Added watchdog for hanging apps

config.py

@@ -6,6 +6,9 @@ ScreenY = 40
 
 Serial = "/dev/ttyACM0"
 
+# kills app after some seconds if it sends no data
+NoDataTimeout = 10
+
 # first app is always running in IDLE    
 Apps = [
     {"name": "pixelflut", "cmd": "apps/idle.py", "permanent": True},

main.py

@@ -16,7 +16,6 @@ class SerialWriter(threading.Thread):
     def setData(self, data):
         with self.lock:
             self.data = data
-        pass
     
     def run(self):
         should_connect = True
@@ -38,6 +37,16 @@ class SerialWriter(threading.Thread):
                 time.sleep(0.1)
 
 
+class WatchDog(threading.Thread):
+    def __init__(self, check, action):
+        super().__init__()
+        self.check = check
+        self.action = action
+    def run(self):
+        while True:
+            if self.check():
+                self.action()
+            time.sleep(1)
 
 
 class AppRunner(threading.Thread):
@@ -50,17 +59,32 @@ class AppRunner(threading.Thread):
         self.param = ""
         self.serial = SerialWriter()
         self.serial.start()
+        self.last_update = time.time()
+        self.watchdog = WatchDog(lambda: self.appTimedOut(), lambda: self.terminateApp())
+        self.watchdog.start()
 
     def requestApp(self, app, param=""):
         with self.lock:
             self.requestedApp = app
             self.param = param
 
+    def terminateApp(self):
+        if self.app != None:
+            # don't ask
+            self.app.terminate()
+            self.app.kill()
+            self.app.stdout.close()
+            self.last_update = time.time()
+        self.requestApp = 0
+
+    def appTimedOut(self):
+        return time.time()-self.last_update > config.NoDataTimeout
+
     def updateApp(self):
         if self.app != None:
             self.app.terminate()
         args = [os.getcwd()+"/"+config.Apps[self.requestedApp]["cmd"], str(config.ScreenX), str(config.ScreenY), self.param]
-        self.app = subprocess.Popen(args, stdout=subprocess.PIPE)
+        self.app = subprocess.Popen(args, stdout=subprocess.PIPE, close_fds=True)
 
     def run(self):
         while True:
@@ -73,8 +97,12 @@ class AppRunner(threading.Thread):
                     self.requestedApp = None
             d = self.app.stdout
             oshandle = d.fileno()
+            try:
                 data = os.read(oshandle, config.ScreenX*config.ScreenY*3)
+                self.last_update = time.time()
                 self.serial.setData(data)
+            except:
+                pass
 
 
 runner = AppRunner()