Schrolli91/BOSWatch
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prepare boswatch.py for use as a daemon

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1.) We had to change the subprocess calls, don't use shell=True if you want to run as daemon,
you will never be able to kill the sub-sub-processes
2.) implement signal-handler for TERM signal of the daemon-control
This commit is contained in:
JHCD 2015-06-24 23:26:02 +02:00
parent 3280c68737
commit 259239a90b
1 changed files with 36 additions and 8 deletions
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44
boswatch.py
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@ -21,6 +21,8 @@ import ConfigParser # for parse the config file
import os # for log mkdir
import time # for timestamp
import subprocess # for starting rtl_fm and multimon-ng
import signal # for use as daemon
import sys # throw SystemExitException when daemon is terminated
from includes import globals # Global variables
@ -58,6 +60,20 @@ def freqToHz(freq):
except:
logging.exception("Error in freqToHz()")
##
#
# TERM-Handler for use script as a daemon
# In order for the Python program to exit gracefully when the TERM signal is received,
# it must have a function that exits the program when signal.SIGTERM is received.
#
def sigterm_handler(_signo, _stack_frame):
import sys
global logging
logging.warning("TERM signal received")
sys.exit(0)
signal.signal(signal.SIGTERM, sigterm_handler)
#
# ArgParser
@ -245,11 +261,12 @@ try:
# Start rtl_fm
#
logging.debug("starting rtl_fm")
rtl_fm = subprocess.Popen("rtl_fm -d "+str(args.device)+" -f "+str(freqToHz(args.freq))+" -M fm -s 22050 -p "+str(args.error)+" -E DC -F 0 -l "+str(args.squelch)+" -g 100",
command = "rtl_fm -d "+str(args.device)+" -f "+str(freqToHz(args.freq))+" -M fm -s 22050 -p "+str(args.error)+" -E DC -F 0 -l "+str(args.squelch)+" -g 100"
rtl_fm = subprocess.Popen(command.split(),
#stdin=rtl_fm.stdout,
stdout=subprocess.PIPE,
stderr=open(globals.script_path+"/log/rtl_fm.log","a"),
shell=True)
shell=False)
except:
logging.exception("cannot start rtl_fm")
else:
@ -260,11 +277,12 @@ try:
# Start multimon
#
logging.debug("starting multimon-ng")
multimon_ng = subprocess.Popen("multimon-ng "+str(demodulation)+" -f alpha -t raw /dev/stdin - ",
command = "multimon-ng "+str(demodulation)+" -f alpha -t raw /dev/stdin - "
multimon_ng = subprocess.Popen(command.split(),
stdin=rtl_fm.stdout,
stdout=subprocess.PIPE,
stderr=open(globals.script_path+"/log/multimon.log","a"),
shell=True)
shell=False)
except:
logging.exception("cannot start multimon-ng")
else:
@ -298,18 +316,28 @@ try:
except KeyboardInterrupt:
logging.warning("Keyboard Interrupt")
except SystemExit:
# SystemExitException is thrown if daemon was terminated
logging.warning("SystemExit received")
# only exit to call finally-block
exit(0)
except:
logging.exception("unknown error")
finally:
try:
logging.debug("BOSWatch shuting down")
rtl_fm.terminate()
logging.debug("rtl_fm terminated")
logging.debug("terminate multimon-ng (%s)", multimon_ng.pid)
multimon_ng.terminate()
multimon_ng.wait()
logging.debug("multimon-ng terminated")
logging.debug("terminate rtl_fm (%s)", rtl_fm.pid)
rtl_fm.terminate()
rtl_fm.wait()
logging.debug("rtl_fm terminated")
logging.debug("exiting BOSWatch")
except:
logging.warning("failed in clean-up routine")
logging.exception("failed in clean-up routine")
finally:
# Close Logging
logging.debug("close Logging")
@ -317,4 +345,4 @@ finally:
logging.shutdown()
fh.close()
ch.close()
exit(0)
exit(0)