#!/usr/bin/python3 -u
# The -u option above turns off block buffering of python output. This
# assures that each error message gets individually printed to the log file.
#
# Module: radmonAgent.py
#
# Description: This module acts as an agent between the radiation monitoring
# device and Internet web services. The agent periodically sends an http
# request to the radiation monitoring device and processes the response from
# the device and performs a number of operations:
# - conversion of data items
# - update a round robin (rrdtool) database with the radiation data
# - periodically generate graphic charts for display in html documents
# - write the processed radmon data to a JSON file for use by html
# documents
#
# Copyright 2015 Jeff Owrey
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see http://www.gnu.org/license.
#
# Revision History
# * v20 released 15 Sep 2015 by J L Owrey; first release
# * v21 released 27 Nov 2017 by J L Owrey; bug fixes; updates
# * v22 released 03 Mar 2018 by J L Owrey; improved code readability;
# improved radmon device offline status handling
# * v23 released 16 Nov 2018 by J L Owrey: improved fault handling
# and data conversion
# * v24 released 14 Jun 2021 by J L Owrey; minor revisions
# * v25 released 9 Jul 2021 by J L Owrey; improved handling of
# monitor status function
#
#2345678901234567890123456789012345678901234567890123456789012345678901234567890
import os
import sys
import signal
import multiprocessing
import time
import calendar
import json
from urllib.request import urlopen
import rrdbase
### ENVIRONMENT ###
_USER = os.environ['USER']
_SERVER_MODE = "primary"
_USE_RADMON_TIMESTAMP = True
### DEFAULT RADIATION MONITOR URL ###
_DEFAULT_RADIATION_MONITOR_URL = \
"{your radiation monitor URL}"
### FILE AND FOLDER LOCATIONS ###
# folder for containing dynamic data objects
_DOCROOT_PATH = "/home/%s/public_html/radmon/" % _USER
# folder for charts and output data file
_CHARTS_DIRECTORY = _DOCROOT_PATH + "dynamic/"
# location of data output file
_OUTPUT_DATA_FILE = _DOCROOT_PATH + "dynamic/radmonData.js"
# database that stores radmon data
_RRD_FILE = "/home/%s/database/radmonData.rrd" % _USER
### GLOBAL CONSTANTS ###
# maximum number of failed data requests allowed
_MAX_FAILED_DATA_REQUESTS = 2
# maximum number of http request retries allowed
_MAX_HTTP_RETRIES = 5
# delay time between http request retries
_HTTP_RETRY_DELAY = 1.119
# interval in seconds between data requests
_DEFAULT_DATA_REQUEST_INTERVAL = 5
# number seconds to wait for a response to HTTP request
_HTTP_REQUEST_TIMEOUT = 3
# interval in seconds between database updates
_DATABASE_UPDATE_INTERVAL = 30
# interval in seconds between chart updates
_CHART_UPDATE_INTERVAL = 300
# standard chart width in pixels
_CHART_WIDTH = 600
# standard chart height in pixels
_CHART_HEIGHT = 150
### GLOBAL VARIABLES ###
# turn on or off of verbose debugging information
verboseMode = False
debugMode = False
reportUpdateFails = False
# The following two items are used for detecting system faults
# and radiation monitor online or offline status.
# count of failed attempts to get data from radiation monitor
failedUpdateCount = 0
httpRetries = 0
radmonOnline = False
# status of reset command to radiation monitor
remoteDeviceReset = False
# ip address of radiation monitor
radiationMonitorUrl = _DEFAULT_RADIATION_MONITOR_URL
# web update frequency
dataRequestInterval = _DEFAULT_DATA_REQUEST_INTERVAL
# rrdtool database interface handler
rrdb = None
### PRIVATE METHODS ###
def getTimeStamp():
"""
Set the error message time stamp to the local system time.
Parameters: none
Returns: string containing the time stamp
"""
return time.strftime( "%m/%d/%Y %T", time.localtime() )
## end def
def setStatusToOffline():
"""Set the detected status of the radiation monitor to
"offline" and inform downstream clients by removing input
and output data files.
