Fix partial-frame-missing backfill logic

This had a bug prior where the end of a frame (a partial) wasn't being
sliced correctly and we'd get odd gaps showing up in the backfilled from
`brokerd` vs. tsdb end index. Repair this by doing timeframe aware index
diffing in `diff_history()` which seems to resolve it. Also, use the
frame-result's `end_dt: datetime` for the loop exit condition.

piker/data/feed.py

@@ -208,39 +208,50 @@ async def _setup_persistent_brokerd(
 
 
 def diff_history(
-    array,
+    array: np.ndarray,
-    start_dt,
+    timeframe: int,
-    end_dt,
+    start_dt: datetime,
-    last_tsdb_dt: Optional[datetime] = None
+    end_dt: datetime,
+    last_tsdb_dt: datetime | None = None
 
 ) -> np.ndarray:
 
+    # no diffing with tsdb dt index possible..
+    if last_tsdb_dt is None:
+        return array
+
+    time_attr = {
+        1: 'seconds',
+        60: 'minutes',
+    }[timeframe]
+    i_diff = getattr((end_dt - last_tsdb_dt), time_attr)
+
+    # if we detect a partial frame's worth of data
+    # that is new, slice out only that history and
+    # write to shm.
+    if i_diff < 0:
+        # empty case since tsdb already has this history
+        return array[:0]
+
+    ln = len(array)
     to_push = array
 
-    if last_tsdb_dt:
+    if i_diff < ln:
-        s_diff = (start_dt - last_tsdb_dt).seconds
+        # slice out missing history from end of frame
+        to_push = array[ln - i_diff:ln]
 
-        # if we detect a partial frame's worth of data
+    # XXX: OLD GAP HANDLING..if there's a gap in a partial frame
-        # that is new, slice out only that history and
+    # worth. we don't need this any more with the timeframe aware
-        # write to shm.
+    # diffing above right?
-        if (
+    # else:
-            s_diff < 0
+    #     # pass back only the portion of the array that is
-        ):
+    #     # greater then the last time stamp in the tsdb.
-            if abs(s_diff) < len(array):
+    #     time = array['time']
-                # the + 1 is because ``last_tsdb_dt`` is pulled from
+    #     to_push = array[time >= last_tsdb_dt.timestamp()]
-                # the last row entry for the ``'time'`` field retreived
-                # from the tsdb.
-                to_push = array[abs(s_diff) + 1:]
 
-            else:
+    log.debug(
-                # pass back only the portion of the array that is
+        f'Pushing partial frame {to_push.size} to shm'
-                # greater then the last time stamp in the tsdb.
+    )
-                time = array['time']
-                to_push = array[time >= last_tsdb_dt.timestamp()]
-
-            log.debug(
-                f'Pushing partial frame {to_push.size} to shm'
-            )
 
     return to_push
 
@@ -286,6 +297,7 @@ async def start_backfill(
 
         to_push = diff_history(
             array,
+            timeframe,
             start_dt,
             end_dt,
             last_tsdb_dt=last_tsdb_dt,
@@ -334,12 +346,12 @@ async def start_backfill(
                     60: {'years': 6},
                 }
 
-            kwargs = periods[step_size_s]
+            period_duration = periods[step_size_s]
 
             # NOTE: manually set the "latest" datetime which we intend to
             # backfill history "until" so as to adhere to the history
             # settings above when the tsdb is detected as being empty.
-            last_tsdb_dt = start_dt.subtract(**kwargs)
+            last_tsdb_dt = start_dt.subtract(**period_duration)
 
         # configure async query throttling
         # rate = config.get('rate', 1)
@@ -353,7 +365,7 @@ async def start_backfill(
         # inline sequential loop where we simply pass the
         # last retrieved start dt to the next request as
         # it's end dt.
-        while start_dt > last_tsdb_dt:
+        while end_dt > last_tsdb_dt:
             log.debug(
                 f'Requesting {step_size_s}s frame ending in {start_dt}'
             )
@@ -363,6 +375,8 @@ async def start_backfill(
                     timeframe,
                     end_dt=start_dt,
                 )
+                # if timeframe == 1:
+                #     await tractor.breakpoint()
 
             # broker says there never was or is no more history to pull
             except DataUnavailable:
@@ -404,6 +418,7 @@ async def start_backfill(
 
             to_push = diff_history(
                 array,
+                timeframe,
                 start_dt,
                 end_dt,
                 last_tsdb_dt=last_tsdb_dt,
@@ -424,6 +439,9 @@ async def start_backfill(
                 log.info(
                     f'Shm buffer overrun on: {start_dt} -> {end_dt}?'
                 )
+                # can't push the entire frame? so
+                # push only the amount that can fit..
+                await tractor.breakpoint()
                 break
 
             log.info(
@@ -510,6 +528,8 @@ async def tsdb_backfill(
 
     # start history anal and load missing new data via backend.
     for timeframe, shm in shms.items():
+        # loads a (large) frame of data from the tsdb depending
+        # on the db's query size limit.
         tsdb_history, first_tsdb_dt, last_tsdb_dt = await storage.load(
             fqsn,
             timeframe=timeframe,
@@ -586,29 +606,45 @@ async def tsdb_backfill(
         if bf_done:
             await bf_done.wait()
 
-        # Load tsdb history into shm buffer (for display).
-
         # TODO: eventually it'd be nice to not require a shm array/buffer
         # to accomplish this.. maybe we can do some kind of tsdb direct to
         # graphics format eventually in a child-actor?
 
-        # do diff against last start frame of history and only fill
-        # in from the tsdb an allotment that allows for most recent
-        # to be loaded into mem *before* tsdb data.
-        if last_tsdb_dt and latest_start_dt:
-            dt_diff_s = (
-                latest_start_dt - last_tsdb_dt
-            ).seconds
-        else:
-            dt_diff_s = 0
-
         # TODO: see if there's faster multi-field reads:
         # https://numpy.org/doc/stable/user/basics.rec.html#accessing-multiple-fields
         # re-index  with a `time` and index field
         prepend_start = shm._first.value
+        shm_last_dt = pendulum.from_timestamp(shm.array[0]['time'])
 
-        # sanity check on most-recent-data loading
+        if last_tsdb_dt:
-        assert prepend_start > dt_diff_s
+            assert shm_last_dt >= last_tsdb_dt
+
+        # do diff against start index of last frame of history and only
+        # fill in an amount of datums from tsdb allows for most recent
+        # to be loaded into mem *before* tsdb data.
+        if (
+            last_tsdb_dt
+            and latest_start_dt
+        ):
+            backfilled_size_s = (
+                latest_start_dt - last_tsdb_dt
+            ).seconds
+        else:
+            backfilled_size_s = (
+                latest_start_dt - shm_last_dt
+            ).seconds
+
+        # Load TSDB history into shm buffer (for display) if there is
+        # remaining buffer space.
+
+        # if the shm buffer len is not large enough to contain
+        # all missing data between the most recent backend-queried frame
+        # and the most recent dt-index in the db we warn that we only
+        # want to load a portion of the next tsdb query to fill that
+        # space.
+        log.info(
+            f'{backfilled_size_s} seconds worth of {timeframe}s data loaded'
+        )
 
         if (
             len(tsdb_history)
@@ -1266,7 +1302,6 @@ async def open_feed_bus(
         # expected to append it's own name to the fqsn, so we filter
         # on keys which *do not* include that name (e.g .ib) .
         bus._subscribers.setdefault(bfqsn, [])
-        # await tractor.breakpoint()
 
     # sync feed subscribers with flume handles
     await ctx.started(