1 files changed, 28 insertions, 4 deletions
diff --git a/activestorage/lib/active_storage/service/s3_service.rb b/activestorage/lib/active_storage/service/s3_service.rb
index c7e4ec96a2..e4bd57048a 100644
--- a/activestorage/lib/active_storage/service/s3_service.rb
+++ b/activestorage/lib/active_storage/service/s3_service.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+gem "aws-sdk-s3", "~> 1.14"
+
 require "aws-sdk-s3"
 require "active_support/core_ext/numeric/bytes"
 
@@ -7,20 +9,24 @@ module ActiveStorage
   # Wraps the Amazon Simple Storage Service (S3) as an Active Storage service.
   # See ActiveStorage::Service for the generic API documentation that applies to all services.
   class Service::S3Service < Service
-    attr_reader :client, :bucket, :upload_options
+    attr_reader :client, :bucket
+    attr_reader :multipart_upload_threshold, :upload_options
 
     def initialize(bucket:, upload: {}, **options)
       @client = Aws::S3::Resource.new(**options)
       @bucket = @client.bucket(bucket)
 
+      @multipart_upload_threshold = upload.fetch(:multipart_threshold, 100.megabytes)
       @upload_options = upload
     end
 
     def upload(key, io, checksum: nil, content_type: nil, **)
       instrument :upload, key: key, checksum: checksum do
-        object_for(key).put(upload_options.merge(body: io, content_md5: checksum, content_type: content_type))
-      rescue Aws::S3::Errors::BadDigest
-        raise ActiveStorage::IntegrityError
+        if io.size < multipart_upload_threshold
+          upload_with_single_part key, io, checksum: checksum, content_type: content_type
+        else
+          upload_with_multipart key, io, content_type: content_type
+        end
       end
     end
 
@@ -94,6 +100,24 @@ module ActiveStorage
     end
 
     private
+      MAXIMUM_UPLOAD_PARTS_COUNT = 10000
+      MINIMUM_UPLOAD_PART_SIZE   = 5.megabytes
+
+      def upload_with_single_part(key, io, checksum: nil, content_type: nil)
+        object_for(key).put(body: io, content_md5: checksum, content_type: content_type, **upload_options)
+      rescue Aws::S3::Errors::BadDigest
+        raise ActiveStorage::IntegrityError
+      end
+
+      def upload_with_multipart(key, io, content_type: nil)
+        part_size = [ io.size.fdiv(MAXIMUM_UPLOAD_PARTS_COUNT).ceil, MINIMUM_UPLOAD_PART_SIZE ].max
+
+        object_for(key).upload_stream(content_type: content_type, part_size: part_size, **upload_options) do |out|
+          IO.copy_stream(io, out)
+        end
+      end
+
+
       def object_for(key)
         bucket.object(key)
       end