First stage port of `.data.feed` to `MktPair`

Add `MktPair` handling block for when a backend delivers
a `mkt_info`-field containing init msg. Adjust the original
`Symbol`-style `'symbol_info'` msg processing to do `Decimal` defaults
and convert to `MktPair` including slapping in a hacky `_atype: str`
field XD

General initial name changes to `bs_mktid` and `_fqme` throughout!

piker/data/feed.py

@@ -26,6 +26,7 @@ from collections import (
     Counter,
 )
 from contextlib import asynccontextmanager as acm
+from decimal import Decimal
 from datetime import datetime
 from functools import partial
 import time
@@ -71,8 +72,10 @@ from ._sharedmem import (
 from .ingest import get_ingestormod
 from .types import Struct
 from ..accounting._mktinfo import (
+    Asset,
+    MktPair,
+    unpack_fqme,
     Symbol,
-    unpack_fqsn,
 )
 from ._source import base_iohlc_dtype
 from ..ui import _search
@@ -565,7 +568,7 @@ async def tsdb_backfill(
             timeframe=timeframe,
         )
 
-        broker, symbol, expiry = unpack_fqsn(fqsn)
+        broker, symbol, expiry = unpack_fqme(fqsn)
         try:
             (
                 latest_start_dt,
@@ -1009,17 +1012,44 @@ async def allocate_persistent_feed(
 
     # the broker-specific fully qualified symbol name,
     # but ensure it is lower-cased for external use.
-    bfqsn = msg['fqsn'].lower()
+    bs_mktid = msg['fqsn'].lower()
 
-    # true fqsn including broker/provider suffix
-    fqsn = '.'.join((bfqsn, brokername))
-    # msg['fqsn'] = bfqsn
+    # true fqme including broker/provider suffix
+    fqme = '.'.join((bs_mktid, brokername))
 
-    symbol = Symbol.from_fqsn(
-        fqsn=fqsn,
-        info=msg['symbol_info'],
+    mktinfo = msg.get('mkt_info')
+    if not mktinfo:
+
+        mktinfo = msg['symbol_info']
+
+        # TODO: read out renamed/new tick size fields in block below!
+        price_tick = mktinfo.get(
+            'price_tick_size',
+            Decimal('0.01'),
         )
-    assert symbol.type_key
+        size_tick = mktinfo.get(
+            'lot_tick_size',
+            Decimal('0.0'),
+        )
+
+        log.warning(f'FQME: {fqme} -> backend needs port to `MktPair`')
+        mkt = MktPair.from_fqme(
+            fqme,
+            price_tick=price_tick,
+            size_tick=size_tick,
+            bs_mktid=bs_mktid,
+
+            _atype=mktinfo['asset_type']
+        )
+
+    else:
+        # the new msg-protocol is to expect an already packed
+        # ``Asset`` and ``MktPair`` object from the backend
+        mkt = mktinfo
+        assert isinstance(mkt, MktPair)
+        assert isinstance(mkt.dst, Asset)
+
+    assert mkt.type_key
 
     # HISTORY storage, run 2 tasks:
     # - a history loader / maintainer
@@ -1040,17 +1070,24 @@ async def allocate_persistent_feed(
         manage_history,
         mod,
         bus,
-        fqsn,
+        fqme,
         some_data_ready,
         feed_is_live,
     )
 
     # yield back control to starting nursery once we receive either
     # some history or a real-time quote.
-    log.info(f'waiting on history to load: {fqsn}')
+    log.info(f'waiting on history to load: {fqme}')
     await some_data_ready.wait()
 
+    symbol = Symbol.from_fqsn(
+        fqsn=fqme,
+        info=msg['symbol_info'],
+    )
     flume = Flume(
+        # TODO: we have to use this for now since currently the
+        # MktPair above doesn't render the correct output key it seems
+        # when we provide the `MktInfo` here?..?
         symbol=symbol,
         first_quote=first_quote,
         _rt_shm_token=rt_shm.token,
@@ -1061,7 +1098,7 @@ async def allocate_persistent_feed(
 
     # for ambiguous names we simply apply the retreived
     # feed to that name (for now).
-    bus.feeds[symstr] = bus.feeds[bfqsn] = flume
+    bus.feeds[symstr] = bus.feeds[bs_mktid] = flume
 
     task_status.started()
 
