From 2d3398a86ad85b572c54395ef351e096bf3703d9 Mon Sep 17 00:00:00 2001
From: Taner Topal <taner@flower.ai>
Date: Sun, 16 Jun 2024 23:15:37 +0200
Subject: [PATCH 01/17] feat(framework:skip) Add Flower File Storage interface
 and disk based implementation

---
 src/py/flwr/server/superlink/ffs/__init__.py |  24 ++++
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 119 ++++++++++++++++
 src/py/flwr/server/superlink/ffs/ffs.py      |  78 +++++++++++
 src/py/flwr/server/superlink/ffs/ffs_test.py | 139 +++++++++++++++++++
 4 files changed, 360 insertions(+)
 create mode 100644 src/py/flwr/server/superlink/ffs/__init__.py
 create mode 100644 src/py/flwr/server/superlink/ffs/disk_ffs.py
 create mode 100644 src/py/flwr/server/superlink/ffs/ffs.py
 create mode 100644 src/py/flwr/server/superlink/ffs/ffs_test.py

diff --git a/src/py/flwr/server/superlink/ffs/__init__.py b/src/py/flwr/server/superlink/ffs/__init__.py
new file mode 100644
index 00000000000..4b2ee7a2e2a
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/__init__.py
@@ -0,0 +1,24 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Flower File Storage for large objects."""
+
+
+from .disk_ffs import DiskFfs as DiskFfs
+from .ffs import Ffs as Ffs
+
+__all__ = [
+    "Ffs",
+    "DiskFfs",
+]
diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
new file mode 100644
index 00000000000..833654bf64c
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -0,0 +1,119 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Disk based Flower File Storage."""
+
+import hashlib
+import json
+import os
+from typing import Dict, List, Tuple
+
+from flwr.server.superlink.ffs.ffs import Ffs
+
+
+def write_dict_to_file(data_dict, file_path):
+    """Write a Dict to a file in JSON format."""
+    with open(file_path, "w") as file:
+        json.dump(data_dict, file)
+
+
+def read_dict_from_file(file_path):
+    """Read a Dict from a JSON file."""
+    with open(file_path) as file:
+        data_dict = json.load(file)
+    return data_dict
+
+
+class DiskFfs(Ffs):  # pylint: disable=R0904
+    """Disk based Flower File Storage interface for large objects."""
+
+    def __init__(self, base_dir: str) -> None:
+        """Create a new DiskFfs instance.
+
+        Parameters
+        ----------
+        base_dir : string
+            The base directory to store the objects.
+        """
+        self.base_dir = base_dir
+
+    def put(self, content: bytes, meta: Dict[str, str]) -> str:
+        """Store bytes and metadata. Return sha256hex hash of data as str.
+
+        Parameters
+        ----------
+        content : bytes
+            The content to be stored.
+        meta : Dict[str, str]
+            The metadata to be stored.
+
+        Returns
+        -------
+        sha256hex : string
+            The sha256hex hash of the content.
+        """
+        content_hash = hashlib.sha256(content).hexdigest()
+
+        with open(os.path.join(self.base_dir, content_hash), "wb") as file:
+            file.write(content)
+
+        write_dict_to_file(meta, os.path.join(self.base_dir, f"{content_hash}.META"))
+
+        return content_hash
+
+    def get(self, key: str) -> Tuple[bytes, Dict[str, str]]:
+        """Return tuple containing the object and it's meta fields.
+
+        Parameters
+        ----------
+        hash : string
+            The sha256hex hash of the object to be retrieved.
+
+        Returns
+        -------
+        Tuple[bytes, Dict[str, str]]
+            A tuple containing the object and it's metadata.
+        """
+        with open(os.path.join(self.base_dir, key), "rb") as file:
+            content = file.read()
+
+        meta = read_dict_from_file(os.path.join(self.base_dir, f"{key}.META"))
+
+        return content, meta
+
+    def delete(self, key: str) -> None:
+        """Delete object with hash.
+
+        Parameters
+        ----------
+        hash : string
+            The sha256hex hash of the object to be deleted.
+        """
+        os.remove(os.path.join(self.base_dir, key))
+        os.remove(os.path.join(self.base_dir, f"{key}.META"))
+
+    def list(self) -> List[str]:
+        """List all keys.
+
+        Can be used to list all keys in the storage and e.g. to clean up
+        the storage with the delete method.
+
+        Returns
+        -------
+        List[str]
+            A list of all keys.
+        """
+        return [
+            item for item in os.listdir(self.base_dir) if not item.endswith(".META")
+        ]
diff --git a/src/py/flwr/server/superlink/ffs/ffs.py b/src/py/flwr/server/superlink/ffs/ffs.py
new file mode 100644
index 00000000000..d114cee0f0c
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/ffs.py
@@ -0,0 +1,78 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Abstract base class for Flower File Storage interface."""
+
+
+import abc
+from typing import Dict, List, Tuple
+
+
+class Ffs(abc.ABC):  # pylint: disable=R0904
+    """Abstract Flower File Storage interface for large objects."""
+
+    @abc.abstractmethod
+    def put(self, content: bytes, meta: Dict[str, str]) -> str:
+        """Store bytes and metadata. Return sha256hex hash of data as str.
+
+        Parameters
+        ----------
+        content : bytes
+            The content to be stored.
+        meta : Dict[str, str]
+            The metadata to be stored.
+
+        Returns
+        -------
+        sha256hex : string
+            The sha256hex hash of the content.
+        """
+
+    @abc.abstractmethod
+    def get(self, key: str) -> Tuple[bytes, Dict[str, str]]:
+        """Return tuple containing the object and it's meta fields.
+
+        Parameters
+        ----------
+        hash : string
+            The sha256hex hash of the object to be retrieved.
+
+        Returns
+        -------
+        Tuple[bytes, Dict[str, str]]
+            A tuple containing the object and it's metadata.
+        """
+
+    @abc.abstractmethod
+    def delete(self, key: str) -> None:
+        """Delete object with hash.
+
+        Parameters
+        ----------
+        hash : string
+            The sha256hex hash of the object to be deleted.
+        """
+
+    @abc.abstractmethod
+    def list(self) -> List[str]:
+        """List all keys.
+
+        Can be used to list all keys in the storage and e.g. to clean up
+        the storage with the delete method.
+
+        Returns
+        -------
+        List[str]
+            A list of all keys.
+        """
diff --git a/src/py/flwr/server/superlink/ffs/ffs_test.py b/src/py/flwr/server/superlink/ffs/ffs_test.py
new file mode 100644
index 00000000000..fef765c7ac9
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/ffs_test.py
@@ -0,0 +1,139 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Tests all Ffs implemenations have to conform to."""
+# pylint: disable=invalid-name, disable=R0904
+
+import hashlib
+import json
+import os
+import tempfile
+import unittest
+from abc import abstractmethod
+
+from flwr.server.superlink.ffs import DiskFfs, Ffs
+
+
+class FfsTest(unittest.TestCase):
+    """Test all ffs implementations."""
+
+    # This is to True in each child class
+    __test__ = False
+
+    @abstractmethod
+    def ffs_factory(self) -> Ffs:
+        """Provide Ffs implementation to test."""
+        raise NotImplementedError()
+
+    def test_put(self) -> None:
+        """Test if object can be stored."""
+        # Prepare
+        ffs: Ffs = self.ffs_factory()
+        content = b"content"
+        hash_expected = hashlib.sha256(content).hexdigest()
+
+        # Execute
+        hash_actual = ffs.put(b"content", {"meta": "data"})
+
+        # Assert
+        assert isinstance(hash_actual, str)
+        assert len(hash_actual) == 64
+        assert hash_actual == hash_expected
+
+        # Check if file was created
+        assert [hash_expected, f"{hash_expected}.META"] == os.listdir(self.tmp_dir.name)
+
+    def test_get(self) -> None:
+        """Test if object can be retrieved."""
+        # Prepare
+        ffs: Ffs = self.ffs_factory()
+        content_expected = b"content"
+        hash_expected = hashlib.sha256(content_expected).hexdigest()
+        meta_expected = {}
+
+        with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
+            file.write(content_expected)
+
+        with open(
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+        ) as file:
+            json.dump(meta_expected, file)
+
+        # Execute
+        content_actual, meta_actual = ffs.get(hash_expected)
+
+        # Assert
+        assert content_actual == content_expected
+        assert meta_actual == meta_expected
+
+    def test_delete(self) -> None:
+        """Test if object can be deleted."""
+        # Prepare
+        ffs: Ffs = self.ffs_factory()
+        content_expected = b"content"
+        hash_expected = hashlib.sha256(content_expected).hexdigest()
+        meta_expected = {}
+
+        with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
+            file.write(content_expected)
+
+        with open(
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+        ) as file:
+            json.dump(meta_expected, file)
+
+        # Execute
+        ffs.delete(hash_expected)
+
+        # Assert
+        assert [] == os.listdir(self.tmp_dir.name)
+
+    def test_list(self) -> None:
+        """Test if object hashes can be listed."""
+        # Prepare
+        ffs: Ffs = self.ffs_factory()
+        content_expected = b"content"
+        hash_expected = hashlib.sha256(content_expected).hexdigest()
+        meta_expected = {}
+
+        with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
+            file.write(content_expected)
+
+        with open(
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+        ) as file:
+            json.dump(meta_expected, file)
+
+        # Execute
+        hashes = ffs.list()
+
+        # Assert
+        assert [hash_expected] == hashes
+
+
+class DiskFfsTest(FfsTest, unittest.TestCase):
+    """Test DiskFfs implementation."""
+
+    __test__ = True
+
+    def ffs_factory(self) -> DiskFfs:
+        """Return SqliteState with file-based database."""
+        # pylint: disable-next=consider-using-with,attribute-defined-outside-init
+        self.tmp_dir = tempfile.TemporaryDirectory()
+        ffs = DiskFfs(self.tmp_dir.name)
+        return ffs
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)

