From 572aad546bb8ee9ccd095a2098e1b292176c53da Mon Sep 17 00:00:00 2001
From: Andrew Cady <d@jerkface.net>
Date: Sat, 8 Apr 2017 16:16:51 -0400
Subject: re-implement polling using "devicer" library

---
 dexcom_reader/devicer.py       | 72 ++++++++++++++++++++++++++++++++++++++++++
 dexcom_reader/dexcom_dumper.py | 61 ++++++++++++++++++++++++++++++++++-
 2 files changed, 132 insertions(+), 1 deletion(-)
 create mode 100644 dexcom_reader/devicer.py

diff --git a/dexcom_reader/devicer.py b/dexcom_reader/devicer.py
new file mode 100644
index 0000000..79a0a72
--- /dev/null
+++ b/dexcom_reader/devicer.py
@@ -0,0 +1,72 @@
+import pyudev
+import threading
+
+class DevicePoller:
+   def __init__(self, dev):
+      self.device_added = threading.Event()
+      self.device_removed = threading.Event()
+      self.device = dev
+      self.wait_add = self.device_added.wait
+      self.wait_remove = self.device_removed.wait
+      self.have = self.device_added.is_set
+
+      if dev:
+         self.device_added.set()
+
+   def launch_observer(self, monitor, device_match):
+
+      if not monitor:
+         monitor = pyudev.Monitor.from_netlink(pyudev.Context())
+
+      def handle_event(action, device):
+         if action == 'add' and device_match(device):
+            self.device = device
+            self.device_removed.clear()
+            self.device_added.set()
+         elif action == 'remove' and device == self.device:
+            self.device = None
+            self.device_added.clear()
+            self.device_removed.set()
+
+      self.observer = pyudev.MonitorObserver(monitor, handle_event)
+      self.observer.start()
+
+   def stop_observer():
+      self.observer.stop()
+
+def simple_devicer(subsystem, predicate):
+   dev = None
+   context = pyudev.Context()
+   for try_dev in context.list_devices(subsystem=subsystem):
+      if predicate(try_dev):
+         dev = try_dev
+         break
+
+   monitor = pyudev.Monitor.from_netlink(context)
+   monitor.filter_by(subsystem)
+
+   devicer = DevicePoller(dev)
+   devicer.launch_observer(monitor, predicate)
+
+   return devicer
+
+if __name__ == '__main__':
+
+   dexcom_g5_product = '22a3/47/100'
+
+   def is_dexcom_g5(dev):
+      try: return dev.parent.get('PRODUCT') == dexcom_g5_product
+      except: return False
+
+   devicer = simple_devicer('tty', is_dexcom_g5)
+
+   while True:
+      print("waiting for device")
+      devicer.wait_add()
+      while devicer.have():
+         print("poll device {0}".format(devicer.device))
+         print("sleep(5)")
+         if devicer.wait_remove(5):
+            print("device removed")
+
+   devicer.stop_observer()
diff --git a/dexcom_reader/dexcom_dumper.py b/dexcom_reader/dexcom_dumper.py
index be5b0d8..e7db00e 100755
--- a/dexcom_reader/dexcom_dumper.py
+++ b/dexcom_reader/dexcom_dumper.py
@@ -4,6 +4,7 @@ import readdata
 import sys
 import json
 import traceback
+from devicer import simple_devicer
 # import requests # As this takes SEVEN SECONDS, it's delayed until needed
 from sys import stdout, stderr
 from datetime import timedelta, datetime
@@ -206,6 +207,64 @@ def poll_remote():
                 else:
                         sleep_verbose(10)
 
+def poll_remote_redux():
+        (n, r) = remote_update('EGV_DATA')
+        if n is None:
+                return 10
+        else:
+                now = dr.ReadSystemTime()
+                if n == 0:
+                        send_ping(now)
+                if r:
+                        for t in ['METER_DATA', 'INSERTION_TIME', 'USER_EVENT_DATA']:
+                        # TODO: track how long this takes & adjust sleep accordingly
+                                try:
+                                        remote_update(t)
+                                except:
+                                        traceback.print_exc()
+                        next_reading = (r.system_time - now + timedelta(minutes=5, seconds=2)).total_seconds()
+                        return max(10, next_reading)
+                else:
+                        return 10
+
+def poll_redux():
+        poll = poll_remote_redux
+
+        dexcom_g5_product = '22a3/47/100'
+
+        def is_dexcom_g5(dev):
+                try: return dev.parent.get('PRODUCT') == dexcom_g5_product
+                except: return False
+
+        devicer = simple_devicer('tty', is_dexcom_g5)
+
+        while True:
+            try:
+                print_verbose("Waiting for device.")
+                if not devicer.wait_add(600):
+                        continue
+                print_verbose("Device found.")
+
+                global dr
+                if dr:
+                        dr.Disconnect()
+                dr = readdata.DexcomG5(devicer.device.device_node)
+
+                print("Device opened.")
+                while devicer.have():
+                        print_verbose("Polling device.")
+                        try:
+                                sleeptime = poll()
+                        except:
+                                sleeptime = 10
+
+                        if devicer.wait_remove(sleeptime):
+                                print_verbose("Device unplugged.")
+                                dr.Disconnect()
+                                dr = None
+            except KeyboardInterrupt:
+                break
+
 def poll_stdout():
         (r, now) = read_recent_egv_data()
         connected(True)
@@ -343,5 +402,5 @@ def toJSON(o):
 {"dump_everything": dump_everything,
  "dump_cgm":        dump_cgm,
  "poll":            poll,
- "test":            test,
+ "test":            poll_redux,
 }[command]()
-- 
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