SNOW-799408: Close temp file handle before removing temp cache file (#…

…1582)

DESCRIPTION.md

@@ -10,6 +10,7 @@ Source code is also available at: https://github.com/snowflakedb/snowflake-conne
 
 - v3.0.5(TBD)
   - Added the ability to read Snowflake's central configuration file.
+  - Improved OCSP response caching to remove tmp cache files on Windows.
 
 - v3.0.4(May 23,2023)
   - Fixed a bug in which `cursor.execute()` could modify the argument statement_params dictionary object when executing a multistatement query.

src/snowflake/connector/cache.py

@@ -524,6 +524,12 @@ def _save(self, load_first: bool = True) -> bool:
                         prefix=fname,
                         dir=_dir,
                     )
+                    # tmp_file is an opened OS level handle, which means we need to close it manually.
+                    # https://docs.python.org/3/library/tempfile.html#tempfile.mkstemp
+                    # ideally we shall just use the tmp_file fd to write,
+                    # however, using os.write(tmp_file, bytes) causes seg fault during garbage collection when exiting
+                    # python program.
+                    # thus we fall back to the approach using the normal open() method to open a file and write.
                     with open(tmp_file, "wb") as w_file:
                         pickle.dump(self, w_file)
                     # We write to a tmp file and then move it to have atomic write
@@ -532,6 +538,14 @@ def _save(self, load_first: bool = True) -> bool:
                         getmtime(self.file_path),
                     )
                     return True
+                except NameError:
+                    # note: when exiting python program, garbage collection will kick in
+                    # leading to `open` being garbage collected,
+                    # calling `open` raises NameError, we close the tmp file fd here to release the tmp file fd
+                    try:
+                        os.close(tmp_file)
+                    except OSError:
+                        pass
                 except OSError as o_err:
                     raise PermissionError(
                         o_err.errno,

test/extras/run.py

@@ -1,11 +1,14 @@
 #
 # Copyright (c) 2012-2023 Snowflake Computing Inc. All rights reserved.
 #
-
+import os
 import pathlib
+import platform
 import subprocess
 import sys
 
+import snowflake.connector.ocsp_snowflake
+
 # This script run every Python file in this directory other than this
 #  one in a subprocess and checks their exit codes
 
@@ -23,3 +26,25 @@
             ]
         )
         sub_process.check_returncode()
+        ocsp_cache_dir_path = pathlib.Path(
+            snowflake.connector.ocsp_snowflake.OCSP_RESPONSE_VALIDATION_CACHE.file_path
+        ).parent
+        cache_files = set(os.listdir(ocsp_cache_dir_path))
+        # This is to test SNOW-79940, making sure tmp files are removed
+        # Windows does not have ocsp_response_validation_cache.lock
+        assert (
+            cache_files
+            == {
+                "ocsp_response_validation_cache.lock",
+                "ocsp_response_validation_cache",
+                "ocsp_response_cache.json",
+            }
+            and not platform.system() == "Windows"
+        ) or (
+            cache_files
+            == {
+                "ocsp_response_validation_cache",
+                "ocsp_response_cache.json",
+            }
+            and platform.system() == "Windows"
+        )