From 8f4d7c26f1b841d433f35cf7a030dc597f10660b Mon Sep 17 00:00:00 2001
From: Taner Topal <taner@flower.ai>
Date: Sun, 16 Jun 2024 23:15:37 +0200
Subject: [PATCH 02/17] feat(framework:skip) Add Flower File Storage interface
 and disk based implementation

---
 src/py/flwr/server/superlink/ffs/__init__.py |  24 ++++
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 119 ++++++++++++++++
 src/py/flwr/server/superlink/ffs/ffs.py      |  78 +++++++++++
 src/py/flwr/server/superlink/ffs/ffs_test.py | 139 +++++++++++++++++++
 4 files changed, 360 insertions(+)
 create mode 100644 src/py/flwr/server/superlink/ffs/__init__.py
 create mode 100644 src/py/flwr/server/superlink/ffs/disk_ffs.py
 create mode 100644 src/py/flwr/server/superlink/ffs/ffs.py
 create mode 100644 src/py/flwr/server/superlink/ffs/ffs_test.py

diff --git a/src/py/flwr/server/superlink/ffs/__init__.py b/src/py/flwr/server/superlink/ffs/__init__.py
new file mode 100644
index 00000000000..4b2ee7a2e2a
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/__init__.py
@@ -0,0 +1,24 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Flower File Storage for large objects."""
+
+
+from .disk_ffs import DiskFfs as DiskFfs
+from .ffs import Ffs as Ffs
+
+__all__ = [
+    "Ffs",
+    "DiskFfs",
+]
diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
new file mode 100644
index 00000000000..46e102639d4
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -0,0 +1,119 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Disk based Flower File Storage."""
+
+import hashlib
+import json
+import os
+from typing import Dict, List, Tuple
+
+from flwr.server.superlink.ffs.ffs import Ffs
+
+
+def write_dict_to_file(data_dict: Dict[str, str], file_path: str) -> None:
+    """Write a Dict to a file in JSON format."""
+    with open(file_path, "w") as file:
+        json.dump(data_dict, file)
+
+
+def read_dict_from_file(file_path: str) -> Dict[str, str]:
+    """Read a Dict from a JSON file."""
+    with open(file_path) as file:
+        data_dict = json.load(file)
+    return data_dict
+
+
+class DiskFfs(Ffs):  # pylint: disable=R0904
+    """Disk based Flower File Storage interface for large objects."""
+
+    def __init__(self, base_dir: str) -> None:
+        """Create a new DiskFfs instance.
+
+        Parameters
+        ----------
+        base_dir : string
+            The base directory to store the objects.
+        """
+        self.base_dir = base_dir
+
+    def put(self, content: bytes, meta: Dict[str, str]) -> str:
+        """Store bytes and metadata. Return sha256hex hash of data as str.
+
+        Parameters
+        ----------
+        content : bytes
+            The content to be stored.
+        meta : Dict[str, str]
+            The metadata to be stored.
+
+        Returns
+        -------
+        sha256hex : string
+            The sha256hex hash of the content.
+        """
+        content_hash = hashlib.sha256(content).hexdigest()
+
+        with open(os.path.join(self.base_dir, content_hash), "wb") as file:
+            file.write(content)
+
+        write_dict_to_file(meta, os.path.join(self.base_dir, f"{content_hash}.META"))
+
+        return content_hash
+
+    def get(self, key: str) -> Tuple[bytes, Dict[str, str]]:
+        """Return tuple containing the object and it's meta fields.
+
+        Parameters
+        ----------
+        hash : string
+            The sha256hex hash of the object to be retrieved.
+
+        Returns
+        -------
+        Tuple[bytes, Dict[str, str]]
+            A tuple containing the object and it's metadata.
+        """
+        with open(os.path.join(self.base_dir, key), "rb") as file:
+            content = file.read()
+
+        meta = read_dict_from_file(os.path.join(self.base_dir, f"{key}.META"))
+
+        return content, meta
+
+    def delete(self, key: str) -> None:
+        """Delete object with hash.
+
+        Parameters
+        ----------
+        hash : string
+            The sha256hex hash of the object to be deleted.
+        """
+        os.remove(os.path.join(self.base_dir, key))
+        os.remove(os.path.join(self.base_dir, f"{key}.META"))
+
+    def list(self) -> List[str]:
+        """List all keys.
+
+        Can be used to list all keys in the storage and e.g. to clean up
+        the storage with the delete method.
+
+        Returns
+        -------
+        List[str]
+            A list of all keys.
+        """
+        return [
+            item for item in os.listdir(self.base_dir) if not item.endswith(".META")
+        ]
diff --git a/src/py/flwr/server/superlink/ffs/ffs.py b/src/py/flwr/server/superlink/ffs/ffs.py
new file mode 100644
index 00000000000..d114cee0f0c
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/ffs.py
@@ -0,0 +1,78 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Abstract base class for Flower File Storage interface."""
+
+
+import abc
+from typing import Dict, List, Tuple
+
+
+class Ffs(abc.ABC):  # pylint: disable=R0904
+    """Abstract Flower File Storage interface for large objects."""
+
+    @abc.abstractmethod
+    def put(self, content: bytes, meta: Dict[str, str]) -> str:
+        """Store bytes and metadata. Return sha256hex hash of data as str.
