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 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 dexcom_reader/devicer.py

(limited to '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()
-- 
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