add an early return to not connect to the servers if there is nothing…

… to write or delete

lib/paperclip/storage/ftp.rb

@@ -35,16 +35,18 @@ def to_file(style_name = default_style)
       end
 
       def flush_writes
-        with_ftp_servers do |servers|
-          servers.map do |server|
-            Thread.new do
-              @queued_for_write.each do |style_name, file|
-                remote_path = path(style_name)
-                log("saving ftp://#{server.user}@#{server.host}:#{remote_path}")
-                server.put_file(file.path, remote_path)
+        unless @queued_for_write.empty?
+          with_ftp_servers do |servers|
+            servers.map do |server|
+              Thread.new do
+                @queued_for_write.each do |style_name, file|
+                  remote_path = path(style_name)
+                  log("saving ftp://#{server.user}@#{server.host}:#{remote_path}")
+                  server.put_file(file.path, remote_path)
+                end
               end
-            end
-          end.each(&:join)
+            end.each(&:join)
+          end
         end
 
         after_flush_writes # allows attachment to clean up temp files
@@ -53,18 +55,20 @@ def flush_writes
       end
 
       def flush_deletes
-        with_ftp_servers do |servers|
-          servers.map do |server|
-            Thread.new do
-              @queued_for_delete.each do |path|
-                log("deleting ftp://#{server.user}@#{server.host}:#{path}")
-                server.delete_file(path)
-
-                log("deleting empty parent directories ftp://#{server.user}@#{server.host}:#{path}")
-                server.rmdir_p(File.dirname(path))
+        unless @queued_for_delete.empty?
+          with_ftp_servers do |servers|
+            servers.map do |server|
+              Thread.new do
+                @queued_for_delete.each do |path|
+                  log("deleting ftp://#{server.user}@#{server.host}:#{path}")
+                  server.delete_file(path)
+
+                  log("deleting empty parent directories ftp://#{server.user}@#{server.host}:#{path}")
+                  server.rmdir_p(File.dirname(path))
+                end
               end
-            end
-          end.each(&:join)
+            end.each(&:join)
+          end
         end
 
         @queued_for_delete = []

spec/paperclip/storage/ftp_spec.rb

@@ -80,6 +80,17 @@
   end
 
   context "#flush_writes" do
+    it "doesn't connect to the servers if there is nothing to write" do
+      attachment.instance_variable_set(:@queued_for_write, {})
+
+      attachment.should_not_receive(:with_ftp_servers)
+      attachment.should_receive(:after_flush_writes).with(no_args)
+
+      attachment.flush_writes
+
+      attachment.queued_for_write.should == {}
+    end
+
     it "stores the files on every server" do
       original_file = double("original_file", :path => "/tmp/original/foo.jpg")
       thumb_file    = double("thumb_file",    :path => "/tmp/thumb/foo.jpg")
@@ -105,6 +116,16 @@
   end
 
   context "#flush_deletes" do
+    it "doesn't connect to the servers if there is nothing to delete" do
+      attachment.instance_variable_set(:@queued_for_delete, [])
+
+      attachment.should_not_receive(:with_ftp_servers)
+
+      attachment.flush_deletes
+
+      attachment.instance_variable_get(:@queued_for_delete).should == []
+    end
+
     it "deletes the files on every server" do
       attachment.instance_variable_set(:@queued_for_delete, [
         "/files/original/foo.jpg",