Arvados

Reviewing 3825-crunch-pipe-to-arv-put at c6a6231

• I think it would read better if output_log_* were renamed to log_writer_*
  • The word "output" usually means "output of a task or job" around here, and that's already a bit overloaded and confusing.
  • Perhaps write_output_log should rename to something slightly different than write_log_writer, though. Maybe write_to_log_writer or log_writer_send?
  • I do like the idea of using the whole substring log_writer (née output_log) in all of the related functions. It makes a really clear distinction between "this log pipe" and "some mysterious perl feature" and "some other logging-related thing we do here" etc.

I think a semicolon, although not strictly necessary, would be better form here:

• +sub output_log_is_active() {
  +  return $log_pipe_pid
  +}
  

Other than that, LGTM!