+
+        Parameters
+        ----------
+        content : bytes
+            The content to be stored.
+        meta : Dict[str, str]
+            The metadata to be stored.
+
+        Returns
+        -------
+        sha256hex : string
+            The sha256hex hash of the content.
+        """
+
+    @abc.abstractmethod
+    def get(self, key: str) -> Tuple[bytes, Dict[str, str]]:
+        """Return tuple containing the object and it's meta fields.
+
+        Parameters
+        ----------
+        hash : string
+            The sha256hex hash of the object to be retrieved.
+
+        Returns
+        -------
+        Tuple[bytes, Dict[str, str]]
+            A tuple containing the object and it's metadata.
+        """
+
+    @abc.abstractmethod
+    def delete(self, key: str) -> None:
+        """Delete object with hash.
+
+        Parameters
+        ----------
+        hash : string
+            The sha256hex hash of the object to be deleted.
+        """
+
+    @abc.abstractmethod
+    def list(self) -> List[str]:
+        """List all keys.
+
+        Can be used to list all keys in the storage and e.g. to clean up
+        the storage with the delete method.
+
+        Returns
+        -------
+        List[str]
+            A list of all keys.
+        """
diff --git a/src/py/flwr/server/superlink/ffs/ffs_test.py b/src/py/flwr/server/superlink/ffs/ffs_test.py
new file mode 100644
index 00000000000..fef765c7ac9
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/ffs_test.py
@@ -0,0 +1,139 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Tests all Ffs implemenations have to conform to."""
+# pylint: disable=invalid-name, disable=R0904
+
+import hashlib
+import json
+import os
+import tempfile
+import unittest
+from abc import abstractmethod
+
+from flwr.server.superlink.ffs import DiskFfs, Ffs
+
+
+class FfsTest(unittest.TestCase):
+    """Test all ffs implementations."""
+
+    # This is to True in each child class
+    __test__ = False
+
+    @abstractmethod
+    def ffs_factory(self) -> Ffs:
+        """Provide Ffs implementation to test."""
+        raise NotImplementedError()
+
+    def test_put(self) -> None:
+        """Test if object can be stored."""
+        # Prepare
+        ffs: Ffs = self.ffs_factory()
+        content = b"content"
+        hash_expected = hashlib.sha256(content).hexdigest()
+
+        # Execute
+        hash_actual = ffs.put(b"content", {"meta": "data"})
+
+        # Assert
+        assert isinstance(hash_actual, str)
+        assert len(hash_actual) == 64
+        assert hash_actual == hash_expected
+
+        # Check if file was created
+        assert [hash_expected, f"{hash_expected}.META"] == os.listdir(self.tmp_dir.name)
+
+    def test_get(self) -> None:
+        """Test if object can be retrieved."""
+        # Prepare
+        ffs: Ffs = self.ffs_factory()
+        content_expected = b"content"
+        hash_expected = hashlib.sha256(content_expected).hexdigest()
+        meta_expected = {}
+
+        with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
+            file.write(content_expected)
+
+        with open(
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+        ) as file:
+            json.dump(meta_expected, file)
+
+        # Execute
+        content_actual, meta_actual = ffs.get(hash_expected)
+
+        # Assert
+        assert content_actual == content_expected
+        assert meta_actual == meta_expected
+
+    def test_delete(self) -> None:
+        """Test if object can be deleted."""
+        # Prepare
+        ffs: Ffs = self.ffs_factory()
+        content_expected = b"content"
+        hash_expected = hashlib.sha256(content_expected).hexdigest()
+        meta_expected = {}
+
+        with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
+            file.write(content_expected)
+
+        with open(
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+        ) as file:
+            json.dump(meta_expected, file)
+
+        # Execute
+        ffs.delete(hash_expected)
+
+        # Assert
+        assert [] == os.listdir(self.tmp_dir.name)
+
+    def test_list(self) -> None:
+        """Test if object hashes can be listed."""
+        # Prepare
+        ffs: Ffs = self.ffs_factory()
+        content_expected = b"content"
+        hash_expected = hashlib.sha256(content_expected).hexdigest()
+        meta_expected = {}
+
+        with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
+            file.write(content_expected)
+
+        with open(
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+        ) as file:
+            json.dump(meta_expected, file)
+
+        # Execute
+        hashes = ffs.list()
+
+        # Assert
+        assert [hash_expected] == hashes
+
+
+class DiskFfsTest(FfsTest, unittest.TestCase):
+    """Test DiskFfs implementation."""
+
+    __test__ = True
+
+    def ffs_factory(self) -> DiskFfs:
+        """Return SqliteState with file-based database."""
+        # pylint: disable-next=consider-using-with,attribute-defined-outside-init
+        self.tmp_dir = tempfile.TemporaryDirectory()
+        ffs = DiskFfs(self.tmp_dir.name)
+        return ffs
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)

