Keep a {id: item} cache for ModelStore models

Accelerates the ModelStore ListView find() function,
which now just has to get an object key instead of looping through the
whole model.

src/backend/models/model.py

@@ -44,7 +44,8 @@ class Model(MutableMapping):
 
         self.take_items_ownership: bool = True
 
-        self._active_batch_remove_indice: Optional[List[int]] = None
+        # [(index, item.id), ...]
+        self._active_batch_removed: Optional[List[Tuple[int, Any]]] = None
 
         if self.sync_id:
             self.instances[self.sync_id] = self
@@ -148,10 +149,10 @@ class Model(MutableMapping):
                     proxy.source_item_deleted(self, key)
 
             if self.sync_id:
-                if self._active_batch_remove_indice is None:
-                    ModelItemDeleted(self.sync_id, index)
+                if self._active_batch_removed is None:
+                    ModelItemDeleted(self.sync_id, index, 1, (item.id,))
                 else:
-                    self._active_batch_remove_indice.append(index)
+                    self._active_batch_removed.append((index, item.id))
 
 
     def __iter__(self) -> Iterator:
@@ -189,17 +190,21 @@ class Model(MutableMapping):
 
         with self.write_lock:
             try:
-                self._active_batch_remove_indice = []
+                self._active_batch_removed = []
                 yield None
             finally:
-                indice = self._active_batch_remove_indice
+                batch  = self._active_batch_removed
                 groups = [
-                    list(group) for item, group in itertools.groupby(indice)
+                    list(group) for item, group in
+                    itertools.groupby(batch, key=lambda x: x[0])
                 ]
 
-                for grp in groups:
+                for group in groups:
                     ModelItemDeleted(
-                        self.sync_id, index=grp[0], count=len(grp),
+                        self.sync_id,
+                        index = group[0][0],
+                        count = len(group),
+                        ids   = [item[1] for item in group],
                     )
 
-                self._active_batch_remove_indice = None
+                self._active_batch_removed = None

src/backend/pyotherside_events.py

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 
 from dataclasses import dataclass, field
-from typing import TYPE_CHECKING, Any, Dict, Optional
+from typing import TYPE_CHECKING, Any, Dict, Optional, Sequence
 
 import pyotherside
 
@@ -83,8 +83,9 @@ class ModelItemSet(ModelEvent):
 class ModelItemDeleted(ModelEvent):
     """Indicate the removal of a `ModelItem` from a `Backend` `Model`."""
 
-    index: int = field()
-    count: int = 1
+    index: int           = field()
+    count: int           = 1
+    ids:   Sequence[Any] = ()
 
 
 @dataclass

src/gui/ModelStore.qml

@@ -13,6 +13,7 @@ QtObject {
         readonly property Component model: Component {
             ListModel {
                 property var modelId
+                property var idToItems: ({})
 
                 // Used by HFilterModel
                 signal fieldsChanged(int index, var changes)
@@ -25,10 +26,7 @@ QtObject {
                 }
 
                 function find(id, default_=null) {
-                    for (let i = 0; i < count; i++)
-                        if (get(i).id === id) return get(i)
-
-                    return default_
+                    return idToItems[id] || default_
                 }
             }
         }

src/gui/Pages/Chat/Chat.qml

@@ -12,8 +12,8 @@ Item {
     property string userId
     property string roomId
 
-    property QtObject userInfo: null
-    property QtObject roomInfo: null
+    property QtObject userInfo: ModelStore.get("accounts").find(userId)
+    property QtObject roomInfo: ModelStore.get(userId, "rooms").find(roomId)
 
     property bool ready: Boolean(userInfo && roomInfo)
     property bool longLoading: false
@@ -58,22 +58,6 @@ Item {
         )
     }
 
-    Timer {
-        interval: 100
-        running: ! userInfo
-        repeat: true
-        triggeredOnStart: true
-        onTriggered: userInfo = ModelStore.get("accounts").find(userId)
-    }
-
-    Timer {
-        interval: 100
-        running: ! roomInfo
-        repeat: true
-        triggeredOnStart: true
-        onTriggered: roomInfo = ModelStore.get(userId, "rooms").find(roomId)
-    }
-
     Timer {
         interval: 300
         running: ! ready

src/gui/PythonBridge/EventHandlers.qml

@@ -51,16 +51,19 @@ QtObject {
         py.showError(type, traceback, message)
     }
 
-    function onModelItemSet(syncId, indexThen, indexNow, changedFields){
+    function onModelItemSet(syncId, indexThen, indexNow, changedFields) {
+        const model = ModelStore.get(syncId)
+
         if (indexThen === undefined) {
             // print("insert", syncId, indexThen, indexNow,
                   // JSON.stringify(changedFields))
-            ModelStore.get(syncId).insert(indexNow, changedFields)
+            model.insert(indexNow, changedFields)
+            model.idToItems[changedFields.id] = model.get(indexNow)
+            model.idToItemsChanged()
 
         } else {
             // print("set", syncId, indexThen, indexNow,
                   // JSON.stringify(changedFields))
-            const model = ModelStore.get(syncId)
             model.set(indexThen, changedFields)
 
             if (indexThen !== indexNow) model.move(indexThen, indexNow, 1)
@@ -69,14 +72,22 @@ QtObject {
         }
     }
 
-    function onModelItemDeleted(syncId, index, count=1) {
-        // print("delete", syncId, index, count)
-        ModelStore.get(syncId).remove(index, count)
+    function onModelItemDeleted(syncId, index, count=1, ids=[]) {
+        // print("delete", syncId, index, count, ids)
+        const model = ModelStore.get(syncId)
+        model.remove(index, count)
+
+        for (let i = 0; i < ids.length; i++) {
+            delete model.idToItems[ids[i]]
+        }
+
+        if (ids.length) model.idToItemsChanged()
     }
 
     function onModelCleared(syncId) {
         // print("clear", syncId)
         ModelStore.get(syncId).clear()
+        model.idToItems = {}
     }
 
     function onDevicesUpdated(forAccount) {