Patch for buffer_size metric reset.

buffer_size.patch

diff --git a/internal/models/running_output.go b/internal/models/running_output.go
index 8d7d9854..97989a14 100644
--- a/internal/models/running_output.go
+++ b/internal/models/running_output.go
@@ -186,6 +186,10 @@ func (ro *RunningOutput) Write() error {
                }
                ro.buffer.Accept(batch)
        }
+       
+       nBuffer = ro.buffer.Len()
+       ro.BufferSize.Set(int64(nBuffer))
+
        return nil 
 }