Add model batch removal optimization for filtering

src/backend/models/filters.py

@@ -58,7 +58,7 @@ class ModelFilter(ModelProxy):
         take_out   = []
         bring_back = []
 
-        for key, item in self.items():
+        for key, item in sorted(self.items(), key=lambda kv: kv[1]):
             if not self.accept_item(item):
                 take_out.append(key)
 
@@ -66,8 +66,9 @@ class ModelFilter(ModelProxy):
             if self.accept_item(item):
                 bring_back.append(key)
 
-        for key in take_out:
-            self.filtered_out[key] = self.pop(key)
+        with self.batch_remove():
+            for key in take_out:
+                self.filtered_out[key] = self.pop(key)
 
         for key in bring_back:
             self[key] = self.filtered_out.pop(key)

src/backend/models/model.py

@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 
+import itertools
 from bisect import bisect
+from contextlib import contextmanager
 from threading import RLock
 from typing import (
     TYPE_CHECKING, Any, Dict, Iterator, List, MutableMapping, Optional,
@@ -42,6 +44,8 @@ class Model(MutableMapping):
 
         self.take_items_ownership: bool = True
 
+        self._active_batch_remove_indice: Optional[List[int]] = None
+
         if self.sync_id:
             self.instances[self.sync_id] = self
 
@@ -144,7 +148,10 @@ class Model(MutableMapping):
                     proxy.source_item_deleted(self, key)
 
             if self.sync_id:
-                ModelItemDeleted(self.sync_id, index)
+                if self._active_batch_remove_indice is None:
+                    ModelItemDeleted(self.sync_id, index)
+                else:
+                    self._active_batch_remove_indice.append(index)
 
 
     def __iter__(self) -> Iterator:
@@ -170,3 +177,18 @@ class Model(MutableMapping):
         new = type(self)(sync_id=sync_id)
         new.update(self)
         return new
+
+
+    @contextmanager
+    def batch_remove(self):
+        try:
+            self._active_batch_remove_indice = []
+            yield None
+        finally:
+            indice = self._active_batch_remove_indice
+            groups = [list(group) for item, group in itertools.groupby(indice)]
+
+            for grp in groups:
+                ModelItemDeleted(self.sync_id, index=grp[0], count=len(grp))
+
+            self._active_batch_remove_indice = None

src/backend/models/proxy.py

@@ -43,6 +43,7 @@ class ModelProxy(Model):
 
     def source_cleared(self, source: Model) -> None:
         if self.accept_source(source):
-            for source_sync_id, key in self.copy():
-                if source_sync_id == source.sync_id:
-                    del self[source_sync_id, key]
+            with self.batch_remove():
+                for source_sync_id, key in self.copy():
+                    if source_sync_id == source.sync_id:
+                        del self[source_sync_id, key]

src/backend/pyotherside_events.py

@@ -82,6 +82,7 @@ class ModelItemDeleted(ModelEvent):
     """Indicate the removal of a `ModelItem` from a `Backend` `Model`."""
 
     index: int = field()
+    count: int = 1
 
 
 @dataclass