Lookup overlay contents from the OHLC struct array (for now / to make
things work) and fix anchoring logic with better offsets to keep
contents labels super tight to the edge of the view box. Unfortunately,
had to hack the label-height-calc thing for avoiding overlap of graphics
with the label; haven't found a better solution yet and pyqtgraph seems
to require more rabbit holing to figure out something better. Slap in
some inf lines for over[sold/bought] rsi conditions thresholding.
If you have a common broker feed daemon then likely you don't want to
create superfluous shared mem buffers for the same symbol. This adds an
ad hoc little context manger which keeps a bool state of whether
a buffer writer task currently is running in this process. Before we
were checking the shared array token cache and **not** clearing it when
the writer task exited, resulting in incorrect writer/loader logic on
the next entry..
Really, we need a better set of SC semantics around the shared mem stuff
presuming there's only ever one writer per shared buffer at given time.
Hopefully that will come soon!
If we know the max and min in view then on datum updates we can avoid
resizing the y-range when a new max/min has not yet arrived.
This adds a very naive numpy calc in the drawing thread which we can
likely improve with a more efficient streaming alternative which can
also likely be run in a fsp subactor. Also, since this same calc is
essentially done inside `._set_yrange()` we will likely want to allow
passing the result into the method to avoid duplicate work.
This kicks off what will be the beginning of hopefully a very nice
(soft) real-time financial signal processing system. We're keeping the
hack to "time align" curves (for now) with the bars for now by slapping
in an extra datum at index 0.
Just like for the source OHLC, we now have the chart parent actor create
an fsp shm array and use it to read back signal data for plotting.
Some tweaks to get the price chart (and sub-charts) to load historical
datums immediately instead of waiting on an initial quote.
- Move to new shared mem system only writing on the first (by process)
entry to `stream_quotes()`.
- Deliver bars before first quote arrives so that chart can populate and
then wait for initial arrival.
- Allow caching clients per actor.
- Load bars using the same (cached) client that starts the quote stream
thus speeding up initialization.
Wraps the growing tuple of items being delivered by `open_feed()`.
Add lazy loading of the broker's signal step stream with
a `Feed.index_stream()` method.
Add an internal `_Token` to do interchange (un)packing for passing
"references" to shm blocks between actors. Part of the token involves
providing the `numpy.dtype` in a cross-actor format. Add a module
variable for caching "known tokens" per actor. Drop use of context
managers since they tear down shm blocks too soon in debug mode and
there seems to be no reason to unlink/close shm before the process has
terminated; if code needs it torn down explicitly, it can.
Adjust the `data.open_feed()` api to take a shm token so the
broker-daemon can attach a previously created (by the parent actor) mem
buf and push real-time tick data. There's still some sloppiness here in
terms of ensuring only one mem buf per symbol (can be seen in
`stream_quotes()`) which should really managed at the data api level.
Add a bar incrementing stream-task which delivers increment msgs to any
consumers.
Logic in `SharedArray.push()` was totally wrong.
Remove all the `multiprocessing.resource_tracker` crap such that we
aren't loading an extra process at every layer and we don't get tons of
errors when cleaning on in an SC way.
This adds a shared memory "incrementing array" sub-sys interface
for single writer, multi-reader style data passing. The main motivation
is to avoid multiple copies of the same `numpy` array across actors
(plus now we can start being fancy like ray).
There still seems to be some odd issues with the "resource tracker"
complaining at teardown (likely partially to do with SIGINT stuff) so
some further digging in the stdlib code is likely coming.
Pertains to #107 and #98
Added a comment to clarify, ish.
Add `ChartPlotWidget._overlays` as registry of curves added on top of
main graphics. Hackishly (ad-hoc-ishly?) update the curve assuming the
data resides in the same `._array` for now (which it does for historical
vwap).
Tyler Goodlet