Parameters: none
Returns: nothing
"""
global radmonOnline
# Inform downstream clients by removing output data file.
if os.path.exists(_OUTPUT_DATA_FILE):
os.remove(_OUTPUT_DATA_FILE)
# If the radiation monitor was previously online, then send
# a message that we are now offline.
if radmonOnline:
print('%s radiation monitor offline' % getTimeStamp())
radmonOnline = False
## end def
def terminateAgentProcess(signal, frame):
"""Send a message to log when the agent process gets killed
by the operating system. Inform downstream clients
by removing input and output data files.
Parameters:
signal, frame - dummy parameters
Returns: nothing
"""
# Inform downstream clients by removing output data file.
if os.path.exists(_OUTPUT_DATA_FILE):
os.remove(_OUTPUT_DATA_FILE)
print('%s terminating radmon agent process' % \
(getTimeStamp()))
sys.exit(0)
## end def
### PUBLIC METHODS ###
def getRadiationData(dData):
"""Send http request to radiation monitoring device. The
response from the device contains the radiation data as
unformatted ascii text.
Parameters: none
Returns: a string containing the radiation data if successful,
or None if not successful
"""
global httpRetries
sUrl = radiationMonitorUrl
if remoteDeviceReset:
sUrl += "/reset" # reboot the radiation monitor
else:
sUrl += "/rdata" # request data from the monitor
try:
currentTime = time.time()
response = urlopen(sUrl, timeout=_HTTP_REQUEST_TIMEOUT)
requestTime = time.time() - currentTime
content = response.read().decode('utf-8')
content = content.replace('\n', '')
content = content.replace('\r', '')
if content == "":
raise Exception("empty response")
except Exception as exError:
# If no response is received from the device, then assume that
# the device is down or unavailable over the network. In
# that case return None to the calling function.
httpRetries += 1
if reportUpdateFails:
print("%s " % getTimeStamp(), end='')
if reportUpdateFails or verboseMode:
print("http request failed (%d): %s" % \
(httpRetries, exError))
if httpRetries > _MAX_HTTP_RETRIES:
httpRetries = 0
return False
else:
time.sleep(_HTTP_RETRY_DELAY)
return getRadiationData(dData)
## end try
if debugMode:
print(content)
if verboseMode:
print("http request successful: %.4f sec" % requestTime)
httpRetries = 0
dData['content'] = content
return True
## end def
def parseDataString(dData):
"""Parse the data string returned by the radiation monitor
into its component parts.
Parameters:
dData - a dictionary object to contain the parsed data items
Returns: True if successful, False otherwise
"""
# Example radiation monitor data string
# $,UTC=17:09:33 6/22/2021,CPS=0,CPM=26,uSv/hr=0.14,Mode=SLOW,#
try:
sData = dData.pop('content')
lData = sData[2:-2].split(',')
except Exception as exError:
print("%s parseDataString: %s" % (getTimeStamp(), exError))
return False
# Verfy the expected number of data items have been received.
if len(lData) != 5:
print("%s parse failed: corrupted data string" % getTimeStamp())
return False;
# Load the parsed data into a dictionary for easy access.
for item in lData:
if "=" in item:
dData[item.split('=')[0]] = item.split('=')[1]
# Add status to dictionary object
dData['status'] = 'online'
dData['serverMode'] = _SERVER_MODE
return True
## end def
def convertData(dData):
"""Convert individual radiation data items as necessary.
