ensure that storm httpapis tear down runtime tasks if the remote disconnects

synapse/lib/httpapi.py

@@ -269,6 +269,12 @@ async def _reqUserAllow(self, perm):
 
 class Handler(HandlerBase, t_web.RequestHandler):
 
+    def prepare(self):
+        self.task = asyncio.current_task()
+
+    def on_connection_close(self):
+        self.task.cancel()
+
     async def _reqValidOpts(self, opts):
 
         if opts is None:

synapse/tests/test_lib_httpapi.py

@@ -773,6 +773,42 @@ async def test_http_storm(self):
 
                     self.eq(0x01020304, node[0][1])
 
+                # Task cancellation during long running storm queries works as intended
+                body = {'query': '.created | sleep 10'}
+                task = None
+                async with sess.get(f'https://localhost:{port}/api/v1/storm', json=body) as resp:
+
+                    async for byts, x in resp.content.iter_chunks():
+
+                        if not byts:
+                            break
+
+                        mesg = json.loads(byts)
+                        if mesg[0] == 'node':
+                            task = core.boss.tasks.get(list(core.boss.tasks.keys())[0])
+                            break
+
+                self.nn(task)
+                self.true(await task.waitfini(6))
+                self.len(0, core.boss.tasks)
+
+                task = None
+                async with sess.get(f'https://localhost:{port}/api/v1/storm/nodes', json=body) as resp:
+
+                    async for byts, x in resp.content.iter_chunks():
+
+                        if not byts:
+                            break
+
+                        mesg = json.loads(byts)
+                        self.len(2, mesg) # Is if roughly shaped like a node?
+                        task = core.boss.tasks.get(list(core.boss.tasks.keys())[0])
+                        break
+
+                self.nn(task)
+                self.true(await task.waitfini(6))
+                self.len(0, core.boss.tasks)
+
                 # check reqvalidstorm with various queries
                 tvs = (
                     ('test:str=test', {}, 'ok'),