Only copy large binary files

Summary: If an input to `glean merge` is already larger than the specified max merged file size, it will just copy it to the output. If the input is in json format, then this causes merge to output json which is unexpected. Only perform the copy if the input is in binary format.

Reviewed By: malanka

Differential Revision: D60988559

fbshipit-source-id: a8e1ffbe1d152ace95def3884d1d53896d016bef

glean/tools/gleancli/GleanCLI/Common.hs

@@ -99,6 +99,7 @@ handleOpt = textOption
 data FileFormat
   = JsonFormat
   | BinaryFormat
+  deriving (Eq)
 
 instance Show FileFormat where
   show ff = case ff of

glean/tools/gleancli/GleanCLI/Merge.hs

@@ -160,7 +160,8 @@ instance Plugin MergeCommand where
         loop !n _ (Just set) [] = write (n, Right set)
         loop !n currentSize acc (f : files) = do
           size <- fromIntegral <$> getFileSize f
-          if size > mergeFileSize  -- just copy huge files
+          if size > mergeFileSize && fileFormat == BinaryFormat
+            -- just copy huge binary files
             then do
               write (n, Left f)
               loop (n+1) currentSize acc files