--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/py/configwaiter.py	Sat Jul 06 18:29:45 2019 +0800
@@ -0,0 +1,62 @@
+import asyncio
+import aiohttp
+
+import utils
+from utils import L,D,EX,W,E
+import config
+
+class ConfigWaiter(object):
+    """ Waits for config updates from the server. http long polling """
+
+    def __init__(self, server):
+        self.server = server
+        self.epoch_tag = None
+        self.http_session = aiohttp.ClientSession()
+
+    @asyncio.coroutine
+    def run(self):
+        # wait until someting has been uploaded (the uploader itself waits 5 seconds)
+        yield from asyncio.sleep(10)
+        while True:
+            yield from self.do()
+
+            # avoid spinning too fast
+            yield from asyncio.sleep(1)
+
+    @asyncio.coroutine
+    def do(self):
+        try:
+            if self.epoch_tag:
+                headers = {'etag': self.epoch_tag}
+            else:
+                headers = None
+
+            r = yield from asyncio.wait_for(
+                self.http_session.get(config.SETTINGS_URL, headers=headers), 
+                300)
+            D("waiter status %d" % r.status)
+            if r.status == 200:
+                rawresp = yield from asyncio.wait_for(r.text(), 600)
+
+                resp = utils.json_load_round_float(rawresp)
+
+                self.epoch_tag = resp['epoch_tag']
+                D("waiter got epoch tag %s" % self.epoch_tag)
+                epoch = self.epoch_tag.split('-')[0]
+                if self.server.params.receive(resp['params'], epoch):
+                    self.server.reload_signal(True)
+            elif r.status == 304:
+                pass
+            else:
+                # longer timeout to avoid spinning
+                yield from asyncio.sleep(30)
+
+        except asyncio.TimeoutError:
+            D("configwaiter http timed out")
+            pass
+        except Exception as e:
+            EX("Error watching config: %s" % str(e))
+
+
+
+