From 5f579465e5395f769797f4df7d55de2697a5887a Mon Sep 17 00:00:00 2001
From: Taner Topal <taner@flower.ai>
Date: Sun, 16 Jun 2024 23:53:21 +0200
Subject: [PATCH 03/17] Fix type errors

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py |  6 +++---
 src/py/flwr/server/superlink/ffs/ffs_test.py | 21 ++++++++++++++------
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index 46e102639d4..aab5ba3d424 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -24,14 +24,14 @@
 
 def write_dict_to_file(data_dict: Dict[str, str], file_path: str) -> None:
     """Write a Dict to a file in JSON format."""
-    with open(file_path, "w") as file:
+    with open(file_path, "w", encoding="utf-8") as file:
         json.dump(data_dict, file)
 
 
 def read_dict_from_file(file_path: str) -> Dict[str, str]:
     """Read a Dict from a JSON file."""
-    with open(file_path) as file:
-        data_dict = json.load(file)
+    with open(file_path, encoding="utf-8") as file:
+        data_dict: Dict[str, str] = json.load(file)
     return data_dict
 
 
diff --git a/src/py/flwr/server/superlink/ffs/ffs_test.py b/src/py/flwr/server/superlink/ffs/ffs_test.py
index fef765c7ac9..3baacbe0489 100644
--- a/src/py/flwr/server/superlink/ffs/ffs_test.py
+++ b/src/py/flwr/server/superlink/ffs/ffs_test.py
@@ -21,6 +21,7 @@
 import tempfile
 import unittest
 from abc import abstractmethod
+from typing import Dict
 
 from flwr.server.superlink.ffs import DiskFfs, Ffs
 
@@ -31,6 +32,8 @@ class FfsTest(unittest.TestCase):
     # This is to True in each child class
     __test__ = False
 
+    tmp_dir: tempfile.TemporaryDirectory  # type: ignore
+
     @abstractmethod
     def ffs_factory(self) -> Ffs:
         """Provide Ffs implementation to test."""
@@ -60,13 +63,15 @@ def test_get(self) -> None:
         ffs: Ffs = self.ffs_factory()
         content_expected = b"content"
         hash_expected = hashlib.sha256(content_expected).hexdigest()
-        meta_expected = {}
+        meta_expected: Dict[str, str] = {"meta_key": "meta_value"}
 
         with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
             file.write(content_expected)
 
         with open(
-            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"),
+            "w",
+            encoding="utf-8",
         ) as file:
             json.dump(meta_expected, file)
 
