[PATCH] gitweb: only display "next" links in logs if there is a next page

[PATCH] gitweb: only display "next" links in logs if there is a next page

[Lea Wiemann]

There was a bug in the implementation of the "next" links in
format_paging_nav (for log and shortlog), which caused the next links
to always be displayed, even if there is no next page.  This fixes it.

Signed-off-by: Lea Wiemann <LeWiemann@gmail.com>
---
 gitweb/gitweb.perl |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 308fde2..874f53a 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -2752,7 +2752,7 @@ sub git_print_page_nav {
 }
 
 sub format_paging_nav {
-	my ($action, $hash, $head, $page, $has_more_pages) = @_;
+	my ($action, $hash, $head, $page, $has_next_link) = @_;
 	my $paging_nav;
 
 
@@ -2770,7 +2770,7 @@ sub format_paging_nav {
 		$paging_nav .= " &sdot; prev";
 	}
 
-	if ($has_more_pages) {
+	if ($has_next_link) {
 		$paging_nav .= " &sdot; " .
 			$cgi->a({-href => href(-replay=>1, page=>$page+1),
 			         -accesskey => "n", -title => "Alt-n"}, "next");
@@ -4661,7 +4661,7 @@ sub git_log {
 
 	my @commitlist = parse_commits($hash, 101, (100 * $page));
 
-	my $paging_nav = format_paging_nav('log', $hash, $head, $page, $#commitlist > 99);
+	my $paging_nav = format_paging_nav('log', $hash, $head, $page, $#commitlist >= 100);
 
 	git_header_html();
 	git_print_page_nav('log','', $hash,undef,undef, $paging_nav);
@@ -5581,7 +5581,7 @@ sub git_shortlog {
 
 	my @commitlist = parse_commits($hash, 101, (100 * $page));
 
-	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, $#commitlist > 99);
+	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, $#commitlist >= 100);
 	my $next_link = '';
 	if ($#commitlist >= 100) {
 		$next_link =
-- 
1.5.5.1

Re: [PATCH] gitweb: only display "next" links in logs if there is a next page

[Junio C Hamano]

Lea Wiemann <lewiemann@gmail.com> writes:

> There was a bug in the implementation of the "next" links in
> format_paging_nav (for log and shortlog), which caused the next links
> to always be displayed, even if there is no next page.  This fixes it.
>
> Signed-off-by: Lea Wiemann <LeWiemann@gmail.com>
> ---
>  gitweb/gitweb.perl |    8 ++++----
>  1 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
> index 308fde2..874f53a 100755
> --- a/gitweb/gitweb.perl
> +++ b/gitweb/gitweb.perl
> @@ -2752,7 +2752,7 @@ sub git_print_page_nav {
>  }
>  
>  sub format_paging_nav {
> -	my ($action, $hash, $head, $page, $has_more_pages) = @_;
> +	my ($action, $hash, $head, $page, $has_next_link) = @_;
>  	my $paging_nav;
>  
>  
> @@ -2770,7 +2770,7 @@ sub format_paging_nav {
>  		$paging_nav .= " &sdot; prev";
>  	}
>  
> -	if ($has_more_pages) {
> +	if ($has_next_link) {
>  		$paging_nav .= " &sdot; " .
>  			$cgi->a({-href => href(-replay=>1, page=>$page+1),
>  			         -accesskey => "n", -title => "Alt-n"}, "next");

This looks like a no-op hunk, unless format_paging_nav sub has other uses
of $has_more_pages variable.  But the copies of gitweb I have do not begin
with these lines, but they begin like this:

        sub format_paging_nav {
                my ($action, $hash, $head, $page, $nrevs) = @_;
                my $paging_nav;

On what version is your patch based on?  I checked warthog9's copy and
that also seems to be different.

> @@ -4661,7 +4661,7 @@ sub git_log {
>  
>  	my @commitlist = parse_commits($hash, 101, (100 * $page));
>  
> -	my $paging_nav = format_paging_nav('log', $hash, $head, $page, $#commitlist > 99);
> +	my $paging_nav = format_paging_nav('log', $hash, $head, $page, $#commitlist >= 100);
>  
>  	git_header_html();
>  	git_print_page_nav('log','', $hash,undef,undef, $paging_nav);
> @@ -5581,7 +5581,7 @@ sub git_shortlog {
>  
>  	my @commitlist = parse_commits($hash, 101, (100 * $page));
>  
> -	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, $#commitlist > 99);
> +	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, $#commitlist >= 100);
>  	my $next_link = '';
>  	if ($#commitlist >= 100) {
>  		$next_link =

I am not very good at counting, but the change looks no-op to me.  Either
the last index of the list variable is strictly larger than 99, or it is
100 or greater --- aren't they the same thing?

