Merge pull request #63 from raulgomis/fix/changeset-file-race-condition

Fix changeset file race condition

Author: raulgomis

.semversioner/next-release/patch-20250723122218419618.json

@@ -0,0 +1,4 @@
+{
+  "type": "patch",
+  "description": "Fix file creation race condition"
+}

semversioner/storage.py

@@ -157,17 +157,22 @@ def create_changeset(self, change: Changeset) -> str:
             Absolute path of the file generated.
         """
 
-        filename = None
-        while (filename is None or os.path.isfile(os.path.join(self.next_release_path, filename))):
+        # Retry loop with atomic file creation to prevent race conditions
+        while True:
             filename = '{type_name}-{datetime}.json'.format(
                 type_name=change.type,
                 datetime="{:%Y%m%d%H%M%S%f}".format(datetime.now(timezone.utc))
             )
-
-        with open(os.path.join(self.next_release_path, filename), 'w') as f:
-            f.write(json.dumps(change, cls=EnhancedJSONEncoder, indent=2) + "\n")
-
-        return os.path.join(self.next_release_path, filename)
+            full_path = os.path.join(self.next_release_path, filename)
+
+            try:
+                # Use 'x' mode for exclusive creation - fails if file already exists
+                with open(full_path, 'x') as f:
+                    f.write(json.dumps(change, cls=EnhancedJSONEncoder, indent=2) + "\n")
+                return full_path
+            except FileExistsError:
+                # File already exists, retry with a new timestamp
+                continue
 
     def remove_all_changesets(self) -> None:
         click.echo("Removing changeset files in '" + self.next_release_path + "' directory.")

tests/core_test.py

@@ -2,6 +2,7 @@
 import shutil
 import os
 import tempfile
+import threading
 
 from semversioner import Semversioner
 from semversioner import ReleaseStatus
@@ -88,6 +89,40 @@ def test_release_stress(self) -> None:
         releaser.release()
         self.assertEqual(releaser.get_status(), ReleaseStatus(version='1.0.0', next_version=None, unreleased_changes=[]))
 
+    def test_concurrent_changeset_creation_race_condition(self) -> None:
+        """
+        Test that concurrent changeset creation does not result in file creation race conditions.
+        """
+        releaser = Semversioner(self.directory_name)
+        num_threads = 20
+        threads = []
+        descriptions = [f"desc {i}" for i in range(num_threads)]
+
+        def add_change(desc: str) -> None:
+            # Each thread tries to add a changeset with a unique description
+            releaser.add_change("patch", desc)
+
+        for desc in descriptions:
+            t = threading.Thread(target=add_change, args=(desc,))
+            threads.append(t)
+            t.start()
+
+        for t in threads:
+            t.join()
+
+        # Check that all changeset files were created and are unique
+        files = [f for f in os.listdir(self.next_release_dirname) if f.endswith('.json')]
+        self.assertEqual(len(files), num_threads)
+        # Optionally, check that all descriptions are present
+        found_descriptions = set()
+        for f in files:
+            with open(os.path.join(self.next_release_dirname, f)) as fh:
+                data = fh.read()
+                for desc in descriptions:
+                    if desc in data:
+                        found_descriptions.add(desc)
+        self.assertEqual(set(descriptions), found_descriptions)
+
     def test_is_deprecated(self) -> None:
         releaser = Semversioner(self.directory_name)
         self.assertFalse(releaser.is_deprecated())