Add epoch time index to fsp buffers

piker/fsp/_api.py

@@ -199,7 +199,10 @@ def maybe_mk_fsp_shm(
     # TODO: load output types from `Fsp`
     # - should `index` be a required internal field?
     fsp_dtype = np.dtype(
-        [('index', int)] +
+        [('index', int)]
+        +
+        [('time', float)]
+        +
         [(field_name, float) for field_name in target.outputs]
     )
 

piker/fsp/_engine.py

@@ -132,7 +132,10 @@ async def fsp_compute(
     fields.pop('index')
     history: Optional[np.ndarray] = None  # TODO: nptyping here!
 
-    if fields and len(fields) > 1 and fields:
+    if (
+        fields and
+        len(fields) > 1
+    ):
         if not isinstance(history_output, dict):
             raise ValueError(
                 f'`{func_name}` is a multi-output FSP and should yield a '
@@ -217,8 +220,14 @@ async def fsp_compute(
 
                 log.debug(f"{func_name}: {processed}")
                 key, output = processed
-                index = src.index
-                dst.array[-1][key] = output
+                # dst.array[-1][key] = output
+                dst.array[[key, 'time']][-1] = (
+                    output,
+                    # TODO: what about pushing ``time.time_ns()``
+                    # in which case we'll need to round at the graphics
+                    # processing / sampling layer?
+                    src.array[-1]['time']
+                )
 
                 # NOTE: for now we aren't streaming this to the consumer
                 # stream latest array index entry which basically just acts
@@ -229,6 +238,7 @@ async def fsp_compute(
                 # N-consumers who subscribe for the real-time output,
                 # which we'll likely want to implement using local-mem
                 # chans for the fan out?
+                # index = src.index
                 # if attach_stream:
                 #     await client_stream.send(index)
 
@@ -388,7 +398,8 @@ async def cascade(
                     src: ShmArray,
                     dst: ShmArray
                 ) -> tuple[bool, int, int]:
-                    '''Predicate to dertmine if a destination FSP
+                    '''
+                    Predicate to dertmine if a destination FSP
                     output array is aligned to its source array.
 
                     '''
@@ -406,11 +417,9 @@ async def cascade(
                     ), step_diff, len_diff
 
                 async def poll_and_sync_to_step(
-
                     tracker: TaskTracker,
                     src: ShmArray,
                     dst: ShmArray,
-
                 ) -> tuple[TaskTracker, int]:
 
                     synced, step_diff, _ = is_synced(src, dst)
@@ -469,4 +478,15 @@ async def cascade(
                         else:
                             last = array[-1:].copy()
 
+                        # sync with source time step
+                        src_t = src.array['time'][-1]
+                        last['time'] = src_t
+
                         dst.push(last)
+
+                        # dst_t = dst.array['time'][-1]
+                        # print(
+                        #     f'{dst.token}\n'
+                        #     f'src: {src_t}\n'
+                        #     f'dst: {dst_t}\n'
+                        # )