A bit confused I am...

Re: [PATCH] gitweb: only display "next" links in logs if there is a next page

[Lea Wiemann]

Junio C Hamano wrote:
> This looks like a no-op hunk,

Argh!  Apologies, I'm new to git and accidentally only sent my second 
commit -- I should've checked more carefully.  I'll re-send the correct 
patch as a follow-up to this email.  Sorry again! :(

Best,

     Lea

[PATCH] gitweb: only display "next" links in logs if there is a next page

[Lea Wiemann]

There was a bug in the implementation of the "next" links in
format_paging_nav (for log and shortlog), which caused the next links
to always be displayed, even if there is no next page.  This fixes it.

Signed-off-by: Lea Wiemann <LeWiemann@gmail.com>
---
 gitweb/gitweb.perl |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 8308e22..57a1905 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -2756,7 +2756,7 @@ sub git_print_page_nav {
 }
 
 sub format_paging_nav {
-	my ($action, $hash, $head, $page, $nrevs) = @_;
+	my ($action, $hash, $head, $page, $has_next_link) = @_;
 	my $paging_nav;
 
 
@@ -2774,7 +2774,7 @@ sub format_paging_nav {
 		$paging_nav .= " &sdot; prev";
 	}
 
-	if ($nrevs >= (100 * ($page+1)-1)) {
+	if ($has_next_link) {
 		$paging_nav .= " &sdot; " .
 			$cgi->a({-href => href(-replay=>1, page=>$page+1),
 			         -accesskey => "n", -title => "Alt-n"}, "next");
@@ -4665,7 +4665,7 @@ sub git_log {
 
 	my @commitlist = parse_commits($hash, 101, (100 * $page));
 
-	my $paging_nav = format_paging_nav('log', $hash, $head, $page, (100 * ($page+1)));
+	my $paging_nav = format_paging_nav('log', $hash, $head, $page, $#commitlist >= 100);
 
 	git_header_html();
 	git_print_page_nav('log','', $hash,undef,undef, $paging_nav);
@@ -5585,7 +5585,7 @@ sub git_shortlog {
 
 	my @commitlist = parse_commits($hash, 101, (100 * $page));
 
-	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, (100 * ($page+1)));
+	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, $#commitlist >= 100);
 	my $next_link = '';
 	if ($#commitlist >= 100) {
 		$next_link =
-- 
1.5.5.1

Re: [PATCH] gitweb: only display "next" links in logs if there is a next page

[Lea Wiemann]

Lea Wiemann wrote:
> There was a bug in the implementation of the "next" links in
> format_paging_nav (for log and shortlog), which caused the next links
> to always be displayed, even if there is no next page.  This fixes it.

Oh, one more thing I forgot to mention: I've tested this with a small 
(single-page) log page and a long log page.  In both cases the "next" 
links get formatted correctly, and they stop linking to the next page on 
the correct (= last) page.  The only thing I haven't tested for is 
off-by-one errors, but I'm reasonably sure that $#commitlist >= 100 is 
right.

-- Lea

Re: [PATCH] gitweb: only display "next" links in logs if there is a next page

[Junio C Hamano]

Lea Wiemann <lewiemann@gmail.com> writes:

> Lea Wiemann wrote:
>> There was a bug in the implementation of the "next" links in
>> format_paging_nav (for log and shortlog), which caused the next links
>> to always be displayed, even if there is no next page.  This fixes it.
>
> Oh, one more thing I forgot to mention: I've tested this with a small
> (single-page) log page and a long log page.  In both cases the "next"
> links get formatted correctly, and they stop linking to the next page
> on the correct (= last) page.  The only thing I haven't tested for is
> off-by-one errors, but I'm reasonably sure that $#commitlist >= 100 is
> right.

I do not trust people who rely on "tests" to catch counting errors
(although I am pretty bad at counting myself and often testsuite helps me
catch my own bugs).  Instead, let's follow the code to see if it is Ok.

