Fix race condition causing ENOPRSTATS

ogr/services/pagure/pull_request.py

@@ -3,6 +3,7 @@
 
 import datetime
 import logging
+from time import sleep
 from typing import Any, Optional, Union
 
 from ogr.abstract import CommitFlag, CommitStatus, PRComment, PRStatus, PullRequest
@@ -191,7 +192,20 @@ def get(project: "ogr_pagure.PagureProject", pr_id: int) -> "PullRequest":
         return PagurePullRequest(raw_pr, project)
 
     @staticmethod
-    def get_files_diff(project: "ogr_pagure.PagureProject", pr_id: int) -> dict:
+    def get_files_diff(
+        project: "ogr_pagure.PagureProject",
+        pr_id: int,
+        retries=3,
+        wait_seconds=3,
+    ) -> dict:
+        """Collect all the changes in the PR and deal with ENOPRSTATS exception.
+        While the PR is changing its status from open to merged
+        exception can be raised by the Pagure service.
+        Wait for a while to see if we can manage to access changes adjusting the
+        retries and wait_seconds parameters.
+
+        """
+        attempt = 0
         try:
             return project._call_project_api(
                 "pull-request",
@@ -201,7 +215,18 @@ def get_files_diff(project: "ogr_pagure.PagureProject", pr_id: int) -> dict:
             )
         except PagureAPIException as ex:
             if "No statistics" in ex.pagure_error:
-                return {}
+                # this may be a race condition, try once more
+                logger.error(
+                    f"While retrieving PR diff Pagure returned ENOPRSTATS. {ex}",
+                )
+                if attempt <= retries:
+                    logger.error(
+                        f"Trying again; attempt={attempt} after {wait_seconds}seconds",
+                    )
+                    attempt += 1
+                    sleep(wait_seconds)
+                else:
+                    raise ex
             raise ex
 
     @staticmethod

tests/integration/pagure/test_pull_requests.py

@@ -1,9 +1,11 @@
 # Copyright Contributors to the Packit project.
 # SPDX-License-Identifier: MIT
 
+import pytest
 from requre.online_replacing import record_requests_for_all_methods
 
 from ogr.abstract import CommitStatus, PRStatus
+from ogr.exceptions import PagureAPIException
 from tests.integration.pagure.base import PagureTests
 
 
@@ -125,6 +127,5 @@ def test_pr_diff(self):
         assert "README.md" in diff
 
     def test_pr_diff_empty_diff(self):
-        diff = self.ogr_project.get_pr_files_diff(6)
-        assert isinstance(diff, dict)
-        assert diff == {}
+        with pytest.raises(PagureAPIException) as _:
+            self.ogr_project.get_pr_files_diff(6, retries=1)