Use #slice instead of #slice!

lib/fluent/compat/socket_util.rb

@@ -82,7 +82,7 @@ def on_read(data)
             @callback.call(msg, @addr)
             pos = i + @delimiter.length
           end
-          @buffer.slice!(0, pos) if pos > 0
+          @buffer = @buffer[pos..] if pos > 0
         rescue => e
           @log.error "unexpected error", error: e
           close

lib/fluent/plugin/in_syslog.rb

@@ -212,7 +212,10 @@ def start_tcp_server(tls: false)
               message_handler(msg, conn)
             end
           end
-          buffer.slice!(0, pos) if pos > 0
+          if pos > 0
+            buffer = buffer[pos..]
+            conn.buffer = buffer
+          end
         end
       end
     end

lib/fluent/plugin/in_tail.rb

@@ -1057,8 +1057,8 @@ def read_lines(lines)
             # See https://github.com/fluent/fluentd/pull/2527
             @buffer.freeze
             slice_position = idx + 1
-            rbuf = @buffer.slice(0, slice_position)
-            @buffer = @buffer.slice(slice_position, @buffer.size - slice_position)
+            rbuf = @buffer[0, slice_position]
+            @buffer = @buffer[slice_position..]
             idx = @buffer.index(@eol)
 
             is_long_line = @max_line_size && (

lib/fluent/plugin/in_tcp.rb

@@ -149,7 +149,10 @@ def start
               router.emit(tag, time, record)
             end
           end
-          buf.slice!(0, pos) if pos > 0
+          if pos > 0
+            buf = buf[pos..]
+            conn.buffer = buf
+          end
           # If the buffer size exceeds the limit here, it means that the next message will definitely exceed the limit.
           # So we should clear the buffer here. Otherwise, it will keep storing useless data until the next delimiter comes.
           if !@message_length_limit.nil? && @message_length_limit < buf.bytesize
@@ -198,7 +201,10 @@ def start
             end
           end
           router.emit_stream(@tag, es)
-          buf.slice!(0, pos) if pos > 0
+          if pos > 0
+            buf = buf[pos..]
+            conn.buffer = buf
+          end
           # If the buffer size exceeds the limit here, it means that the next message will definitely exceed the limit.
           # So we should clear the buffer here. Otherwise, it will keep storing useless data until the next delimiter comes.
           if !@message_length_limit.nil? && @message_length_limit < buf.bytesize

lib/fluent/plugin_helper/server.rb

@@ -780,7 +780,7 @@ def on_writable
               @mutex.synchronize do
                 # Consider write_nonblock with {exception: false} when IO::WaitWritable error happens frequently.
                 written_bytes = @_handler_socket.write_nonblock(@_handler_write_buffer)
-                @_handler_write_buffer.slice!(0, written_bytes)
+                @_handler_write_buffer = @_handler_write_buffer[written_bytes..]
               end
 
               # No need to call `super` in a synchronized context because TLSServer doesn't use the inner buffer(::IO::Buffer) of Coolio::IO.