You call format_paging_nav() from two places, both after calling
parse_commits() with $maxcount = 101.  So @commitlist could have 101
elements (in which case you would need to have next page because you will
show only 100 among them), or smaller than that (in which case you will
fully show them).  In other words, you would want to say 'next' iff

	(@commitlist > 100)

is true.  On the other hand, $#commitlist is the last index of @commitlist
array, which is one smaller than the number of elements in that array.
IOW, when it has 101 elements, it has $commitlist[0] thru $commitlist[100]
and $#commitlist == 100.  So the above condition is the same as

	($#commitlist >= 100)

So your counting looks correct to me.

I wonder if it is easier to read to use the more modern @array notation
than historic $#array notation (it looks very Perl 4 to me), but that is a
separate issue.  gitweb is littered with such anachronism ;-)

Re: [PATCH] gitweb: only display "next" links in logs if there is a next page

[Lea Wiemann]

Junio C Hamano wrote:
> I do not trust people who rely on "tests" to catch counting errors

Oh, I wasn't trying to say that I didn't "brain-check" my code for 
correctness -- I just think it's a good idea to actually test it in 
addition to that. :)

Anyways, thanks for reviewing and confirming it!

> I wonder if it is easier to read to use the more modern @array notation
> than historic $#array notation (it looks very Perl 4 to me), but that is a
> separate issue.  gitweb is littered with such anachronism ;-)

Yup, I was trying to be consistent there.

-- Lea

Re: [PATCH] gitweb: only display "next" links in logs if there is a next page

[Jakub Narebski]

Lea Wiemann <lewiemann@gmail.com> writes:

> There was a bug in the implementation of the "next" links in
> format_paging_nav (for log and shortlog), which caused the next links
> to always be displayed, even if there is no next page.  This fixes it.

Thanks for correcting this.

>  sub format_paging_nav {
> -	my ($action, $hash, $head, $page, $nrevs) = @_;
> +	my ($action, $hash, $head, $page, $has_next_link) = @_;
>  	my $paging_nav;
>  
>  
> @@ -2774,7 +2774,7 @@ sub format_paging_nav {
>  		$paging_nav .= " &sdot; prev";
>  	}
>  
> -	if ($nrevs >= (100 * ($page+1)-1)) {
> +	if ($has_next_link) {
>  		$paging_nav .= " &sdot; " .
>  			$cgi->a({-href => href(-replay=>1, page=>$page+1),
>  			         -accesskey => "n", -title => "Alt-n"}, "next");

This makes logic much simpler.  Nice change.

> @@ -4665,7 +4665,7 @@ sub git_log {
>  
>  	my @commitlist = parse_commits($hash, 101, (100 * $page));

Here I have realized the source of this bug.  Some time ago
git-rev-list acquired '--skip=<number>' option to have _git_ skip
commits and not _gitweb_, which improves performance a bit.  It was
required to implement huge performance improvement, namely getting
details for all commits from a single command, otherwise the
performance improvement of calling one git command instead of
$page_size git commands would be much reduced by generating large
amount of data which would be skipped (wound't be used by gitweb).

Unfortunately this change wasn't reviewed carefully enough; old logic
to decide whether to add 'next' link compared (tried to compare)
number of commits receivied with number of commits requested (via
'--max-count=<number>' option).  I guess that having format_paging_nav
decide whether to add "next" link was a bad idea...

> -	my $paging_nav = format_paging_nav('log', $hash, $head, $page, (100 * ($page+1)));
> +	my $paging_nav = format_paging_nav('log', $hash, $head, $page, $#commitlist >= 100);
> 

I would agree with Junio here that @commitlist > 100 would be more
readable.

Logic goes as the following: we request ($page_size+1) revisions to
know if there are additional revisions, skipping ($page_size * $page)
revisions; gitweb adds 'next' link if it got more than $page_size
revisions.
 
>  	git_header_html();
>  	git_print_page_nav('log','', $hash,undef,undef, $paging_nav);
> @@ -5585,7 +5585,7 @@ sub git_shortlog {
>  
>  	my @commitlist = parse_commits($hash, 101, (100 * $page));
>  
> -	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, (100 * ($page+1)));
> +	my $paging_nav = format_paging_nav('shortlog', $hash, $head, $page, $#commitlist >= 100);
>  	my $next_link = '';
>  	if ($#commitlist >= 100) {
>  		$next_link =

What about git_history()... oh, I see, it generates paging itself, and
soes not use format_paging_nav() subroutine.  But I think it does not
exhibit mentioned (and corrected) error.  BTW. I *guess* that with
href(-replay=>1, ...) gitweb could use format_paging_nav() also for
other pages...

-- 
Jakub Narebski
Poland
ShadeHawk on #git