Parameters:
dData - a dictionary object containing the radiation data
Returns: True if successful, False otherwise
"""
try:
if _USE_RADMON_TIMESTAMP:
# Convert the UTC timestamp provided by the radiation monitoring
# device to epoch local time in seconds.
ts_utc = time.strptime(dData['UTC'], "%H:%M:%S %m/%d/%Y")
epoch_local_sec = calendar.timegm(ts_utc)
else:
# Use a timestamp generated by the requesting server (this)
# instead of the timestamp provided by the radiation monitoring
# device. Using the server generated timestamp prevents errors
# that occur when the radiation monitoring device fails to
# synchronize with a valid NTP time server.
epoch_local_sec = time.time()
dData['date'] = \
time.strftime("%m/%d/%Y %T", time.localtime(epoch_local_sec))
dData['mode'] = dData.pop('Mode').lower()
dData['uSvPerHr'] = '%.2f' % float(dData['uSv/hr'])
# The rrdtool database stores whole units, so convert uSv to Sv.
dData['SvPerHr'] = float(dData.pop('uSv/hr')) * 1.0E-06
except Exception as exError:
print("%s data conversion failed: %s" % (getTimeStamp(), exError))
return False
return True
## end def
def writeOutputFile(dData):
"""Write radiation data items to the output data file, formatted as
a JSON file. This file may then be accessed and used by
by downstream clients, for instance, in HTML documents.
Parameters:
dData - a dictionary object containing the data to be written
to the output data file
Returns: True if successful, False otherwise
"""
# Format the radmon data as string using java script object notation.
jsData = json.loads("{}")
try:
for key in dData:
jsData.update({key:dData[key]})
sData = "[%s]" % json.dumps(jsData)
except Exception as exError:
print("%s writeOutputFile: %s" % (getTimeStamp(), exError))
return False
if debugMode:
print(sData)
# Write the string to the output data file for use by html documents.
try:
fc = open(_OUTPUT_DATA_FILE, "w")
fc.write(sData)
fc.close()
except Exception as exError:
print("%s writeOutputFile: %s" % (getTimeStamp(), exError))
return False
return True
## end def
def setRadmonStatus(updateSuccess):
"""Detect if radiation monitor is offline or not available on
the network. After a set number of attempts to get data
from the monitor set a flag that the radmon is offline.
Parameters:
updateSuccess - a boolean that is True if data request
successful, False otherwise
Returns: nothing
"""
global failedUpdateCount, radmonOnline
if updateSuccess:
failedUpdateCount = 0
# Set status and send a message to the log if the device
# previously offline and is now online.
if not radmonOnline:
print('%s radiation monitor online' % getTimeStamp())
radmonOnline = True
return
else:
# The last attempt failed, so update the failed attempts
# count.
failedUpdateCount += 1
if failedUpdateCount == _MAX_FAILED_DATA_REQUESTS:
# Max number of failed data requests, so set
# device status to offline.
setStatusToOffline()
## end def
### GRAPH FUNCTIONS ###
def generateGraphs():
"""Generate graphs for display in html documents.
Parameters: none
Returns: nothing
"""
autoScale = False
# past 24 hours
rrdb.createAutoGraph('24hr_cpm', 'CPM', 'counts\ per\ minute',
'CPM\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2, autoScale)
rrdb.createAutoGraph('24hr_svperhr', 'SvperHr', 'Sv\ per\ hour',
'Sv/Hr\ -\ Last\ 24\ Hours', 'end-1day', 0, 0, 2, autoScale)
# past 4 weeks
rrdb.createAutoGraph('4wk_cpm', 'CPM', 'counts\ per\ minute',
'CPM\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2, autoScale)
rrdb.createAutoGraph('4wk_svperhr', 'SvperHr', 'Sv\ per\ hour',
'Sv/Hr\ -\ Last\ 4\ Weeks', 'end-4weeks', 0, 0, 2, autoScale)
# past year
rrdb.createAutoGraph('12m_cpm', 'CPM', 'counts\ per\ minute',
'CPM\ -\ Past\ Year', 'end-12months', 0, 0, 2, autoScale)
rrdb.createAutoGraph('12m_svperhr', 'SvperHr', 'Sv\ per\ hour',
