From 3d4898c4d5144770624188fcad3f90974cb3716c Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <jgbt@protonmail.com>
Date: Tue, 10 Aug 2021 16:50:40 -0400
Subject: [PATCH] Use `maybe_open_feed()` in ems and fsp daemons

---
 piker/clearing/_client.py |  4 ++--
 piker/clearing/_ems.py    | 17 ++++++-----------
 piker/data/feed.py        | 10 +++++-----
 piker/fsp/__init__.py     | 23 +++++++++++++++--------
 4 files changed, 28 insertions(+), 26 deletions(-)

diff --git a/piker/clearing/_client.py b/piker/clearing/_client.py
index 97869bb9..513dded8 100644
--- a/piker/clearing/_client.py
+++ b/piker/clearing/_client.py
@@ -38,7 +38,7 @@ log = get_logger(__name__)
 
 @dataclass
 class OrderBook:
-    """Buy-side (client-side ?) order book ctl and tracking.
+    '''EMS-client-side order book ctl and tracking.
 
     A style similar to "model-view" is used here where this api is
     provided as a supervised control for an EMS actor which does all the
@@ -48,7 +48,7 @@ class OrderBook:
     Currently, this is mostly for keeping local state to match the EMS
     and use received events to trigger graphics updates.
 
-    """
+    '''
     # mem channels used to relay order requests to the EMS daemon
     _to_ems: trio.abc.SendChannel
     _from_order_book: trio.abc.ReceiveChannel
diff --git a/piker/clearing/_ems.py b/piker/clearing/_ems.py
index 06536859..91197d60 100644
--- a/piker/clearing/_ems.py
+++ b/piker/clearing/_ems.py
@@ -32,9 +32,8 @@ import tractor
 
 from ..log import get_logger
 from ..data._normalize import iterticks
-from ..data.feed import Feed, open_feed
+from ..data.feed import Feed, maybe_open_feed
 from .._daemon import maybe_spawn_brokerd
-from .._cacheables import maybe_open_ctx
 from . import _paper_engine as paper
 from ._messages import (
     Status, Order,
@@ -959,15 +958,11 @@ async def _emsd_main(
 
     # spawn one task per broker feed
     async with (
-        maybe_open_ctx(
-            key=(broker, symbol),
-            mngr=open_feed(
-                broker,
-                [symbol],
-                loglevel=loglevel,
-            ),
+        maybe_open_feed(
+            broker,
+            [symbol],
             loglevel=loglevel,
-        ) as feed,
+        ) as (feed, stream),
     ):
 
         # XXX: this should be initial price quote from target provider
@@ -1011,7 +1006,7 @@ async def _emsd_main(
 
                     brokerd_stream,
                     ems_client_order_stream,
-                    feed.stream,
+                    stream,
                     broker,
                     symbol,
                     book
diff --git a/piker/data/feed.py b/piker/data/feed.py
index c56c0720..07df13a1 100644
--- a/piker/data/feed.py
+++ b/piker/data/feed.py
@@ -441,7 +441,7 @@ async def open_feed(
     tick_throttle: Optional[float] = None,  # Hz
     shielded_stream: bool = False,
 
-) -> ReceiveChannel[dict[str, Any]]:
+) -> Feed:
     '''
     Open a "data feed" which provides streamed real-time quotes.
 
@@ -522,7 +522,7 @@ async def open_feed(
         feed._max_sample_rate = max(ohlc_sample_rates)
 
         try:
-            yield feed, bstream
+            yield feed
         finally:
             # drop the infinite stream connection
             await ctx.cancel()
@@ -538,7 +538,7 @@ async def maybe_open_feed(
     tick_throttle: Optional[float] = None,  # Hz
     shielded_stream: bool = False,
 
-) -> ReceiveChannel[dict[str, Any]]:
+) -> (Feed, ReceiveChannel[dict[str, Any]]):
     '''Maybe open a data to a ``brokerd`` daemon only if there is no
     local one for the broker-symbol pair, if one is cached use it wrapped
     in a tractor broadcast receiver.
@@ -553,12 +553,12 @@ async def maybe_open_feed(
             [sym],
             loglevel=loglevel,
         ),
-    ) as (cache_hit, (feed, stream)):
+    ) as (cache_hit, feed):
 
         if cache_hit:
             # add a new broadcast subscription for the quote stream
             # if this feed is likely already in use
-            async with stream.subscribe() as bstream:
+            async with feed.stream.subscribe() as bstream:
                 yield feed, bstream
         else:
             yield feed, stream
diff --git a/piker/fsp/__init__.py b/piker/fsp/__init__.py
index 312a0cef..3b5c359a 100644
--- a/piker/fsp/__init__.py
+++ b/piker/fsp/__init__.py
@@ -69,6 +69,7 @@ async def fsp_compute(
     ctx: tractor.Context,
     symbol: str,
     feed: Feed,
+    stream: trio.abc.ReceiveChannel,
 
     src: ShmArray,
     dst: ShmArray,
@@ -93,14 +94,14 @@ async def fsp_compute(
         yield {}
 
         # task cancellation won't kill the channel
-        with stream.shield():
-            async for quotes in stream:
-                for symbol, quotes in quotes.items():
-                    if symbol == sym:
-                        yield quotes
+        # since we shielded at the `open_feed()` call
+        async for quotes in stream:
+            for symbol, quotes in quotes.items():
+                if symbol == sym:
+                    yield quotes
 
     out_stream = func(
-        filter_by_sym(symbol, feed.stream),
+        filter_by_sym(symbol, stream),
         feed.shm,
     )
 
@@ -164,7 +165,8 @@ async def cascade(
     dst_shm_token: Tuple[str, np.dtype],
     symbol: str,
     fsp_func_name: str,
-) -> AsyncIterator[dict]:
+
+) -> None:
     """Chain streaming signal processors and deliver output to
     destination mem buf.
 
@@ -175,7 +177,11 @@ async def cascade(
     func: Callable = _fsps[fsp_func_name]
 
     # open a data feed stream with requested broker
-    async with data.open_feed(brokername, [symbol]) as feed:
+    async with data.feed.maybe_open_feed(
+        brokername,
+        [symbol],
+        shielded_stream=True,
+    ) as (feed, stream):
 
         assert src.token == feed.shm.token
 
@@ -186,6 +192,7 @@ async def cascade(
             ctx=ctx,
             symbol=symbol,
             feed=feed,
+            stream=stream,
 
             src=src,
             dst=dst,