Make `Flume.index_stream()` defer to new sampling api

piker/data/flows.py

@@ -21,6 +21,7 @@ real-time data processing data-structures.
 "Streams, flumes, cascades and flows.."
 
 """
+from __future__ import annotations
 from contextlib import asynccontextmanager as acm
 from functools import partial
 from typing import (
@@ -45,7 +46,7 @@ from ._sharedmem import (
     _Token,
 )
 from ._sampling import (
-    iter_ohlc_periods,
+    open_sample_stream,
 )
 
 if TYPE_CHECKING:
@@ -149,7 +150,7 @@ class Flume(Struct):
     @acm
     async def index_stream(
         self,
-        delay_s: int = 1,
+        delay_s: float = 1,
 
     ) -> AsyncIterator[int]:
 
@@ -163,21 +164,8 @@ class Flume(Struct):
         # XXX: this should be singleton on a host,
         # a lone broker-daemon per provider should be
         # created for all practical purposes
-        async with maybe_open_context(
-            acm_func=partial(
-                portal.open_context,
-                iter_ohlc_periods,
-            ),
-            kwargs={'delay_s': delay_s},
-        ) as (cache_hit, (ctx, first)):
-            async with ctx.open_stream() as istream:
-                if cache_hit:
-                    # add a new broadcast subscription for the quote stream
-                    # if this feed is likely already in use
-                    async with istream.subscribe() as bistream:
-                        yield bistream
-                else:
-                    yield istream
+        async with open_sample_stream(float(delay_s)) as stream:
+            yield stream
 
     def get_ds_info(
         self,