Re: [PATCH 1/1] fast-import: checkpoint: dump branches/tags/marks even if object_count==0

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 27, 2017, 03:37 UTC
Message-ID: <xmqqefqs7qx8.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <eedb545ccb43a14820802bab10f59ab8ab9557a0.1506419307.git.e@nanocritical.com>

"Eric Rannaud" <e@nanocritical.com> writes:

Show 17 quoted lines

> Any comments on the testing strategy with a background fast-import?
>
> To summarize:
> - fast-import is started in the background with a command stream that
>   ends with "checkpoint\nprogress checkpoint\n". fast-import keeps
>   running after reaching the last command (we don't want fast-import to
>   terminate).
> - In the meantime, the test is waiting to read "progress checkpoint" in
>   the output of fast-import, then it checks the testing conditions.
> - Finally, the test ensures that fast-import is still running in the
>   background (and thus that it has just observed the effect of
>   checkpoint, and not the side effects of fast-import terminating).
> - After 10 sec, no matter what, the background fast-import is sent
>   "done" and terminates.
>
> I tried to make sure that the test runs quickly and does not (typically) sleep.
> Upon failure, the test may take up to 10 sec to fully terminate.

Hmmmm, it certainly looks a bit too brittle with many tweakables like 10, 50, 55, etc. that heavily depend on the load on the system.

Sorry for asking you to go through the hoops.

Show 25 quoted lines

> diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
> index 67b8c50a5ab4..b410bf3a3a7a 100755
> --- a/t/t9300-fast-import.sh
> +++ b/t/t9300-fast-import.sh
> @@ -3120,4 +3120,121 @@ test_expect_success 'U: validate root delete result' '
>  	compare_diff_raw expect actual
>  '
>  
> +###
> +### series V (checkpoint)
> +###
> +
> +# To make sure you're observing the side effects of checkpoint *before*
> +# fast-import terminates (and thus writes out its state), check that the
> +# fast-import process is still running using background_import_still_running
> +# *after* evaluating the test conditions.
> +background_import_until_checkpoint () {
> +	options=$1
> +	input_file=$2
> +	( cat $input_file; sleep 10; echo done ) | git fast-import $options >V.output &
> +	echo $! >V.pid
> +
> +	# The loop will poll for approximately 5 seconds before giving up.
> +	n=0
> +	while ! test "$(cat V.output)" = "progress checkpoint"; do

Micronit. Just like you have if/then on different lines, have while/do on different lines, i.e.

	while test "$(cat V.output)" != "progress checkpoint"
	do

> +		if test $n -gt 55
> +		then
> +...

> +background_import_still_running () {
> +	if ! ps --pid "$(cat V.pid)"

"ps --pid" is probably not portable (I think we'd do "kill -0 $pid" instead in our existing tests---and it should be kosher according to POSIX [*1*, *2*]).

> +test_expect_success 'V: checkpoint updates refs after reset' '
> +	cat >input <<-INPUT_END &&

It is not wrong per-se but we quote INPUT_END when there is no interpolation necessary in the body of here document to help readers, like so:

	cat >input <<-\INPUT_END &&

Show 6 quoted lines

> +	reset refs/heads/V
> +	from refs/heads/U
> +
> +	checkpoint
> +	progress checkpoint
> +	INPUT_END

> +test_expect_success 'V: checkpoint updates refs and marks after commit' '
> +	cat >input <<-INPUT_END &&

This we do want interpolation and the above is correct.

[Footnotes]

*1* http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html 
    lists '0' as an allowed signal number to be sent, and defers to the
    description of the kill() function to explain what happens.

*2* http://pubs.opengroup.org/onlinepubs/9699919799/functions/kill.html
    says """If sig is 0 (the null signal), error checking is
    performed but no signal is actually sent. The null signal can be
    used to check the validity of pid."""