Update payload size when updating socket path (#807)

* Update payload size when updating socket path

* Add a test case

Author: vickenty

datadog/dogstatsd/base.py

@@ -319,20 +319,16 @@ def __init__(
             self._enabled = False
 
         # Connection
-        self._max_payload_size = max_buffer_len
+        self._max_buffer_len = max_buffer_len
         self.socket_timeout = socket_timeout
         if socket_path is not None:
             self.socket_path = socket_path  # type: Optional[text]
             self.host = None
             self.port = None
-            if not self._max_payload_size:
-                self._max_payload_size = UDS_OPTIMAL_PAYLOAD_LENGTH
         else:
             self.socket_path = None
             self.host = self.resolve_host(host, use_default_route)
             self.port = int(port)
-            if not self._max_payload_size:
-                self._max_payload_size = UDP_OPTIMAL_PAYLOAD_LENGTH
 
         self.telemetry_socket_path = telemetry_socket_path
         self.telemetry_host = None
@@ -420,8 +416,14 @@ def socket_path(self):
 
     @socket_path.setter
     def socket_path(self, path):
-        self._socket_path = path
-        self._transport = "udp" if path is None else "uds"
+        with self._socket_lock:
+            self._socket_path = path
+            if path is None:
+                self._transport = "udp"
+                self._max_payload_size = self._max_buffer_len or UDP_OPTIMAL_PAYLOAD_LENGTH
+            else:
+                self._transport = "uds"
+                self._max_payload_size = self._max_buffer_len or UDS_OPTIMAL_PAYLOAD_LENGTH
 
     def enable_background_sender(self, sender_queue_size=0, sender_queue_timeout=0):
         """

tests/unit/dogstatsd/test_statsd.py

@@ -1951,3 +1951,9 @@ def test_telemetry_api(self):
         self.assertEqual(statsd.packets_dropped, 0)
         self.assertEqual(statsd.packets_dropped_queue, 0)
         self.assertEqual(statsd.packets_dropped_writer, 0)
+
+    def test_max_payload_size(self):
+        statsd = DogStatsd(socket_path=None, port=8125)
+        self.assertEqual(statsd._max_payload_size, UDP_OPTIMAL_PAYLOAD_LENGTH)
+        statsd.socket_path = "/foo"
+        self.assertEqual(statsd._max_payload_size, UDS_OPTIMAL_PAYLOAD_LENGTH)