@@ -83,13 +88,15 @@ def test_delete(self) -> None:
         ffs: Ffs = self.ffs_factory()
         content_expected = b"content"
         hash_expected = hashlib.sha256(content_expected).hexdigest()
-        meta_expected = {}
+        meta_expected: Dict[str, str] = {"meta_key": "meta_value"}
 
         with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
             file.write(content_expected)
 
         with open(
-            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"),
+            "w",
+            encoding="utf-8",
         ) as file:
             json.dump(meta_expected, file)
 
@@ -105,13 +112,15 @@ def test_list(self) -> None:
         ffs: Ffs = self.ffs_factory()
         content_expected = b"content"
         hash_expected = hashlib.sha256(content_expected).hexdigest()
-        meta_expected = {}
+        meta_expected: Dict[str, str] = {"meta_key": "meta_value"}
 
         with open(os.path.join(self.tmp_dir.name, hash_expected), "wb") as file:
             file.write(content_expected)
 
         with open(
-            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"), "w"
+            os.path.join(self.tmp_dir.name, f"{hash_expected}.META"),
+            "w",
+            encoding="utf-8",
         ) as file:
             json.dump(meta_expected, file)
 

From adeeb3ceff6a2589d1e108bee6da5a1213f8764d Mon Sep 17 00:00:00 2001
From: Taner Topal <taner@flower.ai>
Date: Mon, 17 Jun 2024 00:05:42 +0200
Subject: [PATCH 04/17] Fix

---
 src/py/flwr/server/superlink/ffs/ffs_test.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/py/flwr/server/superlink/ffs/ffs_test.py b/src/py/flwr/server/superlink/ffs/ffs_test.py
index 3baacbe0489..3b25ac7b206 100644
--- a/src/py/flwr/server/superlink/ffs/ffs_test.py
+++ b/src/py/flwr/server/superlink/ffs/ffs_test.py
@@ -55,7 +55,9 @@ def test_put(self) -> None:
         assert hash_actual == hash_expected
 
         # Check if file was created
-        assert [hash_expected, f"{hash_expected}.META"] == os.listdir(self.tmp_dir.name)
+        assert {hash_expected, f"{hash_expected}.META"} == set(
+            os.listdir(self.tmp_dir.name)
+        )
 
     def test_get(self) -> None:
         """Test if object can be retrieved."""
@@ -104,7 +106,7 @@ def test_delete(self) -> None:
         ffs.delete(hash_expected)
 
         # Assert
-        assert [] == os.listdir(self.tmp_dir.name)
+        assert set() == set(os.listdir(self.tmp_dir.name))
 
     def test_list(self) -> None:
         """Test if object hashes can be listed."""
@@ -128,7 +130,7 @@ def test_list(self) -> None:
         hashes = ffs.list()
 
         # Assert
-        assert [hash_expected] == hashes
+        assert {hash_expected} == set(hashes)
 
 
 class DiskFfsTest(FfsTest, unittest.TestCase):

From ab76f278a9a652b64c73f5bb4829f104784692d6 Mon Sep 17 00:00:00 2001
From: Charles Beauville <charles@flower.ai>
Date: Fri, 19 Jul 2024 11:48:38 +0200
Subject: [PATCH 05/17] Fix docstring

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index aab5ba3d424..6b1d8151c0c 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -49,7 +49,7 @@ def __init__(self, base_dir: str) -> None:
         self.base_dir = base_dir
 
     def put(self, content: bytes, meta: Dict[str, str]) -> str:
-        """Store bytes and metadata. Return sha256hex hash of data as str.
+        """Store bytes and metadata and returns sha256hex hash of data as str.
 
         Parameters
         ----------

From d565c87822a1f62e62d58cfb27bf03687fd411b9 Mon Sep 17 00:00:00 2001
From: Charles Beauville <charles@flower.ai>
Date: Fri, 19 Jul 2024 12:18:35 +0200
Subject: [PATCH 06/17] Sort _all_

---
 src/py/flwr/server/superlink/ffs/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/py/flwr/server/superlink/ffs/__init__.py b/src/py/flwr/server/superlink/ffs/__init__.py
index 4b2ee7a2e2a..0273d2a630e 100644
--- a/src/py/flwr/server/superlink/ffs/__init__.py
+++ b/src/py/flwr/server/superlink/ffs/__init__.py
@@ -19,6 +19,6 @@
 from .ffs import Ffs as Ffs
 
 __all__ = [
-    "Ffs",
     "DiskFfs",
+    "Ffs",
 ]

From 4345891eeed1361c7c799f56e691a6b638fa4520 Mon Sep 17 00:00:00 2001
From: Charles Beauville <charles@flower.ai>
Date: Fri, 19 Jul 2024 17:15:56 +0200
Subject: [PATCH 07/17] Use Pathlib instead of os.path

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 35 +++++---------------
 1 file changed, 9 insertions(+), 26 deletions(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index 6b1d8151c0c..b8893f14fd8 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -16,25 +16,12 @@
 
 import hashlib
 import json
-import os
+from pathlib import Path
 from typing import Dict, List, Tuple
 
 from flwr.server.superlink.ffs.ffs import Ffs
 
 
-def write_dict_to_file(data_dict: Dict[str, str], file_path: str) -> None:
-    """Write a Dict to a file in JSON format."""
-    with open(file_path, "w", encoding="utf-8") as file:
-        json.dump(data_dict, file)
-
-
-def read_dict_from_file(file_path: str) -> Dict[str, str]:
-    """Read a Dict from a JSON file."""
-    with open(file_path, encoding="utf-8") as file:
-        data_dict: Dict[str, str] = json.load(file)
-    return data_dict
-
-
 class DiskFfs(Ffs):  # pylint: disable=R0904
     """Disk based Flower File Storage interface for large objects."""
 
