Re: Re: [PATCH v2] rev-list: support human-readable output for `--disk-usage`

["lilinchao@oschina.cn" <lilinchao@oschina.cn>]

>On Mon, Aug 08, 2022 at 08:35:21AM +0000, Li Linchao via GitGitGadget wrote:
>
>> The '--disk-usage' option for git-rev-list was introduced in 16950f8384
>> (rev-list: add --disk-usage option for calculating disk usage, 2021-02-09).
>> This is very useful for people inspect their git repo's objects usage
>> infomation, but the resulting number is quit hard for a human to read.
>>
>> Teach git rev-list to output a human readable result when using
>> '--disk-usage'.
>
>OK. When adding --disk-usage, I never really dreamed people would use it
>for human output, since "du .git" is usually a suitable approximation. :)
>But I don't have any real objection. I'm curious what your use case is
>like, if you don't mind sharing. We used it at GitHub for computing
>per-fork sizes for analysis, etc (so the result was always fed into
>another script).
Sometimes, I need objects disk size for analysis too, but I do this by hand
not by script. And I also noticed that git-count-objects has an option '-H'
for better output, so I think if it could be applied to "git-rev-list --disk-usage".
>
>>  Documentation/rev-list-options.txt |  5 +++-
>>  builtin/rev-list.c                 | 42 ++++++++++++++++++++++++------
>>  t/t6115-rev-list-du.sh             | 22 ++++++++++++++++
>>  3 files changed, 60 insertions(+), 9 deletions(-)
>
>The patch itself looks pretty sensible (and thanks Ævar for the first
>round of review; the suggestions there all looked good). A few small
>comments:
>
>> @@ -481,8 +485,13 @@ static int try_bitmap_disk_usage(struct rev_info *revs,
>>  if (!bitmap_git)
>>  return -1;
>> 
>> -	printf("%"PRIuMAX"\n",
>> -	       (uintmax_t)get_disk_usage_from_bitmap(bitmap_git, revs));
>> +	size_from_bitmap = get_disk_usage_from_bitmap(bitmap_git, revs);
>> +	if (human_readable)
>> +	strbuf_humanise_bytes(&disk_buf, size_from_bitmap);
>> +	else
>> +	strbuf_addf(&disk_buf, "%"PRIuMAX"", (uintmax_t)size_from_bitmap);
>> +	puts(disk_buf.buf);
>> +	strbuf_release(&disk_buf);
>
>It's not a lot of duplicated lines, but since it is implementing policy
>logic, I think it would be nice to move the formatting decision into a
>function. Something like:
>
>  static void show_disk_usage(off_t size)
>  {
>	struct strbuf sb = STRBUF_INIT;
>	if (human_readable)
>	strbuf_humanise_bytes(&sb, size);
>	else
>	strbuf_addf(&sb, "%"PRIuMAX, (uintmax_t)size_from_bitmap);
>	puts(sb.buf);
>	strbuf_release(&sb);
>  }
>
>and then you can call it from here, and from the non-bitmap path below.
Oh, this is really good.
>
>(Also, while typing it out, I noticed that you don't need the extra ""
>after PRIuMAX; that just concatenates an empty string).
>
>> -	if (!strcmp(arg, "--disk-usage")) {
>> -	show_disk_usage = 1;
>> -	info.flags |= REV_LIST_QUIET;
>> -	continue;
>> +	if (skip_prefix(arg, "--disk-usage", &arg)) {
>> +	if (*arg == '=') {
>> +	if (!strcmp(++arg, "human")) {
>> +	human_readable = 1;
>> +	show_disk_usage = 1;
>> +	info.flags |= REV_LIST_QUIET;
>> +	continue;
>> +	} else
>> +	die(_("invalid value for '%s': '%s', try --disk-usage=human"), "--disk-usage", arg);
>> +	} else {
>> +	show_disk_usage = 1;
>> +	info.flags |= REV_LIST_QUIET;
>> +	continue;
>> +	}
>>  }
>
>We can put the common parts of each side of the conditional into the
>outer block to avoid repeating ourselves. Also, your code matches
>--show-disk-usage-without-an-equals, since it nows uses skip_prefix().
>You could fix that by checking for '\0' in *arg. So together, something
>like:
>
>  if (skip_prefix(arg, "--disk-usage", &arg)) {
>	if (*arg == '=') {
>	if (!strcmp(++arg, "human"))
>	human_readable = 1;
>	else
>	die(...);
>	} else if (*arg) {
>	/*
>	* Arguably should goto a label to continue chain of ifs?
>	* Doesn't matter unless we try to add --disk-usage-foo
>	* afterwards
>	*/
>	usage(rev_list_usage);
>	}
>	show_disk_usage = 1;
>	info.flags |= REV_LIST_QUIET;
>	continue;
>  }
Thank you a lot for your very nice suggestions.

>
>-Peff