'Sv/Hr\ -\ Past\ Year', 'end-12months', 0, 0, 2, autoScale)
## end def
def getCLarguments():
"""Get command line arguments. There are four possible arguments
-d turns on debug mode
-v turns on verbose mode
-t sets the radiation device query interval
-u sets the url of the radiation monitoring device
Returns: nothing
"""
global verboseMode, debugMode, dataRequestInterval, \
radiationMonitorUrl, reportUpdateFails
index = 1
while index < len(sys.argv):
if sys.argv[index] == '-v':
verboseMode = True
elif sys.argv[index] == '-d':
verboseMode = True
debugMode = True
elif sys.argv[index] == '-r':
reportUpdateFails = True
# Update period and url options
elif sys.argv[index] == '-p':
try:
dataRequestInterval = abs(float(sys.argv[index + 1]))
except:
print("invalid polling period")
exit(-1)
index += 1
elif sys.argv[index] == '-u':
radiationMonitorUrl = sys.argv[index + 1]
if radiationMonitorUrl.find('http://') < 0:
radiationMonitorUrl = 'http://' + radiationMonitorUrl
index += 1
else:
cmd_name = sys.argv[0].split('/')
print("Usage: %s [-d] [-p seconds] [-u url}" % cmd_name[-1])
exit(-1)
index += 1
## end def
def setup():
"""Handles timing of events and acts as executive routine managing
all other functions.
Parameters: none
Returns: nothing
"""
global rrdb
## Get command line arguments.
getCLarguments()
print('====================================================')
print('%s starting up radmon agent process' % \
(getTimeStamp()))
## Exit with error if rrdtool database does not exist.
if not os.path.exists(_RRD_FILE):
print('rrdtool database does not exist\n' \
'use createRadmonRrd script to ' \
'create rrdtool database\n')
exit(1)
signal.signal(signal.SIGTERM, terminateAgentProcess)
signal.signal(signal.SIGINT, terminateAgentProcess)
# Define object for calling rrdtool database functions.
rrdb = rrdbase.rrdbase( _RRD_FILE, _CHARTS_DIRECTORY, _CHART_WIDTH, \
_CHART_HEIGHT, verboseMode, debugMode )
## end def
def loop():
# last time output JSON file updated
lastDataRequestTime = -1
# last time charts generated
lastChartUpdateTime = - 1
# last time the rrdtool database updated
lastDatabaseUpdateTime = -1
while True:
currentTime = time.time() # get current time in seconds
# Every data update interval request data from the radiation
# monitor and process the received data.
if currentTime - lastDataRequestTime > dataRequestInterval:
lastDataRequestTime = currentTime
dData = {}
# Get the data string from the device.
result = getRadiationData(dData)
# If successful parse the data.
if result:
result = parseDataString(dData)
# If parsing successful, convert the data.
if result:
result = convertData(dData)
# If conversion successful, write data to data files.
if result:
writeOutputFile(dData)
# At the rrdtool database update interval, update the database.
if result and (currentTime - lastDatabaseUpdateTime > \
_DATABASE_UPDATE_INTERVAL):
lastDatabaseUpdateTime = currentTime
## Update the round robin database with the parsed data.
result = rrdb.updateDatabase(dData['date'], \
dData['CPM'], dData['SvPerHr'])
# Set the radmon status to online or offline depending on the
# success or failure of the above operations.
setRadmonStatus(result)
# At the chart generation interval, generate charts.
if currentTime - lastChartUpdateTime > _CHART_UPDATE_INTERVAL:
lastChartUpdateTime = currentTime
p = multiprocessing.Process(target=generateGraphs, args=())
p.start()
# Relinquish processing back to the operating system until
# the next update interval.
elapsedTime = time.time() - currentTime
if verboseMode:
if result:
print("update successful: %6f sec\n"
% elapsedTime)
else:
print("update failed: %6f sec\n"
% elapsedTime)
remainingTime = dataRequestInterval - elapsedTime
if remainingTime > 0.0:
time.sleep(remainingTime)
## end while
## end def
if __name__ == '__main__':
setup()
loop()