.start()
98)     del t
99) 
100)     _print_queue.put([f'{time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())}'

101)         f' PID={os.getpid()} repeat={delay}s addresses={",".join(parser_args.addresses)} Starting'])
102) 
103)     signal.signal(signal.SIGINT, log_exit)
104)     signal.signal(signal.SIGTERM, log_exit)
105)