Make separate tasks for collect vs. transmit of upgrade progress data

tailbone/templates/upgrades/view.mako

@@ -116,7 +116,9 @@
   <div class="form">
     <${form.component}
       % if expose_websockets and master.has_perm('execute'):
+      % if instance_executable:
       @execute-upgrade-click="executeUpgrade"
+      % endif
       :upgrade-executing="upgradeExecuting"
       @declare-failure-click="declareFailureClick"
       :declare-failure-submitting="declareFailureSubmitting"

tailbone/views/asgi/upgrades.py

@@ -40,6 +40,8 @@ class UpgradeExecutionProgressWS(WebsocketView):
         'upgrades': {},
     }
 
+    new_messages = asyncio.Queue()
+
     async def __call__(self, scope, receive, send):
         app = self.get_rattail_app()
 
@@ -116,10 +118,34 @@ class UpgradeExecutionProgressWS(WebsocketView):
         progress_session = get_basic_session(self.rattail_config,
                                              id=progress_session_id)
 
+        # start collecting status, textout messages
+        asyncio.create_task(self.collect_status(uuid, progress_session))
+        asyncio.create_task(self.collect_textout(uuid))
+
         upgrade_state = self.global_state['upgrades'][uuid]
         clients = upgrade_state['clients']
         while clients:
 
+            msg = await self.new_messages.get()
+
+            # send message to all clients
+            for client in clients.values():
+                await client['send']({
+                    'type': 'websocket.send',
+                    'subtype': 'upgrades.execute_progress',
+                    'text': json.dumps(msg)})
+
+            await asyncio.sleep(0.1)
+
+        # no more clients, no more reason to track this upgrade
+        del self.global_state['upgrades'][uuid]
+
+    async def collect_status(self, uuid, progress_session):
+
+        upgrade_state = self.global_state['upgrades'][uuid]
+        clients = upgrade_state['clients']
+        while True:
+
             # load latest progress data
             progress_session.load()
 
@@ -134,45 +160,58 @@ class UpgradeExecutionProgressWS(WebsocketView):
                         user_session.flash(msg)
                         user_session.persist()
 
-                # tell clients progress is complete
-                for client in clients.values():
-                    await client['send']({
-                        'type': 'websocket.send',
-                        'subtype': 'upgrades.execute_progress',
-                        'text': json.dumps({'complete': True})})
+                # push "complete" message to queue
+                await self.new_messages.put({'complete': True})
 
-                # this websocket is done, so remove all clients
-                clients.clear()
+                # there will be no more status coming
                 break
 
-            # we will send this data down to client
-            data = {}
+            await asyncio.sleep(0.1)
 
-            # maybe add more lines from command output
+    async def collect_textout(self, uuid):
         path = self.rattail_config.upgrade_filepath(uuid, filename='stdout.log')
-            offset = progress_session.get('stdout.offset', 0)
-            if os.path.exists(path):
+
+        # wait until stdout file exists
+        while not os.path.exists(path):
+
+            # bail if upgrade is complete
+            if uuid not in self.global_state['upgrades']:
+                return
+
+            await asyncio.sleep(0.1)
+
+        offset = 0
+        while True:
+
+            # wait until we have something new to read
             size = os.path.getsize(path) - offset
-                if size > 0:
+            while not size:
+
+                # bail if upgrade is complete
+                if uuid not in self.global_state['upgrades']:
+                    return
+
+                # wait a whole second, then look again
+                # (the less frequent we look, the bigger the chunk)
+                await asyncio.sleep(1)
+                size = os.path.getsize(path) - offset
+
+            # bail if upgrade is complete
+            if uuid not in self.global_state['upgrades']:
+                return
+
+            # read the latest chunk and bookmark new offset
             with open(path, 'rb') as f:
                 f.seek(offset)
                 chunk = f.read(size)
-                        data['stdout'] = chunk.decode('utf8').replace('\n', '<br />')
-                    progress_session['stdout.offset'] = offset + size
-                    progress_session.save()
+                textout = chunk.decode('utf_8')
+            offset += size
 
-            # send data to clients
-            for client in clients.values():
-                await client['send']({
-                    'type': 'websocket.send',
-                    'subtype': 'upgrades.execute_progress',
-                    'text': json.dumps(data)})
+            # push new chunk onto message queue
+            textout = textout.replace('\n', '<br />')
+            await self.new_messages.put({'stdout': textout})
 
-            # pause for 1 second
-            await asyncio.sleep(1)
-
-        # no more clients, no more reason to track this upgrade
-        del self.global_state['upgrades'][uuid]
+            await asyncio.sleep(0.1)
 
     @classmethod
     def defaults(cls, config):