From 8108af95b1f698986415a941c4d9b1db2488da51 Mon Sep 17 00:00:00 2001
From: Andrew Cady <d@jerkface.net>
Date: Fri, 27 Jan 2017 14:09:19 +0000
Subject: dexcom_dumper: improved server update logic

---
 dexcom_reader/dexcom_dumper.py | 81 +++++++++++++++++++++++++++++++++++++-----
 1 file changed, 72 insertions(+), 9 deletions(-)

(limited to 'dexcom_reader')

diff --git a/dexcom_reader/dexcom_dumper.py b/dexcom_reader/dexcom_dumper.py
index f4cf7c5..95d1bee 100644
--- a/dexcom_reader/dexcom_dumper.py
+++ b/dexcom_reader/dexcom_dumper.py
@@ -158,17 +158,56 @@ def send_ping(now):
                 POST('/ping', toJSON(now))
 
 def print_cgm_bg(now, r):
-        if HOST:
-                remote_update('EGV_DATA')
-                send_ping(now)
-                return
-        elif JSON:
+        if JSON:
                 print toJSON(r)
         else:
                 print '%s: %s %s' % (format_times(now, r.system_time), r.glucose, r.trend_arrow)
         stdout.flush()
 
+def dexcom_reconnect():
+        global dr
+        dr = get_dexcom_reader()
+
 def poll():
+        if HOST:
+                poll_remote()
+        else:
+                poll_stdout()
+
+def poll_remote():
+        print_localtime('dexcom_dumper started')
+        connected = False
+        while True:
+                try:
+                        (n, r) = remote_update('EGV_DATA')
+                        if n is None:
+                                sleep_verbose(10)
+                                continue
+
+                        now = dr.ReadSystemTime()
+                        if n == 0:
+                                send_ping(now)
+                        if r:
+                                next_reading = (r.system_time - now + timedelta(minutes=5, seconds=2)).total_seconds()
+                                sleep_verbose(max(10, next_reading))
+                        else:
+                                sleep_verbose(10)
+                        connected = True
+                except ValueError as v:
+                        if connected:
+                                print_verbose('Dexcom is disconnected.')
+                                connected = False
+                        sleep(10)
+                        if (v.args[0] != 'Attempting to use a port that is not open'):
+                                dexcom_reconnect()
+                except KeyboardInterrupt:
+                        print_verbose('Exiting.')
+                        return
+                except:
+                        print_verbose(sys.exc_info())
+                        sleep(10)
+
+def poll_stdout():
         print_localtime('dexcom_dumper started')
         while True:
                 (r, now) = read_recent_egv_data()
@@ -177,7 +216,6 @@ def poll():
                         sleep_verbose(10)
                 elif r is None:
                         connected(True)
-                        send_ping(now)
                         sleep_verbose(10)
                 else:
                         connected(True)
@@ -188,11 +226,32 @@ def poll():
 
 def since(when, rectype):
         filt = lambda r: (r.system_time > when) if when else True
-        return reversed(list(takewhile(filt, dr.iter_records(rectype))))
+        return list(reversed(list(takewhile(filt, dr.iter_records(rectype)))))
+
+def since_and_first(when, rectype):
+        class closure:
+                fst = None
+        def filt(r):
+                closure.fst = closure.fst or r
+                return (r.system_time > when) if when else True
+        return (list(reversed(list(takewhile(filt, dr.iter_records(rectype))))), closure.fst)
 
 def parsetime(s):
         return datetime.strptime(s, "%Y-%m-%dT%H:%M:%SZ")
 
+# Update the remote site with any records of 'rectype' that are missing.
+# The server is queried to determine its last update.
+#
+# Returns (a,b) where:
+#
+# a = the number of records sent to the server (possibly zero), or None for a server error
+#
+# b = the latest record available on the Dexcom
+#
+# TODO: This has a race condition if you imagine multiple clients,
+# server restarts, etc.; it should send back the value it got in the
+# query to the server, so that the server can verify that the updates
+# are consecutive.
 def remote_update(rectype):
         requests = import_requests()
         url_path = '/' + rectype
@@ -204,10 +263,14 @@ def remote_update(rectype):
                 when = parsetime(resp.json()[0]['contents']['system_time'])
                 print_verbose("Latest record on server: %s" % when.isoformat())
 
-        rs = list(since(when, rectype))
+        (rs, r) = since_and_first(when, rectype)
         if len(rs):
                 print_verbose("Sending %d record%s... " % (len(rs), '' if len(rs) == 1 else 's'), newline=False)
-                print_verbose("done.  (Result: %s)" % POST(url_path, toJSON(rs)))
+                result = POST(url_path, toJSON(rs))
+                print_verbose("done.  (Result: %s)" % result)
+                return (len(rs) if result else None, r)
+        else:
+                return (0, r)
 
 def test():
         remote_update('EGV_DATA')
-- 
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