address_sync: change up_to_date to be private; no lock needed to read

After some consideration I am fairly certain there is no need to take
wallet.lock in `is_up_to_date()`. Any caller that might want some kind
of guarantees re the value returned by is_up_to_date() would need to
enforce them itself by e.g. taking wallet.lock around its critical code
block. That is, even if is_up_to_date() itself takes the lock, between
the call returning and the caller reading the value there could still
have been a race.
Also, the GUI was directly accessing the field already.

electrum/address_synchronizer.py

@@ -88,7 +88,7 @@ class AddressSynchronizer(Logger):
         # Transactions pending verification.  txid -> tx_height. Access with self.lock.
         self.unverified_tx = defaultdict(int)
         # true when synchronized
-        self.up_to_date = False
+        self._up_to_date = False
         # thread local storage for caching stuff
         self.threadlocal_cache = threading.local()
 
@@ -650,15 +650,15 @@ class AddressSynchronizer(Logger):
 
     def set_up_to_date(self, up_to_date):
         with self.lock:
-            status_changed = self.up_to_date != up_to_date
-            self.up_to_date = up_to_date
+            status_changed = self._up_to_date != up_to_date
+            self._up_to_date = up_to_date
         if self.network:
             self.network.notify('status')
         if status_changed:
             self.logger.info(f'set_up_to_date: {up_to_date}')
 
     def is_up_to_date(self):
-        with self.lock: return self.up_to_date
+        return self._up_to_date
 
     def get_history_sync_state_details(self) -> Tuple[int, int]:
         if self.synchronizer:

electrum/gui/kivy/main_window.py

@@ -927,7 +927,7 @@ class ElectrumWindow(App, Logger):
             self.num_blocks = self.network.get_local_height()
             server_height = self.network.get_server_height()
             server_lag = self.num_blocks - server_height
-            if not self.wallet.up_to_date or server_height == 0:
+            if not self.wallet.is_up_to_date() or server_height == 0:
                 num_sent, num_answered = self.wallet.get_history_sync_state_details()
                 status = ("{} [size=18dp]({}/{})[/size]"
                           .format(_("Synchronizing..."), num_answered, num_sent))
@@ -951,7 +951,7 @@ class ElectrumWindow(App, Logger):
     def update_wallet_synchronizing_progress(self, *dt):
         if not self.wallet:
             return
-        if not self.wallet.up_to_date:
+        if not self.wallet.is_up_to_date():
             self._trigger_update_status()
 
     def get_max_amount(self):
@@ -1010,7 +1010,7 @@ class ElectrumWindow(App, Logger):
     #@profiler
     def update_wallet(self, *dt):
         self._trigger_update_status()
-        if self.wallet and (self.wallet.up_to_date or not self.network or not self.network.is_connected()):
+        if self.wallet and (self.wallet.is_up_to_date() or not self.network or not self.network.is_connected()):
             self.update_tabs()
 
     def notify(self, message):

electrum/gui/qt/main_window.py

@@ -836,7 +836,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
     def notify_transactions(self):
         if self.tx_notification_queue.qsize() == 0:
             return
-        if not self.wallet.up_to_date:
+        if not self.wallet.is_up_to_date():
             return  # no notifications while syncing
         now = time.time()
         rate_limit = 20  # seconds
@@ -883,7 +883,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         if self.need_update.is_set():
             self.need_update.clear()
             self.update_wallet()
-        elif not self.wallet.up_to_date:
+        elif not self.wallet.is_up_to_date():
             # this updates "synchronizing" progress
             self.update_status()
         # resolve aliases
@@ -977,7 +977,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
             # Server height can be 0 after switching to a new server
             # until we get a headers subscription request response.
             # Display the synchronizing message in that case.
-            if not self.wallet.up_to_date or server_height == 0:
+            if not self.wallet.is_up_to_date() or server_height == 0:
                 num_sent, num_answered = self.wallet.get_history_sync_state_details()
                 network_text = ("{} ({}/{})"
                                 .format(_("Synchronizing..."), num_answered, num_sent))
@@ -1022,7 +1022,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
 
     def update_wallet(self):
         self.update_status()
-        if self.wallet.up_to_date or not self.network or not self.network.is_connected():
+        if self.wallet.is_up_to_date() or not self.network or not self.network.is_connected():
             self.update_tabs()
 
     def update_tabs(self, wallet=None):

electrum/gui/stdio.py

@@ -118,7 +118,7 @@ class ElectrumGui(BaseElectrumGui):
 
     def get_balance(self):
         if self.wallet.network.is_connected():
-            if not self.wallet.up_to_date:
+            if not self.wallet.is_up_to_date():
                 msg = _("Synchronizing...")
             else:
                 c, u, x =  self.wallet.get_balance()

electrum/gui/text.py

@@ -148,7 +148,7 @@ class ElectrumGui(BaseElectrumGui):
         if not self.network:
             msg = _("Offline")
         elif self.network.is_connected():
-            if not self.wallet.up_to_date:
+            if not self.wallet.is_up_to_date():
                 msg = _("Synchronizing...")
             else:
                 c, u, x =  self.wallet.get_balance()