Subject: Re: [PATCH 1/2] t5351: avoid relying on `core.fsyncMethod = batch` to be supported

From: Junio C Hamano <[email-masked]>
Date: Fri, 29 Jul 2022 09:07:46 -0700

"Johannes Schindelin via GitGitGadget" <[email-masked]>
writes:

> From: Johannes Schindelin <[email-masked]>
>
> On FreeBSD, this mode is not supported. But since 3a251bac0d1a (trace2:
> only include "fsync" events if we git_fsync(), 2022-07-18) t5351 will
> fail if this mode is unsupported.
>
> Let's address this in the minimal fashion, by detecting that that mode
> is unsupported and expecting a different count of hardware flushes in
> that case.
>
> This fixes the CI/PR builds on FreeBSD again.
>
> Note: A better way would be to test only what is relevant in t5351.6
> "unpack big object in stream (core.fsyncmethod=batch)" again instead of
> blindly comparing the output against some exact text. But that would
> pretty much revert the idea of above-mentioned commit, and that commit
> was _just_ accepted into Git's main branch so one must assume that it
> was intentional.
>
> Signed-off-by: Johannes Schindelin <[email-masked]>
> ---
>  bulk-checkin.c                  |  2 ++
>  t/t5351-unpack-large-objects.sh | 10 ++++++++--
>  2 files changed, 10 insertions(+), 2 deletions(-)

I am inclined to take this as-is for now.

But it inherits from 3a251bac0d1a the general "we should be able to
count the value" expectation, which may not be the best approach to
run this test; asking Acks from those originally involved in this
area and possibly ideas to test this in a more robust way.

Thanks.

> diff --git a/bulk-checkin.c b/bulk-checkin.c
> index 98ec8938424..855b68ec23b 100644
> --- a/bulk-checkin.c
> +++ b/bulk-checkin.c
> @@ -340,6 +340,8 @@ void fsync_loose_object_bulk_checkin(int fd, const char *filename)
>  	 */
>  	if (!bulk_fsync_objdir ||
>  	    git_fsync(fd, FSYNC_WRITEOUT_ONLY) < 0) {
> +		if (errno == ENOSYS)
> +			warning(_("core.fsyncMethod = batch is unsupported on this platform"));
>  		fsync_or_die(fd, filename);
>  	}
>  }
> diff --git a/t/t5351-unpack-large-objects.sh b/t/t5351-unpack-large-objects.sh
> index f785cb06173..dd7ebc40072 100755
> --- a/t/t5351-unpack-large-objects.sh
> +++ b/t/t5351-unpack-large-objects.sh
> @@ -70,9 +70,15 @@ test_expect_success 'unpack big object in stream (core.fsyncmethod=batch)' '
>  	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
>  	GIT_TEST_FSYNC=true \
>  		git -C dest.git $BATCH_CONFIGURATION unpack-objects <pack-$PACK.pack &&
> -	check_fsync_events trace2.txt <<-\EOF &&
> +	if grep "core.fsyncMethod = batch is unsupported" trace2.txt
> +	then
> +		flush_count=7
> +	else
> +		flush_count=1
> +	fi &&
> +	check_fsync_events trace2.txt <<-EOF &&
>  	"key":"fsync/writeout-only","value":"6"
> -	"key":"fsync/hardware-flush","value":"1"
> +	"key":"fsync/hardware-flush","value":"$flush_count"
>  	EOF
>  
>  	test_dir_is_empty dest.git/objects/pack &&