@@ -46,7 +33,7 @@ def __init__(self, base_dir: str) -> None:
         base_dir : string
             The base directory to store the objects.
         """
-        self.base_dir = base_dir
+        self.base_dir = Path(base_dir)
 
     def put(self, content: bytes, meta: Dict[str, str]) -> str:
         """Store bytes and metadata and returns sha256hex hash of data as str.
@@ -65,10 +52,8 @@ def put(self, content: bytes, meta: Dict[str, str]) -> str:
         """
         content_hash = hashlib.sha256(content).hexdigest()
 
-        with open(os.path.join(self.base_dir, content_hash), "wb") as file:
-            file.write(content)
-
-        write_dict_to_file(meta, os.path.join(self.base_dir, f"{content_hash}.META"))
+        (self.base_dir / content_hash).write_bytes(content)
+        (self.base_dir / f"{content_hash}.META").write_text(json.dumps(meta))
 
         return content_hash
 
@@ -85,10 +70,8 @@ def get(self, key: str) -> Tuple[bytes, Dict[str, str]]:
         Tuple[bytes, Dict[str, str]]
             A tuple containing the object and it's metadata.
         """
-        with open(os.path.join(self.base_dir, key), "rb") as file:
-            content = file.read()
-
-        meta = read_dict_from_file(os.path.join(self.base_dir, f"{key}.META"))
+        content = (self.base_dir / key).read_bytes()
+        meta = json.loads((self.base_dir / f"{key}.META").read_text())
 
         return content, meta
 
@@ -100,8 +83,8 @@ def delete(self, key: str) -> None:
         hash : string
             The sha256hex hash of the object to be deleted.
         """
-        os.remove(os.path.join(self.base_dir, key))
-        os.remove(os.path.join(self.base_dir, f"{key}.META"))
+        (self.base_dir / key).unlink()
+        (self.base_dir / f"{key}.META").unlink()
 
     def list(self) -> List[str]:
         """List all keys.
@@ -115,5 +98,5 @@ def list(self) -> List[str]:
             A list of all keys.
         """
         return [
-            item for item in os.listdir(self.base_dir) if not item.endswith(".META")
+            item.name for item in self.base_dir.iterdir() if not item.suffix == ".META"
         ]

From d570b262a6a92477e20219c9d3718adf079dc231 Mon Sep 17 00:00:00 2001
From: Charles Beauville <charles@flower.ai>
Date: Tue, 30 Jul 2024 20:54:56 +0200
Subject: [PATCH 08/17] Add makedir

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py  |  1 +
 src/py/flwr/server/superlink/ffs/ffs.py       |  2 +-
 .../flwr/server/superlink/ffs/ffs_factory.py  | 45 +++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 src/py/flwr/server/superlink/ffs/ffs_factory.py

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index b8893f14fd8..d113499e702 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -54,6 +54,7 @@ def put(self, content: bytes, meta: Dict[str, str]) -> str:
 
         (self.base_dir / content_hash).write_bytes(content)
         (self.base_dir / f"{content_hash}.META").write_text(json.dumps(meta))
+        os.makedirs(self.base_dir, exist_ok=True)
 
         return content_hash
 
diff --git a/src/py/flwr/server/superlink/ffs/ffs.py b/src/py/flwr/server/superlink/ffs/ffs.py
index d114cee0f0c..eab1cb5bf22 100644
--- a/src/py/flwr/server/superlink/ffs/ffs.py
+++ b/src/py/flwr/server/superlink/ffs/ffs.py
@@ -24,7 +24,7 @@ class Ffs(abc.ABC):  # pylint: disable=R0904
 
     @abc.abstractmethod
     def put(self, content: bytes, meta: Dict[str, str]) -> str:
-        """Store bytes and metadata. Return sha256hex hash of data as str.
+        """Store bytes and metadata and return sha256hex hash of data as str.
 
         Parameters
         ----------
diff --git a/src/py/flwr/server/superlink/ffs/ffs_factory.py b/src/py/flwr/server/superlink/ffs/ffs_factory.py
new file mode 100644
index 00000000000..fed078a6c5c
--- /dev/null
+++ b/src/py/flwr/server/superlink/ffs/ffs_factory.py
@@ -0,0 +1,45 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Factory class that creates Ffs instances."""
+
+
+from logging import DEBUG
+from typing import Optional
+
+from flwr.common.logger import log
+
+from .disk_ffs import DiskFfs
+from .ffs import Ffs
+
+
+class FfsFactory:
+    """Factory class that creates Ffs instances.
+
+    Parameters
+    ----------
+    base_dir : str
+        The base directory to store the objects.
+    """
+
+    def __init__(self, base_dir: str) -> None:
+        self.base_dir = base_dir
+        self.ffs_instance: Optional[Ffs] = None
+
+    def ffs(self) -> Ffs:
+        """Return a Ffs instance and create it, if necessary."""
+        # SqliteState
+        ffs = DiskFfs(self.base_dir)
+        log(DEBUG, "Using Disk Flower File System")
+        return ffs

