Start working toward a more general (on-demand) pub-sub system which
can be brought into ``tractor``. Right now this just means making
the code in the `fan_out_to_ctxs()` less specific but, eventually
I think this function should be coupled with a decorator and shipped
as a standard "message pattern".
Additionally,
- try out making `BrokerFeed` a `@dataclass`
- strip out all the `trio.Event` / uneeded nursery / extra task crap
from `start_quote_stream()`
This allows for using a monitor to select the current option chain
symbol!
The deats:
- start a bg task which streams the monitor selected symbol
- dynamically repopulate expiry buttons on a newly published symbol
- move static widget creation into a chain method to avoid multiple
quotes requests at startup
- rename a bunch of methods
If quotes are pushed using the adjusted contract symbol (i.e. with
trailing '-1' suffix) the subscriber won't receive them under the
normal symbol. The logic was wrong for determining whether to add
a suffix (was failing for any symbol with an exchange suffix)
which was causing normal data feed subscriptions to fail to match
in every case.
I did some testing of the `optionsIds` parameter to the option quote
endpoint and found that it limits you to 100 symbols so it's not
practical for real-time "all-strike"" chain updating; we have to stick
to filters for now. The only real downside of this is that it seems
multiple filters across multiple symbols is quite latent. I need to
toy with it more to be sure it's not something slow on the client side.
Oh, and store option contract to ids in a `dict` for now as we may want
to try the `optionsIds` thing again down the road as I coordinate with
the QT tech team.
This is an optimization to improve performance when the UI is fed real
time data. Instead of resorting all rows on every quote update, only
re-render when the sort key appears in the quote data, and further, only
resort rows which are changed using bisection based widget insertion to
avoid having `kivy` re-add widgets (and thus re-render graphics) more
often than absolutely necessary.
There's still a ton to polish (and some bugs to fix) but this is a first
working draft of a real-time option chain!
Insights and todos:
- `kivy` widgets need to be cached and reused (eg. rows, cells, etc.)
for speed since it seems creating new ones constantly is quite taxing
on the CPU
- the chain will tear down and re-setup the option data feed stream each
time a different contract expiry button set is clicked
- there's still some weird bug with row highlighting where it seems rows
added from a new expiry set (which weren't previously rendered) aren't
being highlighted reliably
`Row`:
- `no_cell`: support a list of keys for which no cells will be created
- allow passing in a `cell_type` at instantiation
`TickerTable`:
- keep track of rendered rows via a private `_rendered` set
- don't create rows inside `append_row()` expect caller to do it
- never render already rendered widgets in `render_rows()`
Miscellaneous:
- generalize `update_quotes()` to not be tied to specific quote fields
and allow passing in a quote `formatter()` func
- don't bother creating a nursery block until necessary in main
- more commenting
Add some extra fields to each quote that QT should already be
providing (instead of hiding them in the symbol and request contract
info); namely, the expiry and contact type (i.e. put or call).
Define the base set of fields to be displayed in an option chain
UI and add a quote formatter.
Tyler Goodlet
goodboy