Improve poll script

poll.py

@@ -7,6 +7,7 @@ import grequests
 import json
 from argparse import ArgumentParser
 
+# exchanges as (url, id, response_indices_last, currency)
 exchanges = [
     ('https://btc-e.com/api/3/ticker/btc_usd',
         'btce', ('btc_usd', 'last'), 'USD'),
@@ -42,6 +43,8 @@ if __name__ == '__main__':
                         '(default dev/shm/tothemoon)')
     parser.add_argument('-i', '--interval', metavar='SECONDS=2', type=float,
                         default=2, help='exchange poll interval')
+    parser.add_argument('-t', '--timeout', metavar='SECONDS=7', type=float,
+                        default=5, help='timeout for polling')
     parser.add_argument('-l', '--list', action='store_true', default=False,
                         help='list api info')
     args = parser.parse_args()
@@ -79,8 +82,7 @@ if __name__ == '__main__':
             print >>sys.stderr, e.strerror
             sys.exit(1)
 
-    # keep updating URLs from priority queue, adding them back to the queue
-    # scheduled after their current interval
+    # poll APIs in endless loop
     try:
         last_update = 0
 
@@ -89,35 +91,39 @@ if __name__ == '__main__':
             if diff < args.interval:
                 time.sleep(args.interval - diff)
 
-            requests = (grequests.get(ex[0], timeout=args.interval * 1.5)
+            requests = (grequests.get(ex[0], timeout=args.timeout)
                         for ex in exchanges)
             responses = grequests.map(requests, exception_handler=handle_error)
 
             for (url, exid, indices, currency), res in zip(exchanges, responses):
-                status = {'last': None, 'currency': currency, 'updated': 0}
-
                 if res is None:
-                    print >>sys.stderr, exid, 'unknown error'
+                    print >>sys.stderr, 'Unknown error at %s' % exid
                 elif res.status_code != 200:
-                    print >>sys.stderr, 'server error %d at %s' % (res.status_code, exid)
+                    print >>sys.stderr, 'Server error %d at %s' % \
+                            (res.status_code, exid)
                 else:
                     try:
                         last = res.json()
 
                         for i in indices:
                             last = last[i]
-                        last = float(last)
 
-                        status['updated'] = time.time()
-                        status['last'] = last
-                    except ValueError as e:
-                        print >>sys.stderr, 'invalid response from %s:' % exid, e.message
-                    except KeyError as e:
-                        print >>sys.stderr, 'unexpected response content from %s:' % exid, res.text
+                        status = {
+                            'last': float(last),
+                            'currency': currency,
+                            'updated': time.time()
+                        }
 
                         with open(root + '/' + exid, 'w') as f:
                             json.dump(status, f)
 
+                    except ValueError as e:
+                        print >>sys.stderr, 'Invalid response from %s:' % \
+                                exid, e.message
+                    except KeyError as e:
+                        print >>sys.stderr, 'Unexpected response ' \
+                                'content from %s:' % exid, res.text
+
             last_update = time.time()
     except KeyboardInterrupt:
         pass