Re: [PATCH] reduce progress updates in background

[Luke Mewburn <luke@mewburn.net>]

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On Mon, Apr 13, 2015 at 11:01:04AM -0400, Nicolas Pitre wrote:
  | > That's what happens; the suppression only occurs if the process is
  | > currently background.  If I start a long-running operation (such as "git
  | > fsck"), the progress is displayed. I then suspend & background, and the
  | > progress is suppressed.  If I resume the process in the foreground, the
  | > progress starts to display again at the appropriate point.
  | 
  | I agree. I was just comenting on your suggestion about caching the 
  | in_progress_fd() result which would prevent that.

Ahh.  My suggestion about is_foreground_fd() result caching within
struct progress was only about caching the getpgid(0) portion of the
test (as that's not expected to change for the life of the process), and
not the tcgetpgrp(fd) portion.  I.e, add 'int curpgid' to struct
progress, set that to getpgid(0) in start_progress_display(), and
compare tcgetpgrp(fd) against progress->curpgid.

In any case, I think it's a micro optimisation not worth worrying about
at this point, given is_foreground_fd() is only called each time the
output would change, per your feedback.

regards,
Luke.

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