Re: [PATCH 2/5] progress: return early when in the background
On Mon, Mar 25 2019, SZEDER Gábor wrote:
Show 12 quoted lines
> When a git process runs in the background, it doesn't display
> progress, only the final "done" line [1]. The condition to check that
> are a bit too deep in the display() function, and thus it calculates
> the progress percentage even when no progress will be displayed
> anyway.
>
> Restructure the display() function to return early when we are in the
> background, which prevents the unnecessary progress percentae
> calculation, and make the function look a bit better by losing one
> level of indentation.
>
> [1] 85cb8906f0 (progress: no progress in background, 2015-04-13)
CC-ing the author of that patch.
Show 52 quoted lines
> Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
> ---
> progress.c | 26 ++++++++++++++------------
> 1 file changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/progress.c b/progress.c
> index 02a20e7d58..b57c0dae16 100644
> --- a/progress.c
> +++ b/progress.c
> @@ -86,28 +86,30 @@ static void display(struct progress *progress, uint64_t n, const char *done)
> return;
>
> progress->last_value = n;
> +
> + if (!is_foreground_fd(fileno(stderr)) && !done) {
> + progress_update = 0;
> + return;
> + }
> +
> tp = (progress->throughput) ? progress->throughput->display.buf : "";
> eol = done ? done : " \r";
> if (progress->total) {
> unsigned percent = n * 100 / progress->total;
> if (percent != progress->last_percent || progress_update) {
> progress->last_percent = percent;
> - if (is_foreground_fd(fileno(stderr)) || done) {
> - fprintf(stderr, "%s: %3u%% (%"PRIuMAX"/%"PRIuMAX")%s%s",
> - progress->title, percent,
> - (uintmax_t)n, (uintmax_t)progress->total,
> - tp, eol);
> - fflush(stderr);
> - }
> + fprintf(stderr, "%s: %3u%% (%"PRIuMAX"/%"PRIuMAX")%s%s",
> + progress->title, percent,
> + (uintmax_t)n, (uintmax_t)progress->total,
> + tp, eol);
> + fflush(stderr);
> progress_update = 0;
> return;
> }
> } else if (progress_update) {
> - if (is_foreground_fd(fileno(stderr)) || done) {
> - fprintf(stderr, "%s: %"PRIuMAX"%s%s",
> - progress->title, (uintmax_t)n, tp, eol);
> - fflush(stderr);
> - }
> + fprintf(stderr, "%s: %"PRIuMAX"%s%s",
> + progress->title, (uintmax_t)n, tp, eol);
> + fflush(stderr);
> progress_update = 0;
> return;
> }This patch looks good, just notes for potential follow-up:
* Is the "is_foreground_fd(fileno(stderr))" case worth moving into
start_progress_delay() & setting a variable? It's a few C lib calls &
potential syscall (getpid(...)).
* Is that "|| done" part in the "progress_update" case something that
needs to happen? I.e. can we entirely skip the "setup signal handler"
part in start_progress_delay() if we detect that we're not in the
foreground, and then rely on the stop_progress() call to print the
"done"?
Although we set "progress_update = 1" in stop_progress_msg(), so it's
not *just* the signal handler but also us "faking" it, and we'd still
need to stash away "progress->last_value = n" in display() in that
backgrounding case.
So maybe it's as simple as it's going to get.
Ævar Arnfjörð Bjarmason <avarab@gmail.com>