From 8c213f07de69a623a4c1fe48eb05c142fb434c61 Mon Sep 17 00:00:00 2001
From: Charles Beauville <charles@flower.ai>
Date: Tue, 30 Jul 2024 20:55:28 +0200
Subject: [PATCH 09/17] Fix makedir

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index d113499e702..0bbb798d271 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -52,9 +52,9 @@ def put(self, content: bytes, meta: Dict[str, str]) -> str:
         """
         content_hash = hashlib.sha256(content).hexdigest()
 
+        self.base_dir.mkdir(exist_ok=True, parents=True)
         (self.base_dir / content_hash).write_bytes(content)
         (self.base_dir / f"{content_hash}.META").write_text(json.dumps(meta))
-        os.makedirs(self.base_dir, exist_ok=True)
 
         return content_hash
 

From 8264956793acacbd0f045e0fe9a3512ad03ed5f1 Mon Sep 17 00:00:00 2001
From: Charles Beauville <charles@flower.ai>
Date: Sun, 11 Aug 2024 21:49:51 +0200
Subject: [PATCH 10/17] Fix ffs

---
 src/py/flwr/server/superlink/ffs/ffs.py | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/py/flwr/server/superlink/ffs/ffs.py b/src/py/flwr/server/superlink/ffs/ffs.py
index eab1cb5bf22..37df62167ae 100644
--- a/src/py/flwr/server/superlink/ffs/ffs.py
+++ b/src/py/flwr/server/superlink/ffs/ffs.py
@@ -35,23 +35,23 @@ def put(self, content: bytes, meta: Dict[str, str]) -> str:
 
         Returns
         -------
-        sha256hex : string
-            The sha256hex hash of the content.
+        str
+            The key (sha256hex hash) of the content.
         """
 
     @abc.abstractmethod
     def get(self, key: str) -> Tuple[bytes, Dict[str, str]]:
-        """Return tuple containing the object and it's meta fields.
+        """Return tuple containing the object content and metadata.
 
         Parameters
         ----------
-        hash : string
-            The sha256hex hash of the object to be retrieved.
+        key : str
+            The key (sha256hex hash) of the object to be retrieved.
 
         Returns
         -------
         Tuple[bytes, Dict[str, str]]
-            A tuple containing the object and it's metadata.
+            A tuple containing the object content and metadata.
         """
 
     @abc.abstractmethod
@@ -60,19 +60,20 @@ def delete(self, key: str) -> None:
 
         Parameters
         ----------
-        hash : string
-            The sha256hex hash of the object to be deleted.
+        key : str
+            The key (sha256hex hash) of the object to be deleted.
         """
 
     @abc.abstractmethod
     def list(self) -> List[str]:
-        """List all keys.
+        """List keys of all stored objects.
 
-        Can be used to list all keys in the storage and e.g. to clean up
-        the storage with the delete method.
+        Return all available keys in this `Ffs` instance.
+        This can be combined with, for example,
+        the `delete` method to delete objects.
 
         Returns
         -------
         List[str]
-            A list of all keys.
+            A list of all available keys.
         """

From fa8ab39e6037ac53fbffa79d8a0602a72f70a5ae Mon Sep 17 00:00:00 2001
From: Charles Beauville <charles@flower.ai>
Date: Sun, 11 Aug 2024 21:52:23 +0200
Subject: [PATCH 11/17] Improve docstrings

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index 0bbb798d271..85103dce91d 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -30,7 +30,7 @@ def __init__(self, base_dir: str) -> None:
 
         Parameters
         ----------
-        base_dir : string
+        base_dir : str
             The base directory to store the objects.
         """
         self.base_dir = Path(base_dir)
@@ -47,8 +47,8 @@ def put(self, content: bytes, meta: Dict[str, str]) -> str:
 
         Returns
         -------
-        sha256hex : string
-            The sha256hex hash of the content.
+        str
+            The key (sha256hex hash) of the content.
         """
         content_hash = hashlib.sha256(content).hexdigest()
 
@@ -59,17 +59,17 @@ def put(self, content: bytes, meta: Dict[str, str]) -> str:
         return content_hash
 
     def get(self, key: str) -> Tuple[bytes, Dict[str, str]]:
-        """Return tuple containing the object and it's meta fields.
+        """Return tuple containing the object content and metadata.
 
         Parameters
         ----------
-        hash : string
+        key : str
             The sha256hex hash of the object to be retrieved.
 
         Returns
         -------
         Tuple[bytes, Dict[str, str]]
-            A tuple containing the object and it's metadata.
+            A tuple containing the object content and metadata.
         """
         content = (self.base_dir / key).read_bytes()
         meta = json.loads((self.base_dir / f"{key}.META").read_text())
@@ -81,7 +81,7 @@ def delete(self, key: str) -> None:
 
         Parameters
         ----------
-        hash : string
+        key : str
             The sha256hex hash of the object to be deleted.
         """
         (self.base_dir / key).unlink()
@@ -96,7 +96,7 @@ def list(self) -> List[str]:
         Returns
         -------
         List[str]
-            A list of all keys.
+            A list of all available keys.
         """
         return [
             item.name for item in self.base_dir.iterdir() if not item.suffix == ".META"

From 04e89dca065f5afb44222c8fe38d01ba3332336c Mon Sep 17 00:00:00 2001
From: "Daniel J. Beutel" <daniel@flower.ai>
Date: Mon, 12 Aug 2024 22:26:01 +0200
Subject: [PATCH 12/17] Update src/py/flwr/server/superlink/ffs/disk_ffs.py

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index 85103dce91d..908994bf634 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -23,7 +23,7 @@
 
 
 class DiskFfs(Ffs):  # pylint: disable=R0904
-    """Disk based Flower File Storage interface for large objects."""
+    """Disk-based Flower File Storage interface for large objects."""
 
     def __init__(self, base_dir: str) -> None:
         """Create a new DiskFfs instance.

