serialhdl: Use reactor mutex in send_with_response()

Reduce the delay in send_with_response() by introducing a reactor
mutex to wake the main thread when the response is obtained.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/serialhdl.py

@@ -44,9 +44,9 @@ class SerialReader:
             params['#sent_time'] = response.sent_time
             params['#receive_time'] = response.receive_time
             hdl = (params['#name'], params.get('oid'))
+            try:
                 with self.lock:
                     hdl = self.handlers.get(hdl, self.handle_default)
-            try:
                     hdl(params)
             except:
                 logging.exception("Exception in serial callback")
@@ -197,28 +197,36 @@ class SerialRetryCommand:
         self.name = name
         self.oid = oid
         self.response = None
+        reactor = self.serial.reactor
+        self.mutex = reactor.mutex(is_locked=True)
         self.min_query_time = self.serial.reactor.monotonic()
         self.serial.register_callback(self.handle_callback, self.name, self.oid)
-        self.send_timer = self.serial.reactor.register_timer(
-            self.send_event, self.serial.reactor.NOW)
+        retry_time = self.send_event(self.min_query_time)
+        self.send_timer = reactor.register_timer(self.send_event, retry_time)
     def unregister(self):
         self.serial.unregister_callback(self.name, self.oid)
         self.serial.reactor.unregister_timer(self.send_timer)
     def send_event(self, eventtime):
         if self.response is not None:
             return self.serial.reactor.NEVER
+        if eventtime > self.min_query_time + self.TIMEOUT_TIME:
+            self.unregister()
+            if self.response is None:
+                self.mutex.unlock()
+            return self.serial.reactor.NEVER
         self.serial.raw_send(self.cmd, 0, 0, self.serial.default_cmd_queue)
         return eventtime + self.RETRY_TIME
     def handle_callback(self, params):
         last_sent_time = params['#sent_time']
-        if last_sent_time >= self.min_query_time:
+        if last_sent_time >= self.min_query_time and self.response is None:
             self.response = params
+            self.serial.reactor.register_async_callback(self.do_wake)
+    def do_wake(self, eventtime):
+        self.mutex.unlock()
     def get_response(self):
-        eventtime = self.serial.reactor.monotonic()
-        while self.response is None:
-            eventtime = self.serial.reactor.pause(eventtime + 0.05)
-            if eventtime > self.min_query_time + self.TIMEOUT_TIME:
-                self.unregister()
+        with self.mutex:
+            pass
+        if self.response is None:
             raise error("Timeout on wait for '%s' response" % (self.name,))
         self.unregister()
         return self.response