Add S3OptimizedUploadStorage (#128)

README.rst

@@ -195,3 +195,23 @@ uploaded to AWS S3 directly and not to your Django application server.
    :target: https://codecov.io/gh/codingjoe/django-s3file
 .. |GitHub license| image:: https://img.shields.io/badge/license-MIT-blue.svg
    :target: https://raw.githubusercontent.com/codingjoe/django-s3file/master/LICENSE
+
+Using optimized S3Boto3Storage
+------------------------------
+
+Since ``S3Boto3Storage`` supports storing data from any other fileobj, 
+it uses a generalized ``_save`` function. This leads to the frontend uploading 
+the file to S3 and then copying it byte-by-byte to perform a move operation just 
+to rename the uploaded object. For large files this leads to additional loading 
+times for the user. 
+
+That's why S3File provides an optimized version of this method at 
+``storages_optimized.S3OptimizedUploadStorage``. It uses the more efficient 
+``copy`` method from S3, given that we know that we only copy from one S3 location to another.
+
+.. code:: python
+
+    from s3file.storages_optimized import S3OptimizedUploadStorage
+
+    class MyStorage(S3OptimizedUploadStorage):  # Subclass and use like any other storage
+        default_acl = 'private'

s3file/storages_optimized.py

@@ -0,0 +1,43 @@
+from storages.backends.s3boto3 import S3Boto3Storage
+
+
+class S3OptimizedUploadStorage(S3Boto3Storage):
+    """
+    Class for an optimized S3 storage.
+
+    This storage prevents unnecessary operation to copy with the general ``upload_fileobj``
+    command when the object already is a S3 object where the faster copy command can be used.
+
+    The assumption is that ``content`` contains a S3 object from which we can copy.
+
+    See also discussion here: https://github.com/codingjoe/django-s3file/discussions/126
+    """
+
+    def _save(self, name, content):
+        # Basically copy the implementation of _save of S3Boto3Storage
+        # and replace the obj.upload_fileobj with a copy function
+        cleaned_name = self._clean_name(name)
+        name = self._normalize_name(cleaned_name)
+        params = self._get_write_parameters(name, content)
+
+        if (
+            self.gzip
+            and params["ContentType"] in self.gzip_content_types
+            and "ContentEncoding" not in params
+        ):
+            content = self._compress_content(content)
+            params["ContentEncoding"] = "gzip"
+
+        obj = self.bucket.Object(name)
+        # content.seek(0, os.SEEK_SET)  # Disable unnecessary seek operation
+        # obj.upload_fileobj(content, ExtraArgs=params)  # Disable upload function
+
+        if not hasattr(content, "obj") or not hasattr(content.obj, "key"):
+            raise TypeError(
+                "The content object must be a S3 object and contain a valid key."
+            )
+
+        # Copy the file instead uf uploading
+        obj.copy({"Bucket": self.bucket.name, "Key": content.obj.key}, ExtraArgs=params)
+
+        return cleaned_name

tests/test_storages.py

@@ -0,0 +1,76 @@
+import pytest
+from django.core.files.base import ContentFile
+
+from s3file.storages_optimized import S3OptimizedUploadStorage
+
+
+class S3OptimizedMockStorage(S3OptimizedUploadStorage):
+    created_objects = {}
+
+    def _compress_content(self, content):
+        return content
+
+    class bucket:
+        name = "test-bucket"
+
+        class Object:
+            def __init__(self, key):
+                self.key = key
+                self.copy_from_bucket = None
+                self.copy_from_key = None
+                S3OptimizedMockStorage.created_objects[self.key] = self
+
+            def copy(self, s3_object, ExtraArgs):
+                self.copy_from_bucket = s3_object["Bucket"]
+                self.copy_from_key = s3_object["Key"]
+
+
+class TestStorages:
+    url = "/__s3_mock__/"
+
+    def test_post__save_optimized(self):
+        storage = S3OptimizedMockStorage()
+        obj = storage.bucket.Object("tmp/s3file/s3_file.txt")
+
+        class Content:
+            def __init__(self, obj):
+                self.obj = obj
+
+        content = Content(obj)
+        key = storage._save("tmp/s3file/s3_file_copied.txt", content)
+        stored_object = storage.created_objects[
+            "custom/location/tmp/s3file/s3_file_copied.txt"
+        ]
+
+        assert key == "tmp/s3file/s3_file_copied.txt"
+        assert stored_object.copy_from_bucket == storage.bucket.name
+        assert stored_object.copy_from_key == "tmp/s3file/s3_file.txt"
+
+    def test_post__save_optimized_gzip(self):
+        storage = S3OptimizedMockStorage()
+        obj = storage.bucket.Object("tmp/s3file/s3_file.css")
+        storage.gzip = True
+
+        class Content:
+            def __init__(self, obj):
+                self.obj = obj
+
+        content = Content(obj)
+        key = storage._save("tmp/s3file/s3_file_copied.css", content)
+        stored_object = storage.created_objects[
+            "custom/location/tmp/s3file/s3_file_copied.css"
+        ]
+
+        assert key == "tmp/s3file/s3_file_copied.css"
+        assert stored_object.copy_from_bucket == storage.bucket.name
+        assert stored_object.copy_from_key == "tmp/s3file/s3_file.css"
+
+    def test_post__save_optimized_fail(self):
+        storage = S3OptimizedMockStorage()
+
+        with pytest.raises(TypeError) as excinfo:
+            storage._save("tmp/s3file/s3_file_copied.txt", ContentFile(b"s3file"))
+
+        assert "The content object must be a S3 object and contain a valid key." in str(
+            excinfo.value
+        )