From 24ddd6dd04a64206d936619192bd5afe9681369a Mon Sep 17 00:00:00 2001
From: Charles Beauville <charles@flower.ai>
Date: Mon, 12 Aug 2024 22:26:01 +0200
Subject: [PATCH 13/17] Remove ffs factory

---
 .../flwr/server/superlink/ffs/ffs_factory.py  | 45 -------------------
 1 file changed, 45 deletions(-)
 delete mode 100644 src/py/flwr/server/superlink/ffs/ffs_factory.py

diff --git a/src/py/flwr/server/superlink/ffs/ffs_factory.py b/src/py/flwr/server/superlink/ffs/ffs_factory.py
deleted file mode 100644
index fed078a6c5c..00000000000
--- a/src/py/flwr/server/superlink/ffs/ffs_factory.py
+++ /dev/null
@@ -1,45 +0,0 @@
-# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-# ==============================================================================
-"""Factory class that creates Ffs instances."""
-
-
-from logging import DEBUG
-from typing import Optional
-
-from flwr.common.logger import log
-
-from .disk_ffs import DiskFfs
-from .ffs import Ffs
-
-
-class FfsFactory:
-    """Factory class that creates Ffs instances.
-
-    Parameters
-    ----------
-    base_dir : str
-        The base directory to store the objects.
-    """
-
-    def __init__(self, base_dir: str) -> None:
-        self.base_dir = base_dir
-        self.ffs_instance: Optional[Ffs] = None
-
-    def ffs(self) -> Ffs:
-        """Return a Ffs instance and create it, if necessary."""
-        # SqliteState
-        ffs = DiskFfs(self.base_dir)
-        log(DEBUG, "Using Disk Flower File System")
-        return ffs

From 35c2bd1f0e1d8c4a1ddd0621cebccd8675010711 Mon Sep 17 00:00:00 2001
From: "Daniel J. Beutel" <daniel@flower.ai>
Date: Mon, 12 Aug 2024 22:37:47 +0200
Subject: [PATCH 14/17] Update src/py/flwr/server/superlink/ffs/disk_ffs.py

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index 908994bf634..9dac1737638 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -47,7 +47,7 @@ def put(self, content: bytes, meta: Dict[str, str]) -> str:
 
         Returns
         -------
-        str
+        key : str
             The key (sha256hex hash) of the content.
         """
         content_hash = hashlib.sha256(content).hexdigest()

From 8ef14fb1ad4a35f2a3e95e19f473fe425aaff4c8 Mon Sep 17 00:00:00 2001
From: "Daniel J. Beutel" <daniel@flower.ai>
Date: Mon, 12 Aug 2024 22:39:06 +0200
Subject: [PATCH 15/17] Update src/py/flwr/server/superlink/ffs/disk_ffs.py

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index 9dac1737638..b0a78afad15 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -36,7 +36,7 @@ def __init__(self, base_dir: str) -> None:
         self.base_dir = Path(base_dir)
 
     def put(self, content: bytes, meta: Dict[str, str]) -> str:
-        """Store bytes and metadata and returns sha256hex hash of data as str.
+        """Store bytes and metadata and return key (hash of content).
 
         Parameters
         ----------

From 5fe921cc183810e7f3d5d0c1924263a0a908c9fc Mon Sep 17 00:00:00 2001
From: "Daniel J. Beutel" <daniel@flower.ai>
Date: Mon, 12 Aug 2024 22:43:53 +0200
Subject: [PATCH 16/17] Update src/py/flwr/server/superlink/ffs/ffs.py

---
 src/py/flwr/server/superlink/ffs/ffs.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/py/flwr/server/superlink/ffs/ffs.py b/src/py/flwr/server/superlink/ffs/ffs.py
index 37df62167ae..622988141c9 100644
--- a/src/py/flwr/server/superlink/ffs/ffs.py
+++ b/src/py/flwr/server/superlink/ffs/ffs.py
@@ -35,7 +35,7 @@ def put(self, content: bytes, meta: Dict[str, str]) -> str:
 
         Returns
         -------
-        str
+        key : str
             The key (sha256hex hash) of the content.
         """
 

From 61854645ff9d1fbfca3085adf549b516544dca5a Mon Sep 17 00:00:00 2001
From: "Daniel J. Beutel" <daniel@flower.ai>
Date: Mon, 12 Aug 2024 22:44:49 +0200
Subject: [PATCH 17/17] Update src/py/flwr/server/superlink/ffs/disk_ffs.py

---
 src/py/flwr/server/superlink/ffs/disk_ffs.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/py/flwr/server/superlink/ffs/disk_ffs.py b/src/py/flwr/server/superlink/ffs/disk_ffs.py
index b0a78afad15..5331af50046 100644
--- a/src/py/flwr/server/superlink/ffs/disk_ffs.py
+++ b/src/py/flwr/server/superlink/ffs/disk_ffs.py
@@ -90,8 +90,9 @@ def delete(self, key: str) -> None:
     def list(self) -> List[str]:
         """List all keys.
 
-        Can be used to list all keys in the storage and e.g. to clean up
-        the storage with the delete method.
+        Return all available keys in this `Ffs` instance.
+        This can be combined with, for example,
+        the `delete` method to delete objects.
 
         Returns
         -------