stateTest.py

#! /usr/bin/python

import sys, os, select, pg, time, traceback, datetime, socket



class StateTestError( Exception):
    value = None

    def __init__( self, value):
        self.value = value
        print >> sys.stderr, sys.exc_info()[0]
        print >> sys.stderr, '-'*60
        traceback.print_exc(file=sys.stderr)
        print >> sys.stderr, '-'*60

    def __str__( self):
        return repr( self.value)


class _Q:
    
    db = None   # our database connection

    def open( self):
        self.db = pg.connect( dbname="ls", host="contrabass.ls-cat.org", user="lsuser" )

    def close( self):
        self.db.close()

    def __init__( self):
        self.open()

    def reset( self):
        self.db.reset()

    def query( self, qs):
        if qs == '':
            return rtn
        if self.db.status == 0:
            self.reset()
        try:
            # ping the server
            qr = self.db.query(qs)
        except:
            print "Failed query: %s" % (qs)
            if self.db.status == 1:
                print >> sys.stderr, sys.exc_info()[0]
                print >> sys.stderr, '-'*60
                traceback.print_exc(file=sys.stderr)
                print >> sys.stderr, '-'*60
                return None
            # reset the connection, should
            # put in logic here to deal with transactions
            # as transactions are rolled back
            #
            self.db.reset()
            if self.db.status != 1:
                # Bad status even after a reset, bail
                raise StateTestError( 'Database Connection Lost')

            qr = self.db.query( qs)

        return qr

    def dictresult( self, qr):
        return qr.dictresult()

    def e( self, s):
        return pg.escape_string( s)

    def fileno( self):
        return self.db.fileno()

    def getnotify( self):
        return self.db.getnotify()


if __name__ == "__main__":
    _q = _Q()

    qs = 'select "State" & 1003 as rsp from cats.machinestate() where "Station"=2'

    lastRsp = None
    while 1:
        qr = _q.query( qs)
        rsp = qr.dictresult()[0]["rsp"]
        if lastRsp == None or rsp != lastRsp:
            print rsp
            lastRsp = rsp
        time.sleep(0.2)