fix: Improve ZstdCompressor implementation

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

lib/fluent/plugin/out_s3.rb

@@ -632,20 +632,40 @@ def compress(chunk, tmp)
     end
 
     class ZstdCompressor < Compressor
+      require 'zstd-ruby'
+
+      DEFAULT_LEVEL = 3
+
+      def initialize(level = nil)
+        @level = level || DEFAULT_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)
-        tmp.write(compressed_data)
-      rescue => e
-        log.warn "zstd compression failed: #{e.message}"
-        raise e
+        begin
+          original_data = chunk.read
+          log.debug "Original data size: #{original_data.bytesize}"
+
+          compressed = Zstd.compress(original_data, level: @level)
+          log.debug "Compressed data size: #{compressed.bytesize}"
+
+          tmp.binmode
+          bytes_written = tmp.write(compressed)
+          log.debug "Bytes written: #{bytes_written}"
+          tmp.flush
+          tmp.close
+        rescue => e
+          log.warn "zstd compression failed: #{e.message}"
+          log.warn e.backtrace.join("\n")
+          raise e
+        end
       end
     end