Use binary search (bisection) to sort table rows

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.

piker/ui/monitor.py

@@ -8,6 +8,7 @@ Launch with ``piker monitor <watchlist name>``.
 from itertools import chain
 from types import ModuleType, AsyncGeneratorType
 from typing import List, Callable, Dict
+from bisect import bisect
 
 import trio
 import tractor
@@ -19,6 +20,7 @@ from kivy.lang import Builder
 from kivy import utils
 from kivy.app import async_runTouchApp
 from kivy.core.window import Window
+from kivy.properties import BooleanProperty
 
 from ..log import get_logger
 from .pager import PagerView
@@ -69,8 +71,10 @@ _kv = (f'''
     size: self.texture_size
     # color: {colorcode('gray')}
     # font_color: {colorcode('gray')}
-    font_name: 'Roboto-Regular'
+    # font_name: 'Hack-Regular'
-    background_color: [0]*4  # by default transparent; use row color
+    # by default transparent; use row color
+    # if `highlight` is set use i3
+    background_color: {_i3_rgba} if self.click_toggle else [0]*4
     # background_color: {_cell_rgba}
     # spacing: 0, 0
     # padding: [0]*4
@@ -148,6 +152,8 @@ class Cell(Button):
 
     ``key`` is the column name index value.
     """
+    click_toggle = BooleanProperty(False)
+
     def __init__(self, key=None, is_header=False, **kwargs):
         super(Cell, self).__init__(**kwargs)
         self.key = key
@@ -177,7 +183,7 @@ class HeaderCell(Cell):
             # mark this cell as the last selected
             table.last_clicked_col_cell = self
             # sort and render the rows immediately
-            self.row.table.render_rows(table.quote_cache)
+            self.row.table.render_rows(table.symbols2rows.values())
 
         # TODO: make this some kind of small geometry instead
         # (maybe like how trading view does it).
@@ -310,6 +316,9 @@ class Row(GridLayout, HoverBehavior):
     def get_cell(self, key):
         return self._cell_widgets.get(key)
 
+    def get_field(self, key):
+        return self._last_record[key]
+
     def _append_cell(self, text, key, header=False):
         if not len(self._cell_widgets) < self.cols:
             raise ValueError(f"Can not append more then {self.cols} cells")
@@ -378,12 +387,10 @@ class TickerTable(GridLayout):
         super(TickerTable, self).__init__(**kwargs)
         self.symbols2rows = {}
         self.sort_key = sort_key
-        self.quote_cache = {}
-        self.row_filter = lambda item: item
         # for tracking last clicked column header cell
         self.last_clicked_col_cell = None
-        self._last_row_toggle = 0
+        self._symbols2index = {}
-        self._rendered = set()
+        self._sorted = []
 
     def append_row(self, key, row):
         """Append a `Row` of `Cell` objects to this table.
@@ -391,36 +398,51 @@ class TickerTable(GridLayout):
         # store ref to each row
         self.symbols2rows[key] = row
         self.add_widget(row)
+        self._sorted.append(row)
         return row
 
+    def clear(self):
+        self.clear_widgets()
+        self._sorted.clear()
+
     def render_rows(
         self,
-        pairs: Dict[str,  Row],
+        changed: set,
         sort_key: str = None,
-        row_filter=None,
     ):
-        """Sort and render all rows on the ticker grid from ``pairs``.
+        """Sort and render all rows on the ticker grid from ``syms2rows``.
         """
-        self.clear_widgets()
-        self._rendered.clear()
         sort_key = sort_key or self.sort_key
-        # TODO: intead of constantly re-rendering on every
+        key_row_pairs = list(sorted(
-        # change do a binary search insert using ``bisect.insort()``
+                [(row.get_field(sort_key), row) for row in self._sorted],
-        for row in filter(
+                key=lambda item: item[0],
-            row_filter or self.row_filter,
+        ))
-                reversed(
+        if key_row_pairs:
-                    sorted(
+            sorted_keys, sorted_rows = zip(*key_row_pairs)
-                        pairs.values(),
+            sorted_keys, sorted_rows = list(sorted_keys), list(sorted_rows)
-                        key=lambda row: row._last_record[sort_key]
-                    )
-                )
-        ):
-            widget = row.widget
-            if widget not in self._rendered:
-                self.add_widget(widget)  # row append
-                self._rendered.add(widget)
         else:
-                log.debug(f"Skipping adding widget {widget}")
+            sorted_keys, sorted_rows = [], []
+
+        # now remove and re-insert any rows that need to be shuffled
+        # due to new a new field change
+        for row in changed:
+            try:
+                old_index = sorted_rows.index(row)
+            except ValueError:
+                # row is not yet added so nothing to remove
+                pass
+            else:
+                del sorted_rows[old_index]
+                del sorted_keys[old_index]
+                self._sorted.remove(row)
+                self.remove_widget(row)
+
+        for row in changed:
+            key = row.get_field(sort_key)
+            index = bisect(sorted_keys, key)
+            sorted_keys.insert(index, key)
+            self._sorted.insert(index, row)
+            self.add_widget(row, index=index)
 
     def ticker_search(self, patt):
         """Return sequence of matches when pattern ``patt`` is in a
@@ -514,36 +536,41 @@ async def update_quotes(
         # revert flash state momentarily
         nursery.start_soon(revert_cells_color, unflash)
 
-    cache = {}
-    table.quote_cache = cache
-
     # initial coloring
+    to_sort = set()
     for sym, quote in first_quotes.items():
         row = table.get_row(sym)
         record, displayable = formatter(
             quote, symbol_data=symbol_data)
         row.update(record, displayable)
         color_row(row, record, {})
-        cache[sym] = row
+        to_sort.add(row.widget)
+
+    table.render_rows(to_sort)
 
     log.debug("Finished initializing update loop")
     task_status.started()
     # real-time cell update loop
     async for quotes in agen:  # new quotes data only
+        to_sort = set()
         for symbol, quote in quotes.items():
             record, displayable = formatter(
                 quote, symbol_data=symbol_data)
             row = table.get_row(symbol)
             cells = row.update(record, displayable)
             color_row(row, record, cells)
-            cache[symbol] = row
 
-        table.render_rows(cache)
+            if table.sort_key in record:
+                to_sort.add(row.widget)
+
+        if to_sort:
+            table.render_rows(to_sort)
+
         log.debug("Waiting on quotes")
 
     log.warn("Data feed connection dropped")
     # XXX: if we're cancelled this should never get called
-    nursery.cancel_scope.cancel()
+    # nursery.cancel_scope.cancel()
 
 
 async def _async_main(
@@ -638,6 +665,7 @@ async def _async_main(
     # set up a pager view for large ticker lists
     table.bind(minimum_height=table.setter('height'))
 
+    try:
         async with trio.open_nursery() as nursery:
             pager = PagerView(
                 container=box,
@@ -663,11 +691,11 @@ async def _async_main(
                 quotes
             )
 
-        try:
             # Trio-kivy entry point.
             await async_runTouchApp(widgets['root'])  # run kivy
-        finally:
-            # cancel aysnc gen call
-            await quote_gen.aclose()
             # cancel GUI update task
             nursery.cancel_scope.cancel()
+    finally:
+        with trio.open_cancel_scope(shield=True):
+            # cancel aysnc gen call
+            await quote_gen.aclose()