qt: defer hidden UTXO list model rebuilds

Author: rafael81

electrum/gui/qt/utxo_list.py

@@ -101,10 +101,16 @@ def cb():
     @profiler(min_threshold=0.05)
     def update(self):
         # not calling maybe_defer_update() as it interferes with coincontrol status bar
-        self.proxy.setDynamicSortFilter(False)  # temp. disable re-sorting after every change
         utxos = self.wallet.get_utxos()
         self._maybe_reset_coincontrol(utxos)
         self._utxo_dict = dict([(utxo.prevout.to_str(), utxo) for utxo in utxos])
+        if self.maybe_defer_update():
+            self.update_coincontrol_bar()
+            self.num_coins_label.setText(
+                _('{} unspent transaction outputs').format(len(utxos))
+            )
+            return
+        self.proxy.setDynamicSortFilter(False)  # temp. disable re-sorting after every change
         self.std_model.clear()
         self.update_headers(self.__class__.headers)
         for idx, utxo in enumerate(utxos):

tests/gui/__init__.py

@@ -0,0 +1 @@
+

tests/gui/test_qt_utxo_list.py

@@ -0,0 +1,130 @@
+import importlib.util
+import os
+import subprocess
+import sys
+import textwrap
+import unittest
+
+
+class TestUTXOList(unittest.TestCase):
+    def test_hidden_update_defers_expensive_model_rebuild(self):
+        if importlib.util.find_spec("PyQt6") is None:
+            self.skipTest("PyQt6 not available")
+
+        env = os.environ.copy()
+        env.setdefault("QT_QPA_PLATFORM", "offscreen")
+        script = textwrap.dedent(
+            r"""
+            from PyQt6.QtWidgets import QApplication, QLabel, QWidget
+
+            from electrum.simple_config import SimpleConfig
+            from electrum.gui.qt.utxo_list import UTXOList
+
+
+            class _Prevout:
+                def __init__(self, n):
+                    self.txid = bytes([n % 256]) * 32
+                    self.n = n
+
+                def to_str(self):
+                    return f"{self.txid.hex()}:{self.n}"
+
+
+            class _Utxo:
+                def __init__(self, n):
+                    self.prevout = _Prevout(n)
+                    self.short_id = f"{n}:0"
+                    self.address = f"addr{n}"
+                    self.block_height = n
+
+                def value_sats(self):
+                    return 1000
+
+
+            class _AddressDB:
+                def tx_height_to_sort_height(self, height):
+                    return height
+
+
+            class _Wallet:
+                def __init__(self, utxo_count):
+                    self.adb = _AddressDB()
+                    self._utxos = [_Utxo(n) for n in range(utxo_count)]
+
+                def get_utxos(self):
+                    return self._utxos
+
+                def get_num_parents(self, txid):
+                    return 0
+
+                def get_label_for_txid(self, txid):
+                    return ""
+
+                def is_frozen_address(self, address):
+                    return False
+
+                def is_frozen_coin(self, utxo):
+                    return False
+
+
+            class _MainWindow(QWidget):
+                def __init__(self, utxo_count):
+                    super().__init__()
+                    self.config = SimpleConfig({"electrum_path": "/tmp/electrum-test"})
+                    self.wallet = _Wallet(utxo_count)
+                    self.coincontrol_msg = None
+
+                def format_amount(self, amount, **kwargs):
+                    return str(amount)
+
+                def format_amount_and_units(self, amount):
+                    return str(amount)
+
+                def set_coincontrol_msg(self, msg):
+                    self.coincontrol_msg = msg
+
+
+            app = QApplication([])
+            window = _MainWindow(100)
+            utxo_list = UTXOList(window)
+            utxo_list.num_coins_label = QLabel()
+
+            utxo_list._forced_update = True
+            utxo_list.update()
+            utxo_list._forced_update = False
+            first_item = utxo_list.std_model.item(0, UTXOList.Columns.OUTPOINT)
+            assert utxo_list.std_model.rowCount() == 100
+
+            utxo_list.update()
+
+            assert first_item is utxo_list.std_model.item(0, UTXOList.Columns.OUTPOINT)
+            assert utxo_list._pending_update
+            assert len(utxo_list._utxo_dict) == 100
+            assert utxo_list.num_coins_label.text() == "100 unspent transaction outputs"
+
+            window.wallet._utxos = [_Utxo(n) for n in range(50)]
+            utxo_list.update()
+            assert utxo_list.std_model.rowCount() == 100
+            assert len(utxo_list._utxo_dict) == 50
+            assert utxo_list.num_coins_label.text() == "50 unspent transaction outputs"
+
+            utxo_list._forced_update = True
+            utxo_list.update()
+            utxo_list._forced_update = False
+            assert utxo_list.std_model.rowCount() == 50
+            app.quit()
+            """
+        )
+
+        result = subprocess.run(
+            [sys.executable, "-c", script],
+            env=env,
+            text=True,
+            capture_output=True,
+            timeout=30,
+        )
+        self.assertEqual(
+            0,
+            result.returncode,
+            f"stdout:\n{result.stdout}\nstderr:\n{result.stderr}",
+        )