qt history: speed up ensure_fields_available (faster startup)

electrum/gui/qt/history_list.py

@@ -31,7 +31,7 @@ from collections import OrderedDict
 
 from electrum.address_synchronizer import TX_HEIGHT_LOCAL
 from electrum.i18n import _
-from electrum.util import block_explorer_URL, profiler, print_error, TxMinedStatus, Fiat
+from electrum.util import block_explorer_URL, profiler, print_error, TxMinedStatus, OrderedDictWithIndex
 
 from .util import *
 
@@ -92,7 +92,7 @@ class HistoryList(MyTreeView, AcceptFileDragDrop):
         self.setModel(self.proxy)
 
         self.txid_to_items = {}
-        self.transactions = OrderedDict()
+        self.transactions = OrderedDictWithIndex()
         self.summary = {}
         self.blue_brush = QBrush(QColor("#1E1EFF"))
         self.red_brush = QBrush(QColor("#BC1E1E"))
@@ -311,7 +311,7 @@ class HistoryList(MyTreeView, AcceptFileDragDrop):
 
     def ensure_fields_available(self, items, idx, txid):
         while len(items) < idx + 1:
-            row = list(self.transactions.keys()).index(txid)
+            row = self.transactions.get_pos_of_key(txid)
             qidx = self.std_model.index(row, len(items))
             assert qidx.isValid(), (self.std_model.columnCount(), idx)
             item = self.std_model.itemFromIndex(qidx)
@@ -334,7 +334,6 @@ class HistoryList(MyTreeView, AcceptFileDragDrop):
             txid = row['txid']
             if txid not in self.transactions:
                 self.transactions[txid] = row
-                self.transactions.move_to_end(txid, last=True)
                 self.insert_tx(row)
                 return
             else:
@@ -344,7 +343,6 @@ class HistoryList(MyTreeView, AcceptFileDragDrop):
             seen.add(txid)
             if txid not in self.transactions:
                 self.transactions[txid] = row
-                self.transactions.move_to_end(txid, last=True)
                 self.insert_tx(row)
                 continue
             old = self.transactions[txid]

electrum/util.py

@@ -22,7 +22,7 @@
 # SOFTWARE.
 import binascii
 import os, sys, re, json
-from collections import defaultdict
+from collections import defaultdict, OrderedDict
 from typing import NamedTuple, Union, TYPE_CHECKING, Tuple, Optional, Callable
 from datetime import datetime
 import decimal
@@ -993,3 +993,55 @@ def create_and_start_event_loop() -> Tuple[asyncio.AbstractEventLoop,
                                          name='EventLoop')
     loop_thread.start()
     return loop, stopping_fut, loop_thread
+
+
+class OrderedDictWithIndex(OrderedDict):
+    """An OrderedDict that keeps track of the positions of keys.
+
+    Note: very inefficient to modify contents, except to add new items.
+    """
+
+    _key_to_pos = {}
+
+    def _recalc_key_to_pos(self):
+        self._key_to_pos = {key: pos for (pos, key) in enumerate(self.keys())}
+
+    def get_pos_of_key(self, key):
+        return self._key_to_pos[key]
+
+    def popitem(self, *args, **kwargs):
+        ret = super().popitem(*args, **kwargs)
+        self._recalc_key_to_pos()
+        return ret
+
+    def move_to_end(self, *args, **kwargs):
+        ret = super().move_to_end(*args, **kwargs)
+        self._recalc_key_to_pos()
+        return ret
+
+    def clear(self):
+        ret = super().clear()
+        self._recalc_key_to_pos()
+        return ret
+
+    def pop(self, *args, **kwargs):
+        ret = super().pop(*args, **kwargs)
+        self._recalc_key_to_pos()
+        return ret
+
+    def update(self, *args, **kwargs):
+        ret = super().update(*args, **kwargs)
+        self._recalc_key_to_pos()
+        return ret
+
+    def __delitem__(self, *args, **kwargs):
+        ret = super().__delitem__(*args, **kwargs)
+        self._recalc_key_to_pos()
+        return ret
+
+    def __setitem__(self, key, *args, **kwargs):
+        is_new_key = key not in self
+        ret = super().__setitem__(key, *args, **kwargs)
+        if is_new_key:
+            self._key_to_pos[key] = len(self) - 1
+        return ret