Flow API - update gateway (#357)

* Altered API to incorporate Flow IDs, refactored for dynamic start/stop of flows
* Gateway: Split endpoint / dispatcher for maintainability

trustgraph-base/trustgraph/base/publisher.py

@@ -15,17 +15,22 @@ class Publisher:
         self.q = asyncio.Queue(maxsize=max_size)
         self.chunking_enabled = chunking_enabled
         self.running = True
+        self.task = None
 
     async def start(self):
         self.task = asyncio.create_task(self.run())
 
     async def stop(self):
         self.running = False
-        await self.task
+
+        if self.task:
+            await self.task
 
     async def join(self):
         await self.stop()
-        await self.task
+
+        if self.task:
+            await self.task
 
     async def run(self):
 

trustgraph-base/trustgraph/base/subscriber.py

@@ -19,6 +19,7 @@ class Subscriber:
         self.lock = asyncio.Lock()
         self.running = True
         self.metrics = metrics
+        self.task = None
 
     def __del__(self):
         self.running = False
@@ -28,11 +29,15 @@ class Subscriber:
 
     async def stop(self):
         self.running = False
-        await self.task
+
+        if self.task:
+            await self.task
 
     async def join(self):
         await self.stop()
-        await self.task
+
+        if self.task:
+            await self.task
 
     async def run(self):
 
@@ -45,6 +50,8 @@ class Subscriber:
 
             try:
 
+                # FIXME: Create consumer in start  method so we know
+                # it is definitely running when start completes
                 consumer = self.client.subscribe(
                     topic = self.topic,
                     subscription_name = self.subscription,