Rather than teaching only one operation, like 'git fetch', how to write
down throughput to traces, we can learn about a wide range of user
operations that may seem slow by adding tooling to the progress library
itself. Operations which display progress are likely to be slow-running
and the kind of thing we want to monitor for performance anyways. By
showing object counts and data transfer size, we should be able to
make some derived measurements to ensure operations are scaling the way
we expect.
Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
'progress.c' has seen a few fixes recently [1], and, unfortunately,
some of those fixes required further fixes [2]. It seems it's time to
have a few tests focusing on the subtleties of the progress display.
Add the 'test-tool progress' subcommand to help testing the progress
display, reading instructions from standard input and turning them
into calls to the display_progress() and display_throughput()
functions with the given parameters.
The progress display is, however, critically dependent on timing,
because it's only updated once every second or, if the toal is known
in advance, every 1%, and there is the throughput rate as well. These
make the progress display far too undeterministic for testing as-is.
To address this, add a few testing-specific variables and functions to
'progress.c', allowing the the new test helper to:
- Disable the triggered-every-second SIGALRM and set the
'progress_update' flag explicitly based in the input instructions.
This way the progress line will be updated deterministically when
the test wants it to be updated.
- Specify the time elapsed since start_progress() to make the
throughput rate calculations deterministic.
Add the new test script 't0500-progress-display.sh' to check a few
simple cases with and without throughput, and that a shorter progress
line properly covers up the previously displayed line in different
situations.
[1] See commits 545dc345eb (progress: break too long progress bar
lines, 2019-04-12) and 9f1fd84e15 (progress: clear previous
progress update dynamically, 2019-04-12).
[2] 1aed1a5f25 (progress: avoid empty line when breaking the progress
line, 2019-05-19)
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
