Start of asynchronous support - reading database & vending machine simultaneously

[zanchey/dispense2.git] / sql-edition / servers / VendServer.py

diff --git a/sql-edition/servers/VendServer.py b/sql-edition/servers/VendServer.py
index 3f806bc..c3f04bc 100755 (executable)
--- a/sql-edition/servers/VendServer.py
+++ b/sql-edition/servers/VendServer.py
@@ -1,18 +1,54 @@
 #!/usr/bin/python
 
 import sys, os, string, socket, time, re
-from popen2 import popen2
-from pyPgSQL import PgSQL
+import pg
 from LATClient import LATClient
 from VendingMachine import VendingMachine
 
+class DispenseDatabase:
+       def __init__(self, vending_machine):
+               self.vending_machine = vending_machine
+               self.db = pg.DB(dbname = 'dispense', host = 'dispense.ucc.gu.uwa.edu.au', user = 'vendserver', passwd = 'revresdnev')
+               self.db.query('LISTEN vend_requests')
+
+       def process_requests(self):
+               print 'processing'
+               query = 'SELECT request_id, request_slot FROM vend_requests WHERE request_handled = false'
+               try:
+                       outstanding = self.db.query(query).getresult()
+               except (pg.error,), db_err:
+                       sys.stderr.write('Failed to query database: %s\n'%(db_err.strip()))
+                       return
+               for (id, slot) in outstanding:
+                       (worked, code, string) = self.vending_machine.vend(slot)
+                       print (worked, code, string)
+                       if worked:
+                               query = 'SELECT vend_success(%s)'%id
+                               self.db.query(query).getresult()
+                       else:
+                               query = 'SELECT vend_failed(%s)'%id
+                               self.db.query(query).getresult()
+
+       def handle_events(self):
+               notifier = self.db.getnotify()
+               while notifier is not None:
+                       self.process_requests()
+                       notify = self.db.getnotify()
+
 if __name__ == '__main__':
        # Open vending machine via LAT
        latclient = LATClient(service = 'VEND', password = 'dmscptd')
        (rfh, wfh) = latclient.get_fh()
        v = VendingMachine(rfh, wfh)
        print 'PING is', v.ping()
-       print 'BEEP is', v.beep()
-       print 'VEND 11 is', v.vend('11')
-       print 'SILENCE is', v.silence()
-       print 'DISPLAY is', v.display('GOOD NIGHT')
+       #print 'BEEP is', v.beep()
+       #print 'VEND 11 is', v.vend('11')
+       #print 'SILENCE is', v.silence()
+       #print 'DISPLAY is', v.display('WELCOME')
+       print 'S is', v.get_switches()
+
+       db = DispenseDatabase(v)
+       db.process_requests()
+       while True:
+               v.wait_for_events(1)
+               db.handle_events()