fix: Improve ZstdCompressor implementation

Signed-off-by: ddukbg <[email protected]>

lib/fluent/plugin/out_s3.rb

@@ -632,16 +632,24 @@ def compress(chunk, tmp)
     end
 
     class ZstdCompressor < Compressor
+      def initialize(level = 3)
+        @level = level
+      end
+
       def ext
         'zst'.freeze
       end
-
+    
       def content_type
         'application/x-zst'.freeze
       end
-
+    
       def compress(chunk, tmp)
-        compressed_data = Zstd.compress(chunk.read, level: @level)
+        uncompressed_data = ''
+        chunk.open do |io|
+          uncompressed_data = io.read
+        end
+        compressed_data = Zstd.compress(uncompressed_data, level: @level)
         tmp.write(compressed_data)
       rescue => e
         log.warn "zstd compression failed: #{e.message}"