Start tinkering with `tractor.trionics.ipython_embed()`

In effort to get back to a usable REPL around the mkts client
this adds usage of the new `tractor` integration api as well as logic
for skipping backfilling if existing tsdb arrays are found.

piker/data/feed.py

@@ -192,6 +192,22 @@ async def _setup_persistent_brokerd(
         await trio.sleep_forever()
 
 
+async def start_backfill(
+    mod: ModuleType,
+    fqsn: str,
+    shm: ShmArray,
+
+    task_status: TaskStatus[trio.CancelScope] = trio.TASK_STATUS_IGNORED,
+
+) -> int:
+
+    return await mod.backfill_bars(
+        fqsn,
+        shm,
+        task_status=task_status,
+    )
+
+
 async def manage_history(
     mod: ModuleType,
     bus: _FeedsBus,
@@ -222,7 +238,12 @@ async def manage_history(
     )
 
     log.info('Scanning for existing `marketstored`')
+
     is_up = await check_for_service('marketstored')
+
+    # for now only do backfilling if no tsdb can be found
+    do_backfill = not is_up and opened
+
     if is_up and opened:
         log.info('Found existing `marketstored`')
         from . import marketstore
@@ -231,6 +252,11 @@ async def manage_history(
             fqsn,
         ) as (storage, tsdb_arrays):
 
+            # TODO: get this shit workin
+            from tractor.trionics import ipython_embed
+            await ipython_embed()
+            # await ipython_embed(ns=locals())
+
             # TODO: history validation
             # assert opened, f'Persistent shm for {symbol} was already open?!'
             # if not opened:
@@ -238,6 +264,7 @@ async def manage_history(
             #         "Persistent shm for sym was already open?!"
             #     )
 
+
             if tsdb_arrays:
                 log.info(f'Loaded tsdb history {tsdb_arrays}')
                 fastest = list(tsdb_arrays[fqsn].values())[0]
@@ -272,16 +299,28 @@ async def manage_history(
 
                     last_dt = datetime.fromtimestamp(last_s)
                     array, next_dt = await hist(end_dt=last_dt)
+            else:
+                do_backfill = True
+
+
+                # await tractor.breakpoint()
 
             some_data_ready.set()
 
-    elif opened:
+    if do_backfill:
         log.info('No existing `marketstored` found..')
 
         # start history backfill task ``backfill_bars()`` is
         # a required backend func this must block until shm is
         # filled with first set of ohlc bars
-        _ = await bus.nursery.start(mod.backfill_bars, fqsn, shm)
+        await bus.nursery.start(
+            start_backfill,
+            mod,
+            fqsn,
+            shm,
+        )
+
+        # _ = await bus.nursery.start(mod.backfill_bars, fqsn, shm)
 
     # yield back after client connect with filled shm
     task_status.started(shm)
@@ -366,7 +405,6 @@ async def allocate_persistent_feed(
     bfqsn = init_msg[symbol]['fqsn'].lower()
     init_msg[symbol]['fqsn'] = bfqsn
 
-
     # HISTORY, run 2 tasks:
     # - a history loader / maintainer
     # - a real-time streamer which consumers and sends new data to any