Use time.monotonic instead of time.time for heartbeat code.

discord/gateway.py

@@ -62,13 +62,13 @@ class KeepAliveHandler(threading.Thread):
         self.shard_id = shard_id
         self.msg = 'Keeping websocket alive with sequence %s.'
         self._stop_ev = threading.Event()
-        self._last_ack = time.time()
-        self._last_send = time.time()
+        self._last_ack = time.monotonic()
+        self._last_send = time.monotonic()
         self.heartbeat_timeout = ws._max_heartbeat_timeout
 
     def run(self):
         while not self._stop_ev.wait(self.interval):
-            if self._last_ack + self.heartbeat_timeout < time.time():
+            if self._last_ack + self.heartbeat_timeout < time.monotonic():
                 log.warn("Shard ID %s has stopped responding to the gateway. Closing and restarting." % self.shard_id)
                 coro = self.ws.close(1006)
                 f = compat.run_coroutine_threadsafe(coro, loop=self.ws.loop)
@@ -91,7 +91,7 @@ class KeepAliveHandler(threading.Thread):
             except Exception:
                 self.stop()
             else:
-                self._last_send = time.time()
+                self._last_send = time.monotonic()
 
     def get_payload(self):
         return {
@@ -103,7 +103,7 @@ class KeepAliveHandler(threading.Thread):
         self._stop_ev.set()
 
     def ack(self):
-        self._last_ack = time.time()
+        self._last_ack = time.monotonic()
 
 class VoiceKeepAliveHandler(KeepAliveHandler):
     def __init__(self, *args, **kwargs):