Add ArtifactNotFound exception

docs/api.rst

@@ -40,3 +40,5 @@ Artifact
    optuna_dashboard.artifact.upload_artifact
    optuna_dashboard.artifact.file_system.FileSystemBackend
    optuna_dashboard.artifact.boto3.Boto3Backend
+   optuna_dashboard.artifact.protocol.ArtifactBackend
+   optuna_dashboard.artifact.exceptions.ArtifactNotFound

optuna_dashboard/artifact/boto3.py

@@ -5,6 +5,8 @@ import shutil
 from typing import TYPE_CHECKING
 
 import boto3
+from botocore.exceptions import ClientError
+from optuna_dashboard.artifact.exceptions import ArtifactNotFound
 
 
 if TYPE_CHECKING:
@@ -41,7 +43,12 @@ class Boto3Backend:
         self.client = client or boto3.client("s3")
 
     def open(self, artifact_id: str) -> BinaryIO:
-        obj = self.client.get_object(Bucket=self.bucket, Key=artifact_id)
+        try:
+            obj = self.client.get_object(Bucket=self.bucket, Key=artifact_id)
+        except ClientError as e:
+            if _is_not_found_error(e):
+                raise ArtifactNotFound("not found") from e
+            raise
         body = obj.get("Body")
         assert body is not None
         return body  # type: ignore
@@ -58,7 +65,18 @@ class Boto3Backend:
         self.client.upload_fileobj(buf, self.bucket, artifact_id)
 
     def remove(self, artifact_id: str) -> None:
-        self.client.delete_object(Bucket=self.bucket, Key=artifact_id)
+        try:
+            self.client.delete_object(Bucket=self.bucket, Key=artifact_id)
+        except ClientError as e:
+            if _is_not_found_error(e):
+                raise ArtifactNotFound("not found") from e
+            raise
+
+
+def _is_not_found_error(e: ClientError) -> bool:
+    error_code = e.response.get("Error", {}).get("Code")
+    http_status_code = e.response.get("ResponseMetadata", {}).get("HTTPStatusCode")
+    return error_code == "NoSuchKey" or http_status_code == 404
 
 
 def _is_file_like_obj(obj: SupportsRead[bytes]) -> TypeGuard[IO[bytes]]:

optuna_dashboard/artifact/exceptions.py

@@ -0,0 +1,9 @@
+class ArtifactNotFound(Exception):
+    """Exception raised when an artifact is not found.
+
+    It is typically raised while calling
+    :meth:`~optuna_dashboard.artifact.protocol.ArtifactBackend.open` or
+    :meth:`~optuna_dashboard.artifact.protocol.ArtifactBackend.remove` methods.
+    """
+
+    ...

optuna_dashboard/artifact/file_system.py

@@ -2,11 +2,14 @@ from __future__ import annotations
 
 import os
 import shutil
-from typing import BinaryIO
 from typing import TYPE_CHECKING
 
+from optuna_dashboard.artifact.exceptions import ArtifactNotFound
+
 
 if TYPE_CHECKING:
+    from typing import BinaryIO
+
     from _typeshed import SupportsRead
 
 
@@ -34,7 +37,11 @@ class FileSystemBackend:
 
     def open(self, artifact_id: str) -> BinaryIO:
         filepath = os.path.join(self._base_path, artifact_id)
-        return open(filepath, "rb")
+        try:
+            f = open(filepath, "rb")
+        except FileNotFoundError as e:
+            raise ArtifactNotFound("not found") from e
+        return f
 
     def write(self, artifact_id: str, content_body: SupportsRead[bytes]) -> None:
         filepath = os.path.join(self._base_path, artifact_id)
@@ -43,7 +50,10 @@ class FileSystemBackend:
 
     def remove(self, artifact_id: str) -> None:
         filepath = os.path.join(self._base_path, artifact_id)
-        os.remove(filepath)
+        try:
+            os.remove(filepath)
+        except FileNotFoundError as e:
+            raise ArtifactNotFound("not found") from e
 
 
 if TYPE_CHECKING:

optuna_dashboard/artifact/protocol.py

@@ -1,20 +1,61 @@
 from __future__ import annotations
 
-from typing import BinaryIO
-from typing import Protocol
 from typing import TYPE_CHECKING
 
 
+try:
+    from typing import Protocol
+except ImportError:
+    from typing_extensions import Protocol
+
+
 if TYPE_CHECKING:
+    from typing import BinaryIO
+
     from _typeshed import SupportsRead
 
 
 class ArtifactBackend(Protocol):
+    """A protocol defining the interface for an artifact backend.
+
+    An artifact backend is responsible for managing the storage and retrieval
+    of artifact data. The backend should provide methods for opening, writing
+    and removing artifacts.
+    """
+
     def open(self, artifact_id: str) -> BinaryIO:
+        """Open the artifact identified by the artifact_id.
+
+        This method should return a binary file-like object in read mode, similar to
+        ``open(..., mode="rb")``. If the artifact does not exist, an
+        :exc:`~optuna_dashboard.artifact.exceptions.ArtifactNotFound` exception
+        should be raised.
+
+        Args:
+            artifact_id: The identifier of the artifact to open.
+
+        Returns:
+            BinaryIO: A binary file-like object that can be read from.
+        """
         ...
 
     def write(self, artifact_id: str, content_body: SupportsRead[bytes]) -> None:
+        """Save the content to the backend.
+
+        Args:
+            artifact_id: The identifier of the artifact to write to.
+            content_body: The content to write to the artifact.
+        """
         ...
 
     def remove(self, artifact_id: str) -> None:
+        """Remove the artifact identified by the artifact_id.
+
+        This method should delete the artifact from the backend. If the artifact does not
+        exist, an :exc:`~optuna_dashboard.artifact.exceptions.ArtifactNotFound` exception
+        may be raised.
+
+        Args:
+            artifact_id: The identifier of the artifact to remove.
+        """
         ...

python_tests/test_boto3_artifact.py

@@ -6,6 +6,7 @@ from unittest.mock import patch
 import boto3
 from moto import mock_s3
 from optuna_dashboard.artifact.boto3 import Boto3Backend
+from optuna_dashboard.artifact.exceptions import ArtifactNotFound
 
 
 @mock_s3
@@ -63,3 +64,8 @@ class Boto3BackendTestCase(TestCase):
         backend.remove(artifact_id)
         objects = self.s3_client.list_objects(Bucket=self.bucket_name).get("Contents", [])
         assert len([obj for obj in objects if obj["Key"] == artifact_id]) == 0
+
+    def test_file_not_found_exception(self) -> None:
+        backend = Boto3Backend(self.bucket_name)
+        with self.assertRaises(ArtifactNotFound):
+            backend.open("not-found-id")

python_tests/test_file_system_artifact.py

@@ -3,6 +3,7 @@ import tempfile
 from unittest import TestCase
 
 from optuna_dashboard.artifact.file_system import FileSystemBackend
+from optuna_dashboard.artifact.exceptions import ArtifactNotFound
 
 
 class FileSystemBackendTestCase(TestCase):
@@ -20,3 +21,10 @@ class FileSystemBackendTestCase(TestCase):
         with backend.open(artifact_id) as f:
             actual = f.read()
         self.assertEqual(actual, dummy_content)
+
+    def test_file_not_found(self) -> None:
+        backend = FileSystemBackend(self.dir.name)
+        with self.assertRaises(ArtifactNotFound):
+            backend.open("not-found-id")
+        with self.assertRaises(ArtifactNotFound):
+            backend.remove("not-found-id")