From 6f52a7c870f011f1382e01df2326f233c7fc2a3a Mon Sep 17 00:00:00 2001
From: "James E. Blair" <jeblair@hp.com>
Date: Tue, 2 Sep 2014 16:52:55 -0700
Subject: [PATCH] Don't modify status widgets outside of main thread

The sync module would indirectly modify the status widget (so that
the count of sync actions would be up to date).  If this happened
while urwid was drawing the screen, urwid may invalidate cached
information in mid-redraw, resulting in an exception and crash.
This updates the StatusHeader widget so that changes are merely
recorded to internal variables, and the actual widgets are updated
by a refresh method called from within the main loop.

Change-Id: I27043533d33d44aae31005670a1b727e9cc7bb90
Story: 260
---
 gertty/app.py  | 63 ++++++++++++++++++++++++++++++++++++--------------
 gertty/sync.py |  6 ++---
 2 files changed, 49 insertions(+), 20 deletions(-)

diff --git a/gertty/app.py b/gertty/app.py
index 300e53c..a3a7e3e 100644
--- a/gertty/app.py
+++ b/gertty/app.py
@@ -53,27 +53,55 @@ class StatusHeader(urwid.WidgetWrap):
     def __init__(self, app):
         super(StatusHeader, self).__init__(urwid.Columns([]))
         self.app = app
-        self.title = urwid.Text(u'Start')
-        self.error = urwid.Text('')
-        self.offline = urwid.Text('')
-        self.sync = urwid.Text(u'Sync: 0')
-        self._w.contents.append((self.title, ('pack', None, False)))
+        self.title_widget = urwid.Text(u'Start')
+        self.error_widget = urwid.Text('')
+        self.offline_widget = urwid.Text('')
+        self.sync_widget = urwid.Text(u'Sync: 0')
+        self._w.contents.append((self.title_widget, ('pack', None, False)))
         self._w.contents.append((urwid.Text(u''), ('weight', 1, False)))
-        self._w.contents.append((self.error, ('pack', None, False)))
-        self._w.contents.append((self.offline, ('pack', None, False)))
-        self._w.contents.append((self.sync, ('pack', None, False)))
+        self._w.contents.append((self.error_widget, ('pack', None, False)))
+        self._w.contents.append((self.offline_widget, ('pack', None, False)))
+        self._w.contents.append((self.sync_widget, ('pack', None, False)))
+        self.error = None
+        self.offline = None
+        self.title = None
+        self.sync = None
+        self._error = False
+        self._offline = False
+        self._title = ''
+        self._sync = 0
 
-    def update(self, title=None, error=False, offline=None):
-        if title:
-            self.title.set_text(title)
-        if error:
-            self.error.set_text(('error', u'Error'))
+    def update(self, title=None, error=None, offline=None, refresh=True):
+        if title is not None:
+            self.title = title
+        if error is not None:
+            self.error = error
         if offline is not None:
-            if offline:
-                self.error.set_text(u'Offline')
+            self.offline = offline
+        self.sync = self.app.sync.queue.qsize()
+        if refresh:
+            self.refresh()
+
+    def refresh(self):
+        if self._title != self.title:
+            self._title = self.title
+            self.title_widget.set_text(self._title)
+        if self._error != self.error:
+            self._error = self.error
+            if self.error:
+                self.error_widget.set_text(('error', u'Error'))
             else:
-                self.error.set_text(u'')
-        self.sync.set_text(u' Sync: %i' % self.app.sync.queue.qsize())
+                self.error_widget.set_text(u'')
+        if self._offline != self.offline:
+            self._offline = self.offline
+            if self._offline:
+                self.offline_widget.set_text(u'Offline')
+            else:
+                self.offline_widget.set_text(u'')
+        if self._sync != self.sync:
+            self._sync = self.sync
+            self.sync_widget.set_text(u' Sync: %i' % self._sync)
+
 
 class SearchDialog(mywid.ButtonDialog):
     signals = ['search', 'cancel']
@@ -194,6 +222,7 @@ class App(object):
             self.loop.widget = widget
 
     def refresh(self, data=None):
+        self.status.refresh()
         widget = self.loop.widget
         while isinstance(widget, urwid.Overlay):
             widget = widget.contents[0][0]
diff --git a/gertty/sync.py b/gertty/sync.py
index 9c93aeb..1b23593 100644
--- a/gertty/sync.py
+++ b/gertty/sync.py
@@ -790,16 +790,16 @@ class Sync(object):
                 self.submitTask(SyncSubscribedProjectsTask(HIGH_PRIORITY))
                 self.submitTask(UploadReviewsTask(HIGH_PRIORITY))
             self.offline = True
-            self.app.status.update(offline=True)
+            self.app.status.update(offline=True, refresh=False)
             os.write(pipe, 'refresh\n')
             time.sleep(30)
             return task
         except Exception:
             task.complete(False)
             self.log.exception('Exception running task %s' % (task,))
-            self.app.status.update(error=True)
+            self.app.status.update(error=True, refresh=False)
         self.offline = False
-        self.app.status.update(offline=False)
+        self.app.status.update(offline=False, refresh=False)
         os.write(pipe, 'refresh\n')
         return None