tests: retry os.rename on PermissionError failure in lttng_live_server.py

[babeltrace.git] / tests / data / plugins / src.ctf.lttng-live / lttng_live_server.py

diff --git a/tests/data/plugins/src.ctf.lttng-live/lttng_live_server.py b/tests/data/plugins/src.ctf.lttng-live/lttng_live_server.py
index 91e1cc8a6f446b4df30e78520a7cfebffb26c45c..573c47e31914bb38557cd56f816ed7d5c47128ef 100644 (file)
--- a/tests/data/plugins/src.ctf.lttng-live/lttng_live_server.py
+++ b/tests/data/plugins/src.ctf.lttng-live/lttng_live_server.py
@@ -26,6 +26,7 @@ import logging
 import os
 import os.path
 import re
+import time
 import socket
 import struct
 import sys
@@ -1344,13 +1345,41 @@ class LttngLiveServer:
         with tempfile.NamedTemporaryFile(mode='w', delete=False) as tmp_port_file:
             print(self._server_port, end='', file=tmp_port_file)
 
-        # Rename temporary file to real file
-        os.replace(tmp_port_file.name, port_filename)
-        logging.info(
-            'Renamed port file: src-path="{}", dst-path="{}"'.format(
-                tmp_port_file.name, port_filename
-            )
-        )
+        # Rename temporary file to real file.
+        #
+        # For unknown reasons, on Windows, moving the port file from its
+        # temporary location to its final location (where the user of
+        # the server expects it to appear) may raise a `PermissionError`
+        # exception.
+        #
+        # We suppose it's possible that something in the Windows kernel
+        # hasn't completely finished using the file when we try to move
+        # it.
+        #
+        # Use a wait-and-retry scheme as a (bad) workaround.
+        num_attempts = 5
+        retry_delay_s = 1
+
+        for attempt in reversed(range(num_attempts)):
+            try:
+                os.replace(tmp_port_file.name, port_filename)
+                logging.info(
+                    'Renamed port file: src-path="{}", dst-path="{}"'.format(
+                        tmp_port_file.name, port_filename
+                    )
+                )
+                return
+            except PermissionError:
+                logging.info(
+                    'Permission error while attempting to rename port file; retrying in {} second: src-path="{}", dst-path="{}"'.format(
+                        retry_delay_s, tmp_port_file.name, port_filename
+                    )
+                )
+
+                if attempt == 0:
+                    raise
+
+                time.sleep(retry_delay_s)
 
 
 # A tracing session descriptor.