Flip `.feed` and `._sampling` over to new stuff

In `.feed` and `._sampling` move to using the new
`tractor.Context.open_stream(allow_overruns: bool)` (cough, A BREAKING
CHANGE).

Also set `Flume.mkt` during construction in `.feed.open_feed()`.

piker/data/_sampling.py

@@ -782,9 +782,6 @@ async def uniform_rate_send(
     https://gist.github.com/njsmith/7ea44ec07e901cb78ebe1dd8dd846cb9
 
     '''
-    # try not to error-out on overruns of the subscribed client
-    stream._ctx._backpressure = True
-
     # TODO: compute the approx overhead latency per cycle
     left_to_sleep = throttle_period = 1/rate - 0.000616
 

piker/data/feed.py

@@ -1116,7 +1116,7 @@ async def allocate_persistent_feed(
         # TODO: we have to use this for now since currently the
         # MktPair above doesn't render the correct output key it seems
         # when we provide the `MktInfo` here?..?
-        symbol=symbol,
+        mkt=symbol,
 
         first_quote=first_quote,
         _rt_shm_token=rt_shm.token,
@@ -1206,10 +1206,6 @@ async def open_feed_bus(
     symbol.
 
     '''
-    # ensure that a quote feed stream which is pushing too fast doesn't
-    # cause and overrun in the client.
-    ctx._backpressure = True
-
     if loglevel is None:
         loglevel = tractor.current_actor().loglevel
 
@@ -1285,8 +1281,7 @@ async def open_feed_bus(
     # sync feed subscribers with flume handles
     await ctx.started(
         {fqsn: flume.to_msg()
-         for fqsn, flume in flumes.items()
-        }
+         for fqsn, flume in flumes.items()}
     )
 
     if not start_stream:
@@ -1295,7 +1290,12 @@ async def open_feed_bus(
 
     # real-time stream loop
     async with (
-        ctx.open_stream() as stream,
+        ctx.open_stream(
+            # NOTE we allow this since it's common to have the live
+            # quote feed actor's sampling task push faster then the
+            # the local UI-graphics code during startup.
+            allow_overruns=True,
+        ) as stream,
     ):
 
         local_subs: dict[str, set[tuple]] = {}
@@ -1323,7 +1323,6 @@ async def open_feed_bus(
                 # a max ``tick_throttle`` instantaneous rate.
                 send, recv = trio.open_memory_channel(2**10)
 
-                ctx._backpressure = False
                 cs = await bus.start_task(
                     uniform_rate_send,
                     tick_throttle,
@@ -1455,14 +1454,6 @@ class Feed(Struct):
 
     _max_sample_rate: int = 1
 
-    # @property
-    # def portal(self) -> tractor.Portal:
-    #     return self._portal
-
-    # @property
-    # def name(self) -> str:
-    #     return self.mod.name
-
     async def pause(self) -> None:
         for stream in set(self.streams.values()):
             await stream.send('pause')
@@ -1537,7 +1528,7 @@ async def maybe_open_feed(
             'tick_throttle': kwargs.get('tick_throttle'),
 
             # XXX: super critical to have bool defaults here XD
-            'backpressure': kwargs.get('backpressure', True),
+            'allow_overruns': kwargs.get('allow_overruns', True),
             'start_stream': kwargs.get('start_stream', True),
         },
         key=fqsn,
@@ -1569,7 +1560,7 @@ async def open_feed(
     fqsns: list[str],
 
     loglevel: str | None = None,
-    backpressure: bool = True,
+    allow_overruns: bool = True,
     start_stream: bool = True,
     tick_throttle: float | None = None,  # Hz
 
@@ -1659,9 +1650,6 @@ async def open_feed(
                 (brokermod, bfqsns),
             ) in zip(ctxs, providers.items()):
 
-                # NOTE: do it asap to avoid overruns during multi-feed setup?
-                ctx._backpressure = backpressure
-
                 for fqsn, flume_msg in flumes_msg_dict.items():
                     flume = Flume.from_msg(flume_msg)
                     assert flume.symbol.fqsn == fqsn
@@ -1683,11 +1671,11 @@ async def open_feed(
 
                 stream_ctxs.append(
                     ctx.open_stream(
-                        # XXX: be explicit about stream backpressure
+                        # XXX: be explicit about stream overruns
                         # since we should **never** overrun on feeds
                         # being too fast, which will pretty much
                         # always happen with HFT XD
-                        backpressure=backpressure,
+                        allow_overruns=allow_overruns,
                     )
                 )