The original implementation of `.calc_be_price()` wasn't correct since
the real so called "price per unit" (ppu), is actually defined by
a recurrence relation (which is why the original state-updated
`.lifo_update()` approach worked well) and requires the previous ppu to
be weighted by the new accumulated position size when considering a new
clear event. The ppu is the price that above or below which the trader
takes a win or loss on transacting one unit of the trading asset and
thus it is the true "break even price" that determines making or losing
money per fill. This patches fixes the implementation to use trailing
windows of the accumulated size and ppu to compute the next ppu value
for any new clear event as well as handle rare cases where the
"direction" changes polarity (eg. long to short in a single order). The
new method is `Position.calc_ppu()` and further details of the relation
can be seen in the doc strings.
This patch also includes a wack-ton of clean ups and removals in an
effort to refine position management api for easier use in new backends:
- drop `updaate_pps_conf()`, `load_pps_from_toml()` and rename
`load_trands_from_ledger()` -> `load_pps_from_ledger()`.
- extend `PpTable` to have a `.to_toml()` method which returns the
active set of positions ready to be serialized to the `pps.toml` file
which is collects from calling,
- `PpTable.dump_active()` which now returns double dicts of the
open/closed pp object maps.
- make `Position.minimize_clears()` now iterate the clears table in
chronological order (instead of reverse) and only drop fills prior
to any zero-size state (the old reversed way can result incorrect
history-size-retracement in cases where a position is lessened but
not completely exited).
- drop `Position.add_clear()` and instead just manually add entries
inside `.update_from_trans()` and also add a `accum_size` and `ppu`
field to ever entry thus creating a position "history" sequence of
the ppu and accum size for every position and prepares for being
and to show "position lifetimes" in the UI.
- move fqsn getting into `Position.to_pretoml()`.
Use the new `.calc_[be_price/size]()` methods when serializing to and
from the `pps.toml` format and add an audit method which will warn about
mismatched values and assign the clears table calculated values pre-write.
Drop the `.lifo_update()` method and instead allow both
`.size`/`.be_price` properties to exist (for non-ledger related uses of
`Position`) alongside the new calc methods and only get fussy about
*what* the properties are set to in the case of ledger audits.
Also changes `Position.update()` -> `.add_clear()`.
Since we're going to need them anyway for desired features, add
2 new `Position` methods:
- `.calc_be_price()` which computes the breakeven cost basis price
from the entries in the clears table.
- `.calc_size()` which just sums the clear sizes.
Add a `cost_scalar: float` control to the `.update_from_trans()` method
to allow manual adjustment of the cost weighting for the case where
a "non-symmetrical" model is wanted.
Go back to always trying to write the backing ledger files on exit, even
when there's an error (obvs without the `return` in the `finally:` block
f$#% up).
Can't believe i missed this but any `return` inside a `finally` will
suppress the error from the `try:` part... XD
Thought i was losing my mind when the ledger was mutated and then
an error just after wasn't getting raised.. lul.
Never again...
In order to avoid double transaction adds/updates and too-early-discard
of zero sized pps (like when trades are loaded from a backend broker but
were already added to a ledger or `pps.toml` prior) we now **don't** pop
such `Position` entries from the `.pps` table in order to keep each
position's clears table always in place. This avoids the edge case where
an entry was removed too early (due to zero size) but then duplicate
trade entries that were in that entrie's clears show up from the backend
and are entered into a new entry resulting in an incorrect size in a new
entry..We still only push non-net-zero entries to the `pps.toml`.
More fixes:
- return the updated set of `Positions` from `.lifo_update()`.
- return the full table set from `update_pps()`.
- use `PpTable.update_from_trans()` more throughout.
- always write the `pps.toml` on `open_pps()` exit.
- only return table from `load_pps_from_toml()`.
In an effort to begin allowing backends to have more granular control
over position updates, particular in the case where they need to be
reloaded from a trades ledger, this adds a new table API which can
be loaded using `open_pps()`.
- offer an `.update_trans()` method which takes in a `dict` of
`Transactions` and updates the current table of `Positions` from it.
- add a `.dump_active()` which renders the active pp entries dict in
a format ready for toml serialization and all closed positions since
the last update (we might want to not drop these?)
All other module-function apis currently in use should remain working as
before for the moment.
Change `.find_contract()` -> `.find_contracts()` to allow multi-search
for so called "ambiguous" contracts (like for `Future`s) such that the
method now returns a `list` of tracts and populates the contract cache
with all specific tracts retrieved. Let it take in an (unvalidated)
contract that will be fqsn-style-tokenized such that it can be called
from `.search_symbols()` (though we're not quite yet XD).
More stuff,
- add `Client.parse_patt2fqsn()` which is an fqsn to token unpacker
built from the original logic in the old `.find_contract()`.
- handle fiat/forex pairs with the `'CASH'` sectype.
- add a flag to allow unqualified contracts to fail with a warning msg.
- populate the client's contract cache with all expiries of
an ambiguous derivative.
- allow `.con_deats()` to warn msg instead of raise on def-not-found.
- add commented `assert 0` which was triggering a debugger deadlock in
`tractor` which we still haven't been able to create a unit test for.
Minimize calling `.data._shmarray.attach_shm_array()` as much as is
possible to avoid the crash from #332. This is the suggested hack from
issue #359.
Resolves https://github.com/pikers/piker/issues/359
Tyler Goodlet
goodboy