Compute checksum and byte_size client side

Then we can add integrity checks on uploads to prevent errors in
transport.

1 files changed, 15 insertions, 3 deletions

diff --git a/lib/active_storage/blob.rb b/lib/active_storage/blob.rb
index 4ce344e2a1..b10dc2c771 100644
--- a/lib/active_storage/blob.rb
+++ b/lib/active_storage/blob.rb
@@ -42,10 +42,10 @@ class ActiveStorage::Blob < ActiveRecord::Base
 
 
   def upload(io)
-    service.upload(key, io)
+    self.checksum  = compute_checksum_in_chunks(io)
+    self.byte_size = io.size
 
-    self.checksum  = service.checksum(key)
-    self.byte_size = service.byte_size(key)
+    service.upload(key, io)
   end
 
   def download
@@ -65,4 +65,16 @@ class ActiveStorage::Blob < ActiveRecord::Base
   def purge_later
     ActiveStorage::PurgeJob.perform_later(self)
   end
+
+
+  private
+    def compute_checksum_in_chunks(io)
+      Digest::MD5.new.tap do |checksum|
+        while chunk = io.read(5.megabytes)
+          checksum << chunk
+        end
+
+        io.rewind
+      end.base64digest
+    end
 end