From 758550ea1774ee4e543f7133d4f1b4956e7ba550 Mon Sep 17 00:00:00 2001
From: Damien Elmes <gpg@ankiweb.net>
Date: Mon, 5 Apr 2021 14:42:04 +1000
Subject: [PATCH] fix row cache issues

I think this may have accidentally been changed in the refactoring.
If we discard self._rows, it will result in the entire table flashing
"..." until the new data is available. Instead, we leave the cached
rows alone, and just update the cutoff point, so we can serve stale
content (avoiding any visible redraw) until the new data is available.

I've updated search() to reset the rows there, so we free up memory
on a new search.
---
 qt/aqt/table.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/qt/aqt/table.py b/qt/aqt/table.py
index 3fab969c2..db10e19a0 100644
--- a/qt/aqt/table.py
+++ b/qt/aqt/table.py
@@ -182,7 +182,7 @@ class Table:
 
     def op_executed(self, changes: OpChanges, meta: OpMeta, focused: bool) -> None:
         if changes.browser_table:
-            self._model.empty_cache()
+            self._model.mark_cache_stale()
         if focused:
             self.redraw_cells()
 
@@ -858,9 +858,9 @@ class DataModel(QAbstractTableModel):
         self._state: ItemState = state
         self._items: Sequence[ItemId] = []
         self._rows: Dict[int, CellRow] = {}
-        self._last_refresh = 0.0
         # serve stale content to avoid hitting the DB?
         self._block_updates = False
+        self._stale_cutoff = 0.0
 
     # Row Object Interface
     ######################################################################
@@ -873,7 +873,7 @@ class DataModel(QAbstractTableModel):
     def get_row(self, index: QModelIndex) -> CellRow:
         item = self.get_item(index)
         if row := self._rows.get(item):
-            if not self._block_updates and row.is_stale(self._last_refresh):
+            if not self._block_updates and row.is_stale(self._stale_cutoff):
                 # need to refresh
                 self._rows[item] = self._fetch_row_from_backend(item)
                 return self._rows[item]
@@ -901,8 +901,8 @@ class DataModel(QAbstractTableModel):
 
     # Reset
 
-    def empty_cache(self) -> None:
-        self._rows = {}
+    def mark_cache_stale(self) -> None:
+        self._stale_cutoff = time.time()
 
     def reset(self) -> None:
         self.begin_reset()
@@ -910,7 +910,7 @@ class DataModel(QAbstractTableModel):
 
     def begin_reset(self) -> None:
         self.beginResetModel()
-        self.empty_cache()
+        self.mark_cache_stale()
 
     def end_reset(self) -> None:
         self.endResetModel()
@@ -930,7 +930,6 @@ class DataModel(QAbstractTableModel):
             return
         top_left = self.index(0, 0)
         bottom_right = self.index(self.len_rows() - 1, self.len_columns() - 1)
-        self._last_refresh = time.time()
         self.dataChanged.emit(top_left, bottom_right)  # type: ignore
 
     # Item Interface
@@ -1014,6 +1013,7 @@ class DataModel(QAbstractTableModel):
                 context.ids = self._state.find_items(context.search, context.order)
             gui_hooks.browser_did_search(context)
             self._items = context.ids
+            self._rows = {}
         finally:
             self.end_reset()