Handles RPC failure in Qt with message box and quit.

jmclient/jmclient/wallet_service.py

@@ -79,6 +79,12 @@ class WalletService(Service):
         False, otherwise return True (means self.current_blockheight
         has been correctly updated).
         """
+
+        def critical_error():
+            jlog.error("Failure to get blockheight from Bitcoin Core.")
+            self.stopService()
+            return False
+
         if self.current_blockheight:
             old_blockheight = self.current_blockheight
         else:
@@ -88,13 +94,9 @@ class WalletService(Service):
         except Exception as e:
             # This should never happen now, as we are catching every
             # possible Exception in jsonrpc or bci.rpc:
-            jlog.error("Failure to get blockheight from Bitcoin Core:")
+            return critical_error()
-            jlog.error(repr(e))
-            if reactor.running:
-                reactor.stop()
-            return False
         if not self.current_blockheight:
-            return False
+            return critical_error()
 
         # We have received a new blockheight from Core, sanity check it:
         assert isinstance(self.current_blockheight, Integral)
@@ -191,7 +193,9 @@ class WalletService(Service):
         """
         if not syncresult:
             jlog.error("Failed to sync the bitcoin wallet. Shutting down.")
-            reactor.stop()
+            self.stopService()
+            if reactor.running:
+                reactor.stop()
             return
         jlog.info("Starting transaction monitor in walletservice")
         self.monitor_loop = task.LoopingCall(

scripts/joinmarket-qt.py

@@ -1403,7 +1403,8 @@ class JMMainWindow(QMainWindow):
             event.accept()
             if self.reactor.threadpool is not None:
                 self.reactor.threadpool.stop()
-            self.reactor.stop()
+            if reactor.running:
+                self.reactor.stop()
         else:
             event.ignore()
 
@@ -1765,10 +1766,25 @@ class JMMainWindow(QMainWindow):
         t = self.centralWidget().widget(0)
         if not self.wallet_service:  #failure to sync in constructor means object is not created
             newsyncmsg = "Unable to sync wallet - see error in console."
+        elif not self.wallet_service.isRunning():
+            JMQtMessageBox(self,
+                           "The Joinmarket wallet service has stopped; this is usually caused "
+                           "by a Bitcoin Core RPC connection failure. Is your node running?",
+                           mbtype='crit',
+                           title="Error")
+            qApp.exit(EXIT_FAILURE)
+            return
         elif not self.wallet_service.synced:
             return
         else:
-            t.updateWalletInfo(get_wallet_printout(self.wallet_service))
+            try:
+                t.updateWalletInfo(get_wallet_printout(self.wallet_service))
+            except Exception:
+                # this is very likely to happen in case Core RPC connection goes
+                # down (but, order of events means it is not deterministic).
+                log.debug("Failed to get wallet information, is there a problem with "
+                          "the blockchain interface?")
+                return
             newsyncmsg = "Wallet synced successfully."
         if newsyncmsg != self.syncmsg:
             self.syncmsg = newsyncmsg