@@ -1104,7 +1141,7 @@ async def allocate_persistent_feed(
     # start sample loop and shm incrementer task for OHLC style sampling
     # at the above registered step periods.
     try:
-        log.info(f'Starting sampler task for {fqsn}')
+        log.info(f'Starting sampler task for {fqme}')
         await sample_and_broadcast(
             bus,
             rt_shm,
@@ -1114,7 +1151,7 @@ async def allocate_persistent_feed(
             sum_tick_vlm
         )
     finally:
-        log.warning(f'{fqsn} feed task terminated')
+        log.warning(f'{fqme} feed task terminated')
 
 
 @tractor.context
@@ -1197,22 +1234,22 @@ async def open_feed_bus(
         # subscriber
         flume = bus.feeds[symbol]
         sym = flume.symbol
-        bfqsn = sym.key
+        bs_mktid = sym.key
         fqsn = sym.fqsn  # true fqsn
-        assert bfqsn in fqsn and brokername in fqsn
+        assert bs_mktid in fqsn and brokername in fqsn
 
         if sym.suffix:
-            bfqsn = fqsn.removesuffix(f'.{brokername}')
-            log.warning(f'{brokername} expanded symbol {symbol} -> {bfqsn}')
+            bs_mktid = fqsn.removesuffix(f'.{brokername}')
+            log.warning(f'{brokername} expanded symbol {symbol} -> {bs_mktid}')
 
         # pack for ``.started()`` sync msg
         flumes[fqsn] = flume
 
-        # we use the broker-specific fqsn (bfqsn) for
-        # the sampler subscription since the backend isn't (yet)
-        # 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, set())
+        # we use the broker-specific market id (bs_mktid) for the
+        # sampler subscription since the backend isn't (yet) 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(bs_mktid, set())
 
     # sync feed subscribers with flume handles
     await ctx.started(
@@ -1276,9 +1313,9 @@ async def open_feed_bus(
             # maybe use the current task-id to key the sub list that's
             # added / removed? Or maybe we can add a general
             # pause-resume by sub-key api?
-            bfqsn = fqsn.removesuffix(f'.{brokername}')
-            local_subs.setdefault(bfqsn, set()).add(sub)
-            bus.add_subs(bfqsn, {sub})
+            bs_mktid = fqsn.removesuffix(f'.{brokername}')
+            local_subs.setdefault(bs_mktid, set()).add(sub)
+            bus.add_subs(bs_mktid, {sub})
 
         # sync caller with all subs registered state
         sub_registered.set()
@@ -1291,16 +1328,16 @@ async def open_feed_bus(
             async for msg in stream:
 
                 if msg == 'pause':
-                    for bfqsn, subs in local_subs.items():
+                    for bs_mktid, subs in local_subs.items():
                         log.info(
-                            f'Pausing {bfqsn} feed for {uid}')
-                        bus.remove_subs(bfqsn, subs)
+                            f'Pausing {bs_mktid} feed for {uid}')
+                        bus.remove_subs(bs_mktid, subs)
 
                 elif msg == 'resume':
-                    for bfqsn, subs in local_subs.items():
+                    for bs_mktid, subs in local_subs.items():
                         log.info(
-                            f'Resuming {bfqsn} feed for {uid}')
-                        bus.add_subs(bfqsn, subs)
+                            f'Resuming {bs_mktid} feed for {uid}')
+                        bus.add_subs(bs_mktid, subs)
 
                 else:
                     raise ValueError(msg)
@@ -1314,8 +1351,8 @@ async def open_feed_bus(
                 cs.cancel()
 
             # drop all subs for this task from the bus
-            for bfqsn, subs in local_subs.items():
-                bus.remove_subs(bfqsn, subs)
+            for bs_mktid, subs in local_subs.items():
+                bus.remove_subs(bs_mktid, subs)
 
 
 class Feed(Struct):
@@ -1512,7 +1549,7 @@ async def open_feed(
     feed = Feed()
 
     for fqsn in fqsns:
-        brokername, key, suffix = unpack_fqsn(fqsn)
+        brokername, key, suffix = unpack_fqme(fqsn)
         bfqsn = fqsn.replace('.' + brokername, '')
 
         try: