Merge pull request #250 from pikers/single_display_update_loop

Single display update loop

piker/data/feed.py

@@ -34,7 +34,6 @@ import trio
 from trio.abc import ReceiveChannel
 from trio_typing import TaskStatus
 import tractor
-# from tractor import _broadcast
 from pydantic import BaseModel
 
 from ..brokers import get_brokermod
@@ -252,7 +251,7 @@ async def allocate_persistent_feed(
 
 
 @tractor.context
-async def attach_feed_bus(
+async def open_feed_bus(
 
     ctx: tractor.Context,
     brokername: str,
@@ -512,7 +511,7 @@ async def open_feed(
 
         portal.open_context(
 
-            attach_feed_bus,
+            open_feed_bus,
             brokername=brokername,
             symbol=sym,
             loglevel=loglevel,

piker/fsp/_engine.py

@@ -90,7 +90,7 @@ async def fsp_compute(
     func_name: str,
     func: Callable,
 
-    attach_stream: bool = True,
+    attach_stream: bool = False,
     task_status: TaskStatus[None] = trio.TASK_STATUS_IGNORED,
 
 ) -> None:

piker/ui/_app.py

@@ -85,11 +85,11 @@ async def _async_main(
     screen = godwidget.window.current_screen()
 
     # configure graphics update throttling based on display refresh rate
-    _display._clear_throttle_rate = min(
+    _display._quote_throttle_rate = min(
         round(screen.refreshRate()),
-        _display._clear_throttle_rate,
+        _display._quote_throttle_rate,
     )
-    log.info(f'Set graphics update rate to {_display._clear_throttle_rate} Hz')
+    log.info(f'Set graphics update rate to {_display._quote_throttle_rate} Hz')
 
     # TODO: do styling / themeing setup
     # _style.style_ze_sheets(godwidget)

piker/ui/_display.py

@@ -15,11 +15,14 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 '''
-Real-time display tasks for charting / graphics.
+real-time display tasks for charting graphics update.
+
+this module ties together quote and computational (fsp) streams with
+graphics update methods via our custom ``pyqtgraph`` charting api.
 
 '''
 from contextlib import asynccontextmanager
-# from pprint import pformat
+from functools import partial
 import time
 from types import ModuleType
 from typing import Optional
@@ -53,45 +56,106 @@ from ..log import get_logger
 
 log = get_logger(__name__)
 
-_clear_throttle_rate: int = 58  # Hz
+# TODO: load this from a config.toml!
-_book_throttle_rate: int = 16  # Hz
+_quote_throttle_rate: int = 58  # Hz
 
 
-async def update_chart_from_quotes(
+def update_fsp_chart(
-
     chart: ChartPlotWidget,
-    stream: tractor.MsgStream,
+    shm: ShmArray,
-    ohlcv: np.ndarray,
+    graphics_name: str,
-
+    array_key: Optional[str],
-    wap_in_history: bool = False,
-    vlm_chart: Optional[ChartPlotWidget] = None,
 
 ) -> None:
-    '''The 'main' (price) chart real-time update loop.
 
-    Receive from the quote stream and update the OHLC chart.
+    array = shm.array
 
-    '''
+    # update graphics
-    # TODO: bunch of stuff:
+    # NOTE: this does a length check internally which allows it
-    # - I'm starting to think all this logic should be
+    # staying above the last row check below..
-    #   done in one place and "graphics update routines"
+    chart.update_curve_from_array(
-    #   should not be doing any length checking and array diffing.
+        graphics_name,
-    # - handle odd lot orders
+        array,
-    # - update last open price correctly instead
+        array_key=array_key or graphics_name,
-    #   of copying it from last bar's close
-    # - 1-5 sec bar lookback-autocorrection like tws does?
-    #   (would require a background history checker task)
-
-    # update last price sticky
-    last_price_sticky = chart._ysticks[chart.name]
-    last_price_sticky.update_from_data(
-        *ohlcv.array[-1][['index', 'close']]
     )
 
-    if vlm_chart:
+    try:
-        vlm_sticky = vlm_chart._ysticks['volume']
+        last_row = array[-1]
+    except IndexError:
+        # XXX: race condition with backfilling shm.
+        #
+        # the underlying issue is that a backfill (aka prepend) and subsequent
+        # shm array first/last index update could result in an empty array
+        # read here since the indices may be updated in such a way that
+        # a read delivers an empty array (though it seems like we
+        # *should* be able to prevent that?). also, as and alt and
+        # something we need anyway, maybe there should be some kind of
+        # signal that a prepend is taking place and this consumer can
+        # respond (eg. redrawing graphics) accordingly.
+        log.warning(f'Read-race on shm array: {graphics_name}@{shm.token}')
+        return
 
-    def maxmin():
+    # TODO: provide a read sync mechanism to avoid this polling. the
+    # underlying issue is that a backfill (aka prepend) and subsequent
+    # shm array first/last index update could result in an empty array
+    # read here since the stream is never torn down on the re-compute
+    # steps.
+    # read_tries = 2
+    # while read_tries > 0:
+    #     try:
+    #         # read last
+    #         array = shm.array
+    #         value = array[-1][array_key]
+    #         break
+
+    #     except IndexError:
+    #         read_tries -= 1
+    #         continue
+
+    # XXX: re: ``array_key``: fsp func names must be unique meaning we
+    # can't have duplicates of the underlying data even if multiple
+    # sub-charts reference it under different 'named charts'.
+
+    # read from last calculated value and update any label
+    last_val_sticky = chart._ysticks.get(graphics_name)
+    if last_val_sticky:
+        # array = shm.array[array_key]
+        # if len(array):
+        #     value = array[-1]
+        last = last_row[array_key]
+        last_val_sticky.update_from_data(-1, last)
+
+
+# _clses = {
+#     'clears': {'trade', 'utrade', 'last'},
+#     'last': {'last'},
+#     'bids': {'bid', 'bsize'},
+#     'asks': {'ask', 'asize'},
+# }
+
+# XXX: idea for frame type data structure we could use on the
+# wire instead of doing it here?
+# frames = {
+#     'index': ['type_a', 'type_c', 'type_n', 'type_n', 'type_c'],
+
+#     'type_a': [tick0, tick1, tick2, .., tickn],
+#     'type_b': [tick0, tick1, tick2, .., tickn],
+#     'type_c': [tick0, tick1, tick2, .., tickn],
+#     ...
+#     'type_n': [tick0, tick1, tick2, .., tickn],
+# }
+
+
+def chart_maxmin(
+    chart: ChartPlotWidget,
+    vlm_chart: Optional[ChartPlotWidget] = None,
+
+) -> tuple[
+    tuple[int, int, int, int],
+    float,
+    float,
+    float,
+]:
     # TODO: implement this
     # https://arxiv.org/abs/cs/0610046
     # https://github.com/lemire/pythonmaxmin
@@ -118,6 +182,45 @@ async def update_chart_from_quotes(
 
     return last_bars_range, mx, max(mn, 0), mx_vlm_in_view
 
+
+async def update_chart_from_quotes(
+
+    linked: LinkedSplits,
+    stream: tractor.MsgStream,
+    ohlcv: np.ndarray,
+
+    wap_in_history: bool = False,
+    vlm_chart: Optional[ChartPlotWidget] = None,
+
+) -> None:
+    '''The 'main' (price) chart real-time update loop.
+
+    Receive from the quote stream and update the OHLC chart.
+
+    '''
+    # TODO: bunch of stuff:
+    # - I'm starting to think all this logic should be
+    #   done in one place and "graphics update routines"
+    #   should not be doing any length checking and array diffing.
+    # - handle odd lot orders
+    # - update last open price correctly instead
+    #   of copying it from last bar's close
+    # - 1-5 sec bar lookback-autocorrection like tws does?
+    #   (would require a background history checker task)
+
+    chart = linked.chart
+
+    # update last price sticky
+    last_price_sticky = chart._ysticks[chart.name]
+    last_price_sticky.update_from_data(
+        *ohlcv.array[-1][['index', 'close']]
+    )
+
+    if vlm_chart:
+        vlm_sticky = vlm_chart._ysticks['volume']
+
+    maxmin = partial(chart_maxmin, chart, vlm_chart)
+
     chart.default_view()
 
     (
@@ -150,21 +253,27 @@ async def update_chart_from_quotes(
     tick_size = chart.linked.symbol.tick_size
     tick_margin = 3 * tick_size
 
-    last_ask = last_bid = last_clear = time.time()
     chart.show()
+    last_quote = time.time()
 
+    # NOTE: all code below this loop is expected to be synchronous
+    # and thus draw instructions are not picked up jntil the next
+    # wait / iteration.
     async for quotes in stream:
 
-        # chart isn't actively shown so just skip render cycle
+        now = time.time()
+        quote_period = now - last_quote
+        if quote_period <= 1/_quote_throttle_rate:
+            log.warning(f'TOO FAST: {1/quote_period}')
+        last_quote = now
+
+        # chart isn't active/shown so skip render cycle and pause feed(s)
         if chart.linked.isHidden():
             await chart.pause_all_feeds()
             continue
 
         for sym, quote in quotes.items():
 
-            now = time.time()
-
-            # brange, mx_in_view, mn_in_view = maxmin()
             (
                 brange,
                 mx_in_view,
@@ -184,6 +293,13 @@ async def update_chart_from_quotes(
             if vlm_chart:
                 # print(f"volume: {end['volume']}")
                 vlm_chart.update_curve_from_array('volume', array)
+
+                # built-in tina $vlm FSP using chl3 typical price for ohlc step
+                # last = array[-1]
+                # chl3 = (last['close'] + last['high'] + last['low']) / 3
+                # v = last['volume']
+                # dv = last['volume'] * chl3
+
                 vlm_sticky.update_from_data(*array[-1][['index', 'volume']])
 
                 if (
@@ -194,30 +310,75 @@ async def update_chart_from_quotes(
                     vlm_chart._set_yrange(yrange=(0, mx_vlm_in_view * 1.375))
                     last_mx_vlm = mx_vlm_in_view
 
-            for tick in quote.get('ticks', ()):
+            ticks_frame = quote.get('ticks', ())
 
-                # log.info(
+            frames_by_type: dict[str, dict] = {}
-                #   f"quotes: {pformat(quote['symbol'])}: {pformat(tick)}")
+            lasts = {}
-                ticktype = tick.get('type')
+
+            # build tick-type "frames" of tick sequences since
+            # likely the tick arrival rate is higher then our
+            # (throttled) quote stream rate.
+            for tick in ticks_frame:
                 price = tick.get('price')
-                size = tick.get('size')
+                ticktype = tick.get('type')
 
                 if ticktype == 'n/a' or price == -1:
                     # okkk..
                     continue
 
-                # clearing price event
+                # keys are entered in olded-event-inserted-first order
-                if ticktype in ('trade', 'utrade', 'last'):
+                # since we iterate ``ticks_frame`` in standard order
+                # above. in other words the order of the keys is the order
+                # of tick events by type from the provider feed.
+                frames_by_type.setdefault(ticktype, []).append(tick)
 
-                    # throttle clearing price updates to ~ max 60 FPS
+                # overwrites so the last tick per type is the entry
-                    period = now - last_clear
+                lasts[ticktype] = tick
-                    if period <= 1/_clear_throttle_rate:
-                        # faster then display refresh rate
-                        continue
 
-                    # print(f'passthrough {tick}\n{1/(now-last_clear)}')
+            # from pprint import pformat
-                    # set time of last graphics update
+            # frame_counts = {
-                    last_clear = now
+            #     typ: len(frame) for typ, frame in frames_by_type.items()
+            # }
+            # print(f'{pformat(frame_counts)}')
+            # print(f'framed: {pformat(frames_by_type)}')
+            # print(f'lasts: {pformat(lasts)}')
+
+            # TODO: eventually we want to separate out the utrade (aka
+            # dark vlm prices) here and show them as an additional
+            # graphic.
+            clear_types = {'trade', 'utrade', 'last'}
+
+            # XXX: if we wanted to iterate in "latest" (i.e. most
+            # current) tick first order as an optimization where we only
+            # update from the last tick from each type class.
+            # last_clear_updated: bool = False
+            # for typ, tick in reversed(lasts.items()):
+
+            # iterate in FIFO order per frame
+            for typ, tick in lasts.items():
+
+                price = tick.get('price')
+                size = tick.get('size')
+
+                # compute max and min prices (including bid/ask) from
+                # tick frames to determine the y-range for chart
+                # auto-scaling.
+                # TODO: we need a streaming minmax algo here, see def above.
+                mx = max(price + tick_margin, mx)
+                mn = min(price - tick_margin, mn)
+
+                if typ in clear_types:
+
+                    # XXX: if we only wanted to update graphics from the
+                    # "current"/"latest received" clearing price tick
+                    # once (see alt iteration order above).
+                    # if last_clear_updated:
+                    #     continue
+
+                    # last_clear_updated = True
+                    # we only want to update grahpics from the *last*
+                    # tick event that falls under the "clearing price"
+                    # set.
 
                     # update price sticky(s)
                     end = array[-1]
@@ -235,33 +396,11 @@ async def update_chart_from_quotes(
                         # update vwap overlay line
                         chart.update_curve_from_array('bar_wap', ohlcv.array)
 
-                # l1 book events
+                # L1 book label-line updates
-                # throttle the book graphics updates at a lower rate
+                # XXX: is this correct for ib?
-                # since they aren't as critical for a manual user
-                # viewing the chart
-
-                elif ticktype in ('ask', 'asize'):
-                    if (now - last_ask) <= 1/_book_throttle_rate:
-                        # print(f'skipping\n{tick}')
-                        continue
-
-                    # print(f'passthrough {tick}\n{1/(now-last_ask)}')
-                    last_ask = now
-
-                elif ticktype in ('bid', 'bsize'):
-                    if (now - last_bid) <= 1/_book_throttle_rate:
-                        continue
-
-                    # print(f'passthrough {tick}\n{1/(now-last_bid)}')
-                    last_bid = now
-
-                # compute max and min trade values to display in view
-                # TODO: we need a streaming minmax algorithm here, see
-                # def above.
-
-                # XXX: prettty sure this is correct?
                 # if ticktype in ('trade', 'last'):
-                if ticktype in ('last',):  # 'size'):
+                # if ticktype in ('last',):  # 'size'):
+                if typ in ('last',):  # 'size'):
 
                     label = {
                         l1.ask_label.fields['level']: l1.ask_label,
@@ -271,23 +410,20 @@ async def update_chart_from_quotes(
                     if label is not None:
                         label.update_fields({'level': price, 'size': size})
 
-                        # on trades should we be knocking down
+                        # TODO: on trades should we be knocking down
                         # the relevant L1 queue?
                         # label.size -= size
 
-                elif ticktype in ('ask', 'asize'):
+                # elif ticktype in ('ask', 'asize'):
+                elif typ in ('ask', 'asize'):
                     l1.ask_label.update_fields({'level': price, 'size': size})
 
-                elif ticktype in ('bid', 'bsize'):
+                # elif ticktype in ('bid', 'bsize'):
+                elif typ in ('bid', 'bsize'):
                     l1.bid_label.update_fields({'level': price, 'size': size})
 
-                # in view y-range checking for auto-scale
+            # check for y-range re-size
-                # update the max/min price in view to keep bid/ask on screen
+            if (mx > last_mx) or (mn < last_mn):
-                mx = max(price + tick_margin, mx)
-                mn = min(price - tick_margin, mn)
-                if (mx > last_mx) or (
-                    mn < last_mn
-                ):
                 # print(f'new y range: {(mn, mx)}')
                 chart._set_yrange(
                     yrange=(mn, mx),
@@ -301,89 +437,63 @@ async def update_chart_from_quotes(
 
             last_mx, last_mn = mx, mn
 
+            # run synchronous update on all derived fsp subplots
+            for name, subchart in linked.subplots.items():
+                update_fsp_chart(
+                    subchart,
+                    subchart._shm,
 
-async def fan_out_spawn_fsp_daemons(
+                    # XXX: do we really needs seperate names here?
+                    name,
+                    array_key=name,
+                )
 
-    linkedsplits: LinkedSplits,
+                # TODO: all overlays on all subplots..
-    fsps: dict[str, str],
+
+            # run synchronous update on all derived overlays
+            for curve_name, shm in chart._overlays.items():
+                update_fsp_chart(
+                    chart,
+                    shm,
+                    curve_name,
+                    array_key=curve_name,
+                )
+
+
+def maybe_mk_fsp_shm(
     sym: str,
-    src_shm: list,
+    field_name: str,
-    brokermod: ModuleType,
+    display_name: Optional[str] = None,
-    group_status_key: str,
+    readonly: bool = True,
-    loglevel: str,
 
-) -> None:
+) -> (ShmArray, bool):
-    '''Create financial signal processing sub-actors (under flat tree)
+    '''Allocate a single row shm array for an symbol-fsp pair if none
-    for each entry in config and attach to local graphics update tasks.
+    exists, otherwise load the shm already existing for that token.
-
-    Pass target entrypoint and historical data.
 
     '''
-    linkedsplits.focus()
-
     uid = tractor.current_actor().uid
-
+    if not display_name:
-    # spawns sub-processes which execute cpu bound FSP code
+        display_name = field_name
-    async with (
-        tractor.open_nursery() as n,
-        trio.open_nursery() as ln,
-    ):
-
-        # Currently we spawn an actor per fsp chain but
-        # likely we'll want to pool them eventually to
-        # scale horizonatlly once cores are used up.
-        for display_name, conf in fsps.items():
-
-            fsp_func_name = conf['fsp_func_name']
 
     # TODO: load function here and introspect
     # return stream type(s)
 
     # TODO: should `index` be a required internal field?
-            fsp_dtype = np.dtype([('index', int), (fsp_func_name, float)])
+    fsp_dtype = np.dtype([('index', int), (field_name, float)])
 
     key = f'{sym}.fsp.{display_name}.{".".join(uid)}'
 
-            # this is all sync currently
     shm, opened = maybe_open_shm_array(
         key,
         # TODO: create entry for each time frame
         dtype=fsp_dtype,
         readonly=True,
     )
-
+    return shm, opened
-            # XXX: fsp may have been opened by a duplicate chart.
-            # Error for now until we figure out how to wrap fsps as
-            # "feeds".  assert opened, f"A chart for {key} likely
-            # already exists?"
-
-            conf['shm'] = shm
-
-            portal = await n.start_actor(
-                enable_modules=['piker.fsp._engine'],
-                name='fsp.' + display_name,
-            )
-
-            # init async
-            ln.start_soon(
-                run_fsp,
-                portal,
-                linkedsplits,
-                brokermod,
-                sym,
-                src_shm,
-                fsp_func_name,
-                display_name,
-                conf,
-                group_status_key,
-                loglevel,
-            )
-
-    # blocks here until all fsp actors complete
 
 
 @asynccontextmanager
-async def open_sidepane(
+async def open_fsp_sidepane(
 
     linked: LinkedSplits,
     conf: dict[str, dict[str, str]],
@@ -403,8 +513,11 @@ async def open_sidepane(
             }
 
         # add parameters for selection "options"
-        defaults = config.get('params', {})
+        params = config.get('params', {})
-        for name, default in defaults.items():
+        for name, config in params.items():
+
+            default = config['default_value']
+            kwargs = config.get('widget_kwargs', {})
 
             # add to ORM schema
             schema.update({
@@ -412,6 +525,7 @@ async def open_sidepane(
                     'label': f'**{name}**:',
                     'type': 'edit',
                     'default_value': default,
+                    'kwargs': kwargs,
                 },
             })
 
@@ -424,7 +538,7 @@ async def open_sidepane(
     FspConfig = create_model(
         'FspConfig',
         name=display_name,
-        **defaults,
+        **params,
     )
     sidepane.model = FspConfig()
 
@@ -444,16 +558,96 @@ async def open_sidepane(
         yield sidepane
 
 
-async def run_fsp(
+async def open_fspd_cluster(
+
+    linkedsplits: LinkedSplits,
+    fsps: dict[str, str],
+    sym: str,
+    src_shm: list,
+    brokermod: ModuleType,
+    group_status_key: str,
+    loglevel: str,
+
+    # this con
+    display_in_own_task: bool = False,
+
+) -> None:
+    '''Create sub-actors (under flat tree)
+    for each entry in config and attach to local graphics update tasks.
+
+    Pass target entrypoint and historical data.
+
+    '''
+    linkedsplits.focus()
+
+    # spawns sub-processes which execute cpu bound fsp work
+    # which is streamed back to this parent.
+    async with (
+        tractor.open_nursery() as n,
+        trio.open_nursery() as ln,
+    ):
+        # Currently we spawn an actor per fsp chain but
+        # likely we'll want to pool them eventually to
+        # scale horizonatlly once cores are used up.
+        for display_name, conf in fsps.items():
+
+            func_name = conf['func_name']
+
+            shm, opened = maybe_mk_fsp_shm(
+                sym,
+                field_name=func_name,
+                display_name=display_name,
+                readonly=True,
+            )
+
+            # XXX: fsp may have been opened by a duplicate chart.
+            # Error for now until we figure out how to wrap fsps as
+            # "feeds".  assert opened, f"A chart for {key} likely
+            # already exists?"
+
+            portal = await n.start_actor(
+                enable_modules=['piker.fsp._engine'],
+                name='fsp.' + display_name,
+            )
+
+            # init async
+            ln.start_soon(
+                partial(
+                    update_chart_from_fsp,
+
+                    portal,
+                    linkedsplits,
+                    brokermod,
+                    sym,
+                    src_shm,
+                    func_name,
+                    display_name,
+                    conf=conf,
+                    shm=shm,
+                    is_overlay=conf.get('overlay', False),
+                    group_status_key=group_status_key,
+                    loglevel=loglevel,
+                )
+            )
+
+    # blocks here until all fsp actors complete
+
+
+async def update_chart_from_fsp(
+
+    portal: tractor.Portal,
 
-    portal: tractor._portal.Portal,
     linkedsplits: LinkedSplits,
     brokermod: ModuleType,
     sym: str,
     src_shm: ShmArray,
-    fsp_func_name: str,
+    func_name: str,
     display_name: str,
     conf: dict[str, dict],
+
+    shm: ShmArray,
+    is_overlay: bool,
+
     group_status_key: str,
     loglevel: str,
 
@@ -478,22 +672,17 @@ async def run_fsp(
             # name as title of sub-chart
             brokername=brokermod.name,
             src_shm_token=src_shm.token,
-            dst_shm_token=conf['shm'].token,
+            dst_shm_token=shm.token,
             symbol=sym,
-            func_name=fsp_func_name,
+            func_name=func_name,
             loglevel=loglevel,
 
         ) as (ctx, last_index),
         ctx.open_stream() as stream,
-        open_sidepane(
+
-            linkedsplits,
+        open_fsp_sidepane(linkedsplits, {display_name: conf},) as sidepane,
-            {display_name: conf},
-        ) as sidepane,
     ):
-
+        if is_overlay:
-        shm = conf['shm']
-
-        if conf.get('overlay'):
             chart = linkedsplits.chart
             chart.draw_curve(
                 name=display_name,
@@ -501,15 +690,15 @@ async def run_fsp(
                 overlay=True,
                 color='default_light',
             )
-            last_val_sticky = None
+            # specially store ref to shm for lookup in display loop
+            chart._overlays[display_name] = shm
 
         else:
-
             chart = linkedsplits.add_plot(
                 name=display_name,
                 array=shm.array,
 
-                array_key=conf['fsp_func_name'],
+                array_key=conf['func_name'],
                 sidepane=sidepane,
 
                 # curve by default
@@ -528,30 +717,17 @@ async def run_fsp(
             # should **not** be the same sub-chart widget
             assert chart.name != linkedsplits.chart.name
 
-            # sticky only on sub-charts atm
+        array_key = func_name
-            last_val_sticky = chart._ysticks[chart.name]
 
-            # read from last calculated value
+        # first UI update, usually from shm pushed history
-            array = shm.array
+        update_fsp_chart(
-
+            chart,
-            # XXX: fsp func names must be unique meaning we don't have
+            shm,
-            # duplicates of the underlying data even if multiple
-            # sub-charts reference it under different 'named charts'.
-            value = array[fsp_func_name][-1]
-
-            last_val_sticky.update_from_data(-1, value)
-
-        chart.linked.focus()
-
-        # works also for overlays in which case data is looked up from
-        # internal chart array set....
-        chart.update_curve_from_array(
             display_name,
-            shm.array,
+            array_key=array_key,
-            array_key=fsp_func_name
         )
 
-        chart.linked.resize_sidepanes()
+        chart.linked.focus()
 
         # TODO: figure out if we can roll our own `FillToThreshold` to
         # get brush filled polygons for OS/OB conditions.
@@ -559,11 +735,11 @@ async def run_fsp(
         # generic fills between curve types while ``PlotCurveItem`` has
         # logic inside ``.paint()`` for ``self.opts['fillLevel']`` which
         # might be the best solution?
-        # graphics = chart.update_from_array(chart.name, array[fsp_func_name])
+        # graphics = chart.update_from_array(chart.name, array[func_name])
         # graphics.curve.setBrush(50, 50, 200, 100)
         # graphics.curve.setFillLevel(50)
 
-        if fsp_func_name == 'rsi':
+        if func_name == 'rsi':
             from ._lines import level_line
             # add moveable over-[sold/bought] lines
             # and labels only for the 70/30 lines
@@ -574,54 +750,35 @@ async def run_fsp(
 
         chart._set_yrange()
 
-        last = time.time()
-
         done()
+        chart.linked.resize_sidepanes()
 
-        # i = 0
         # update chart graphics
+        i = 0
+        last = time.time()
         async for value in stream:
 
             # chart isn't actively shown so just skip render cycle
             if chart.linked.isHidden():
-                # print(f'{i} unseen fsp cyclce')
+                print(f'{i} unseen fsp cyclce')
-                # i += 1
+                i += 1
                 continue
 
+            else:
                 now = time.time()
                 period = now - last
 
-            # if period <= 1/30:
+                if period <= 1/_quote_throttle_rate:
-            if period <= 1/_clear_throttle_rate:
                     # faster then display refresh rate
-                # print(f'fsp too fast: {1/period}')
+                    print(f'fsp too fast: {1/period}')
                     continue
 
-            # TODO: provide a read sync mechanism to avoid this polling.
+                # run synchronous update
-            # the underlying issue is that a backfill and subsequent shm
+                update_fsp_chart(
-            # array first/last index update could result in an empty array
+                    chart,
-            # read here since the stream is never torn down on the
+                    shm,
-            # re-compute steps.
-            read_tries = 2
-            while read_tries > 0:
-                try:
-                    # read last
-                    array = shm.array
-                    value = array[-1][fsp_func_name]
-                    break
-
-                except IndexError:
-                    read_tries -= 1
-                    continue
-
-            if last_val_sticky:
-                last_val_sticky.update_from_data(-1, value)
-
-            # update graphics
-            chart.update_curve_from_array(
                     display_name,
-                array,
+                    array_key=func_name,
-                array_key=fsp_func_name,
                 )
 
