Factor subscription broadcasting into a func

piker/data/_sampling.py

@@ -22,7 +22,7 @@ financial data flows.
 from __future__ import annotations
 from collections import Counter
 import time
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 import tractor
 import trio
@@ -90,6 +90,7 @@ async def increment_ohlc_buffer(
 
     total_s = 0  # total seconds counted
     lowest = min(sampler.ohlcv_shms.keys())
+    lowest_shm = sampler.ohlcv_shms[lowest][0]
     ad = lowest - 0.001
 
     with trio.CancelScope() as cs:
@@ -133,10 +134,22 @@ async def increment_ohlc_buffer(
                     # write to the buffer
                     shm.push(last)
 
+            await broadcast(delay_s, shm=lowest_shm)
+
+
+async def broadcast(
+    delay_s: int,
+    shm: Optional[ShmArray] = None,
+
+) -> None:
     # broadcast the buffer index step to any subscribers for
     # a given sample period.
     subs = sampler.subscribers.get(delay_s, ())
 
+    if shm is None:
+        lowest = min(sampler.ohlcv_shms.keys())
+        shm = sampler.ohlcv_shms[lowest][0]
+
     for stream in subs:
         try:
             await stream.send({'index': shm._last.value})