wallet.get_tx_parents: populate cache regardless of self.is_up_to_date()

Fixes #8315

electrum/gui/qt/utxo_list.py

@@ -134,8 +134,8 @@ class UTXOList(MyTreeView):
         utxo = self._utxo_dict[key]
         utxo_item = [self.std_model.item(row, col) for col in self.Columns]
         txid = utxo.prevout.txid.hex()
-        parents = self.wallet.get_tx_parents(txid)
-        utxo_item[self.Columns.PARENTS].setText('%6s'%len(parents))
+        num_parents = self.wallet.get_num_parents(txid)
+        utxo_item[self.Columns.PARENTS].setText('%6s'%num_parents if num_parents else '-')
         label = self.wallet.get_label_for_txid(txid) or ''
         utxo_item[self.Columns.LABEL].setText(label)
         SELECTED_TO_SPEND_TOOLTIP = _('Coin selected to be spent')

electrum/wallet.py

@@ -884,17 +884,20 @@ class Abstract_Wallet(ABC, Logger, EventListener):
             is_related_to_wallet=is_relevant,
         )
 
+    def get_num_parents(self, txid: str) -> Optional[int]:
+        if not self.is_up_to_date():
+            return
+        return len(self.get_tx_parents(txid))
+
     def get_tx_parents(self, txid: str) -> Dict[str, Tuple[List[str], List[str]]]:
         """
-        recursively calls itself and returns a flat dict:
+        returns a flat dict:
         txid -> list of parent txids
         """
-        if not self.is_up_to_date():
-            return {}
         with self.lock, self.transaction_lock:
             if self._last_full_history is None:
                 self._last_full_history = self.get_full_history(None, include_lightning=False)
-                # populate cache in chronological order to avoid recursion limit
+                # populate cache in chronological order
                 for _txid in self._last_full_history.keys():
                     self.get_tx_parents(_txid)
 
@@ -924,7 +927,8 @@ class Abstract_Wallet(ABC, Logger, EventListener):
 
             for _txid in parents + uncles:
                 if _txid in self._last_full_history.keys():
-                    result.update(self.get_tx_parents(_txid))
+                    p = self._tx_parents_cache[_txid]
+                    result.update(p)
             result[txid] = parents, uncles
             self._tx_parents_cache[txid] = result
             return result