class TrainObserver(object):
"""This class queries reiseauskunft.bahn.de at a fixed interval to for all
trains that travel on the travel connections that are stored in the
DatabaseBackend.
It determines if Trains are delayed or not and stores the result in the
DatabaseBackend.
"""
def __init__(self, databasePath):
"""Creates a new instance of TrainObserver.
@param databasePath Path to the DatabaseBackend that shall be used for
observation."""
self._db = DatabaseBackend(databasePath)
self._interval = 1 * 60# query every two minutes
self._lookAhead = 2 # query trains starting in two minutes
self._connections = self._db.connectionsAsList()
self._start()
def _start(self):
"""Starts the observation process."""
lastTrains = [] #remembers the trains that were retrieved last time
for i in range(len(self._connections)):
lastTrains.append([])
firstRun = True
while True:
print "Checking", len(self._connections), "connections"
concnt = 0
for c in self._connections:
tmp = localtime(time() + self._lookAhead * 60)
departure = strftime("%H:%M", tmp)
date = strftime("%d.%m.%Y", localtime())
trains = getTrains(c[0], c[1], date, departure)
tl = []
trainsToProcess = list(lastTrains[concnt])
for t in trains:
tl.append(t)
if not t.delay() is None:
try:
print "Detected delayed train: {0} -> {1} ({2}): {3}".\
format(t.start(), t.end(), t.product(),
"Start: {0}, delay: {1}".format(
t.departure(), t.delay()))
except:
pass
self.trainProcessed(t, trainsToProcess)
if not firstRun:
# are there trains left to be processed?
# if so, add them to the database, because they left the
# station
for t in trainsToProcess:
print "Adding train ", t.start(), t.end(), t.departure()
self._db.addTrain(t)
lastTrains[concnt] = tl
concnt += 1
firstRun = False
sleep(self._interval)
self._connections = self._db.connectionsAsList()
def trainProcessed(self, train, trains):
"""Checks if the train, that is processed is in the list of trains
that are expected to be processed. If so, it is removed from the list.
"""
for t in trains:
if t.departure() == train.departure() and\
t.start() == train.start() and\
t.end() == train.end():
trains.remove(t)
return
