add a sticky value channel.. it pushes it's value, but the first

time it returns a stored value, if any...

solardash/__init__.py

@@ -38,6 +38,31 @@ logging.basicConfig(level=logging.DEBUG)
 from aiohttp import web
 from RainEagle.parse import LogDir as RELogDir, _cmaiter
 
+class StickyChannel(object):
+	def __init__(self):
+		self._queues = set()
+		self._lastvalue = None
+
+	async def post(self, value):
+		self._lastvalue = value
+
+		for i in self._queues:
+			await i.put(value)
+
+	async def __aiter__(self):
+		q = asyncio.Queue()
+
+		try:
+			self._queues.add(q)
+
+			if self._lastvalue is not None:
+				yield self._lastvalue
+
+			while True:
+				yield await q.get()
+		finally:
+			self._queues.remove(q)
+
 class SolarDataWS(object):
 	def __init__(self, reprefix):
 		self._raineagle = RELogDir(reprefix)
@@ -114,6 +139,103 @@ def async_test(f):
 
 	return wrapper
 
+class MiscTest(unittest.TestCase):
+	@async_test
+	async def test_stickychannel_waitfirst(self):
+		chan = StickyChannel()
+
+		loop = asyncio.get_event_loop()
+
+		order = []
+		dataval = 'data'
+		async def postmsg():
+			await asyncio.sleep(.02)
+			order.append('a')
+			await chan.post(dataval)
+			order.append('b')
+
+		postmsgtask = loop.create_task(postmsg())
+
+		async with _cmaiter(chan.__aiter__()) as chaniter:
+			order.append('c')
+			val = await chaniter.__anext__()
+			order.append('d')
+
+		self.assertEqual(val, dataval)
+
+		self.assertEqual(order, [ 'c', 'a', 'b', 'd' ])
+
+		await postmsgtask
+
+	@async_test
+	async def test_stickychannel_multiple(self):
+		chan = StickyChannel()
+
+		loop = asyncio.get_event_loop()
+
+		dataval = 'data'
+		dataval2 = 'data2'
+		async def postmsg():
+			await asyncio.sleep(.02)
+			await chan.post(dataval)
+			await asyncio.sleep(.01)
+			await chan.post(dataval2)
+
+		postmsgtask = loop.create_task(postmsg())
+
+		async with _cmaiter(chan.__aiter__()) as chaniter, \
+		    _cmaiter(chan.__aiter__()) as chaniter2:
+			val = await chaniter.__anext__()
+			val2 = await chaniter2.__anext__()
+
+			await asyncio.sleep(.01)
+
+			val3 = await chaniter.__anext__()
+			val4 = await chaniter2.__anext__()
+
+		async with _cmaiter(chan.__aiter__()) as chaniter3:
+			val5 = await chaniter3.__anext__()
+
+		self.assertEqual(val, dataval)
+		self.assertEqual(val2, dataval)
+		self.assertEqual(val3, dataval2)
+		self.assertEqual(val4, dataval2)
+		self.assertEqual(val5, dataval2)
+
+		await postmsgtask
+
+	@async_test
+	async def test_stickychannel_valuefirst(self):
+		chan = StickyChannel()
+
+		loop = asyncio.get_event_loop()
+
+		await chan.post(5)
+
+		order = []
+		dataval = 'data'
+		async def postmsg():
+			await asyncio.sleep(.02)
+			order.append('a')
+			await chan.post(dataval)
+			order.append('b')
+
+		postmsgtask = loop.create_task(postmsg())
+
+		async with _cmaiter(chan.__aiter__()) as chaniter:
+			order.append('c')
+			val = await chaniter.__anext__()
+			order.append('d')
+			val2 = await chaniter.__anext__()
+			order.append('e')
+
+		self.assertEqual(val, 5)
+		self.assertEqual(val2, dataval)
+
+		self.assertEqual(order, [ 'c', 'd', 'a', 'b', 'e' ])
+
+		await postmsgtask
+
 class Test(unittest.TestCase):
 	def setUp(self):
 		# setup temporary directory