                 # set time of last graphics update
@@ -668,6 +825,7 @@ async def check_for_new_bars(feed, ohlcv, linkedsplits):
                 just_history=False,
             )
 
+            # main chart overlays
             for name in price_chart._overlays:
 
                 price_chart.update_curve_from_array(
@@ -675,6 +833,7 @@ async def check_for_new_bars(feed, ohlcv, linkedsplits):
                     price_chart._arrays[name]
                 )
 
+            # each subplot
             for name, chart in linkedsplits.subplots.items():
                 chart.update_curve_from_array(
                     chart.name,
@@ -707,12 +866,26 @@ async def maybe_open_vlm_display(
         yield
         return
     else:
-        async with open_sidepane(
+
+        shm, opened = maybe_mk_fsp_shm(
+            linked.symbol.key,
+            '$_vlm',
+            readonly=True,
+        )
+
+        async with open_fsp_sidepane(
             linked, {
                 'volume': {
+
                     'params': {
-                        'price_func': 'ohl3'
+
-                    }
+                        'price_func': {
+                            'default_value': 'ohl3',
+                            # tell target ``Edit`` widget to not allow
+                            # edits for now.
+                            'widget_kwargs': {'readonly': True},
+                        },
+                    },
                 }
             },
         ) as sidepane:
@@ -813,7 +986,7 @@ async def display_symbol_data(
             loglevel=loglevel,
 
             # 60 FPS to limit context switches
-            tick_throttle=_clear_throttle_rate,
+            tick_throttle=_quote_throttle_rate,
 
         ) as feed,
     ):
@@ -868,20 +1041,39 @@ async def display_symbol_data(
 
         # TODO: eventually we'll support some kind of n-compose syntax
         fsp_conf = {
-            # 'rsi': {
+
-            #     'fsp_func_name': 'rsi',
+            'rsi': {
-            #     'params': {'period': 14},
+
-            #     'chart_kwargs': {
+                # literal python func ref lookup name
-            #         'static_yrange': (0, 100),
+                'func_name': 'rsi',
-            #     },
+
-            # },
+                # map of parameters to place on the fsp sidepane widget
+                # which should map to dynamic inputs available to the
+                # fsp function at runtime.
+                'params': {
+                    'period': {
+                        'default_value': 14,
+                        'widget_kwargs': {'readonly': True},
+                    },
+                },
+
+                # ``ChartPlotWidget`` options passthrough
+                'chart_kwargs': {
+                    'static_yrange': (0, 100),
+                },
+            },
+
         }
 
-        if has_vlm(ohlcv):
+        if has_vlm(ohlcv):  # and provider != 'binance':
+            # binance is too fast atm for FSPs until we wrap
+            # the fsp streams as throttled ``Feeds``, see
+            #
+
             # add VWAP to fsp config for downstream loading
             fsp_conf.update({
                 'vwap': {
-                    'fsp_func_name': 'vwap',
+                    'func_name': 'vwap',
                     'overlay': True,
                     'anchor': 'session',
                 },
@@ -900,7 +1092,7 @@ async def display_symbol_data(
         ):
             # load initial fsp chain (otherwise known as "indicators")
             ln.start_soon(
-                fan_out_spawn_fsp_daemons,
+                open_fspd_cluster,
                 linkedsplits,
                 fsp_conf,
                 sym,
@@ -913,7 +1105,7 @@ async def display_symbol_data(
             # start graphics update loop(s)after receiving first live quote
             ln.start_soon(
                 update_chart_from_quotes,
-                chart,
+                linkedsplits,
                 feed.stream,
                 ohlcv,
                 wap_in_history,