Define a flow registry on `FspAdmin`, use it to update fsp engine clusters

piker/ui/_fsp.py

@@ -37,6 +37,7 @@ from .._cacheables import maybe_open_context
 from ..calc import humanize
 from ..data._sharedmem import (
     ShmArray,
+    _Token,
     try_read,
 )
 from ._chart import (
@@ -367,6 +368,7 @@ class FspAdmin:
             tuple,
             tuple[tractor.MsgStream, ShmArray]
         ] = {}
+        self._flow_registry: dict[_Token, str] = {}
         self.src_shm = src_shm
 
     def rr_next_portal(self) -> tractor.Portal:
@@ -411,6 +413,11 @@ class FspAdmin:
 
                 loglevel=loglevel,
                 zero_on_step=conf.get('zero_on_step', False),
+                shm_registry=[
+                    (token.as_msg(), fsp_name, dst_token.as_msg())
+                    for (token, fsp_name), dst_token
+                    in self._flow_registry.items()
+                ],
 
             ) as (ctx, last_index),
             ctx.open_stream() as stream,
@@ -443,11 +450,15 @@ class FspAdmin:
         fqsn = self.linked.symbol.front_feed()
 
         # allocate an output shm array
-        dst_shm, opened = maybe_mk_fsp_shm(
+        key, dst_shm, opened = maybe_mk_fsp_shm(
             '.'.join(fqsn),
             target=target,
             readonly=True,
         )
+        self._flow_registry[
+            (self.src_shm._token, target.name)
+        ] = dst_shm._token
+
         # if not opened:
         #     raise RuntimeError(
         #         f'Already started FSP `{fqsn}:{func_name}`'
@@ -675,14 +686,6 @@ async def open_vlm_displays(
             # had this before??
             # dolla_vlm,
 
-            # spawn and overlay $ vlm on the same subchart
-            fr_shm, started = await admin.start_engine_task(
-                flow_rates,
-                {  # fsp engine conf
-                    'func_name': 'flow_rates',
-                },
-                # loglevel,
-            )
             tasks_ready.append(started)
             # profiler(f'created shm for fsp actor: {display_name}')
 
@@ -753,7 +756,17 @@ async def open_vlm_displays(
             ##################
             # Vlm rate overlay
             ##################
+            # spawn and overlay $ vlm on the same subchart
+            fr_shm, started = await admin.start_engine_task(
+                flow_rates,
+                {  # fsp engine conf
+                    'func_name': 'flow_rates',
+                },
+                # loglevel,
+            )
+            await started.wait()
             trade_rate_color = vlm_rate_color = 'i3'
+
             fr_pi = chart.overlay_plotitem(
                 'vlm_rates',
                 index=0,  # place axis on inside (nearest to chart)