viewvcs: don't wait on slow disks for git commit titles

We can easily wire into the DS event loop to take advantage
of epoll/kevent notifications and serve other clients in
the mean time.

1 files changed, 61 insertions, 46 deletions

diff --git a/lib/PublicInbox/ViewVCS.pm b/lib/PublicInbox/ViewVCS.pm
index 4533af3a..9bf010c2 100644
--- a/lib/PublicInbox/ViewVCS.pm
+++ b/lib/PublicInbox/ViewVCS.pm
@@ -17,6 +17,7 @@ use strict;
 use v5.10.1;
 use File::Temp 0.19 (); # newdir
 use PublicInbox::SolverGit;
+use PublicInbox::GitAsyncCat;
 use PublicInbox::WwwStream qw(html_oneshot);
 use PublicInbox::Linkify;
 use PublicInbox::Tmpfile;
@@ -32,7 +33,7 @@ my $hl = eval {
 my %QP_MAP = ( A => 'oid_a', a => 'path_a', b => 'path_b' );
 our $MAX_SIZE = 1024 * 1024; # TODO: configurable
 my $BIN_DETECT = 8000; # same as git
-my $SHOW_FMT = '--pretty=format:'.join('%n', '%H', '%T', '%P', '%p', '%s',
+my $SHOW_FMT = '--pretty=format:'.join('%n', '%P', '%p', '%H', '%T', '%s',
         '%an <%ae>  %ai', '%cn <%ce>  %ci', '%b%x00');
 
 sub html_page ($$$) {
@@ -94,32 +95,49 @@ sub show_other_result ($$) {
 }
 
 sub cmt_title { # git->cat_async callback
-        my ($bref, $oid, $type, $size, $pt) = @_;
+        my ($bref, $oid, $type, $size, $ctx) = @_;
         utf8::decode($$bref);
-        if ($$bref =~ /\r?\n\r?\n([^\r\n]+)\r?\n?/) {
-                push @$pt, $1;
-                ascii_html($pt->[-1]);
-        } else {
-                push @$pt, ''; # need a placeholder if blank commit
-        }
+        my $title = $$bref =~ /\r?\n\r?\n([^\r\n]+)\r?\n?/ ? $1 : '';
+        push(@{$ctx->{-cmt_pt}} , ascii_html($title)) == @{$ctx->{-cmt_P}} and
+                cmt_finalize($ctx);
 }
 
-sub show_commit_result ($$) {
+sub show_commit_start { # ->psgi_qx callback
         my ($bref, $ctx) = @_;
-        my ($qsp_err, $logref, $tmp) = @$ctx{qw(-qsp_err -logref -tmp)};
+        my ($qsp_err, $logref) = delete @$ctx{qw(-qsp_err -logref)};
         if ($qsp_err) {
                 $$logref .= "git show/patch-id error:$qsp_err";
                 return html_page($ctx, 500, $logref);
         }
-        my $upfx = $ctx->{-upfx} = '../../'; # from "/$INBOX/$OID/s/"
         my $patchid = (split(/ /, $$bref))[0]; # ignore commit
         $ctx->{-q_value_html} = "patchid:$patchid" if defined $patchid;
-        my $l = $ctx->{-linkify} = PublicInbox::Linkify->new;
-        open my $fh, '<:utf8', "$tmp/h" or die "open $tmp/h: $!";
+        open my $fh, '<:utf8', "$ctx->{-tmp}/h" or
+                die "open $ctx->{-tmp}/h: $!";
         chop(my $buf = do { local $/ = "\0"; <$fh> });
-        my ($H, $T, $P, $p, $s, $au, $co, $bdy) = split(/\n/, $buf, 8);
-        chomp $bdy;
+        chomp $buf;
+        my ($P, $p);
+        ($P, $p, @$ctx{qw(cmt_H cmt_T cmt_s cmt_au cmt_co cmt_b)})
+                = split(/\n/, $buf, 8);
+        return cmt_finalize($ctx) if !$P;
+        @{$ctx->{-cmt_P}} = split(/ /, $P);
+        @{$ctx->{-cmt_p}} = split(/ /, $p); # abbreviated
+        if ($ctx->{env}->{'pi-httpd.async'}) {
+                for (@{$ctx->{-cmt_P}}) {
+                        ibx_async_cat($ctx, $_, \&cmt_title, $ctx);
+                }
+        } else { # synchronous
+                for (@{$ctx->{-cmt_P}}) {
+                        $ctx->{git}->cat_async($_, \&cmt_title, $ctx);
+                }
+                $ctx->{git}->cat_async_wait;
+        }
+}
+
+sub cmt_finalize {
+        my ($ctx) = @_;
+        $ctx->{-linkify} = PublicInbox::Linkify->new;
         # try to keep author and committer dates lined up
+        my ($au, $co) = delete @$ctx{qw(cmt_au cmt_co)};
         my $x = length($au) - length($co);
         if ($x > 0) {
                 $x = ' ' x $x;
@@ -129,49 +147,46 @@ sub show_commit_result ($$) {
                 $au =~ s/>/>$x/;
         }
         $_ = ascii_html($_) for ($au, $co);
-        $_ = $l->to_html($_) for ($s, $bdy);
+        my $s = $ctx->{-linkify}->to_html(delete $ctx->{cmt_s});
         $ctx->{-title_html} = $s;
-        my @P = split(/ /, $P);
-        my @p = split(/ /, $p); # abbreviated
-        my @pt;
-        my $git = delete $ctx->{code_git};
-        $git->cat_async($_, \&cmt_title, \@pt) for @P;
-        $git->cat_async_wait;
-        $_ = qq(<a href="$upfx$_/s/">).shift(@p).'</a> '.shift(@pt) for @P;
-        if (@P == 1) {
-                $P = qq(\n   parent $P[0]);
-        } elsif (@P > 1) {
-                $P = qq(\n  parents $P[0]\n);
-                shift @P;
-                $P .= qq(          $_\n) for @P;
-                chop $P;
-        } else { # root commit
-                $P = ' (root commit)';
+        my $upfx = $ctx->{-upfx} = '../../'; # from "/$INBOX/$OID/s/"
+        my ($P, $p, $pt) = delete @$ctx{qw(-cmt_P -cmt_p -cmt_pt)};
+        $_ = qq(<a href="$upfx$_/s/">).shift(@$p).'</a> '.shift(@$pt) for @$P;
+        if (@$P == 1) {
+                $x = qq(\n   parent $P->[0]);
+        } elsif (@$P > 1) {
+                $x = qq(\n  parents $P->[0]\n);
+                shift @$P;
+                $x .= qq(          $_\n) for @$P;
+                chop $x;
+        } else {
+                $x = ' (root commit)';
         }
         PublicInbox::WwwStream::html_init($ctx);
         $ctx->zmore(<<EOM);
-<pre>   commit $H$P
-     tree <a href="$upfx$T/s/">$T</a>
+<pre>   commit $ctx->{cmt_H}$x
+     tree <a href="$upfx$ctx->{cmt_T}/s/">$ctx->{cmt_T}</a>
    author $au
 committer $co
 
-<b>$s</b>\n
+<b>$s</b>
 EOM
-        $ctx->zmore($bdy);
-        open $fh, '<:utf8', "$tmp/p" or die "open $tmp/p: $!";
+        $x = delete $ctx->{cmt_b};
+        $ctx->zmore("\n", $ctx->{-linkify}->to_html($x)) if length($x);
+        undef $x;
+        open my $fh, '<:utf8', "$ctx->{-tmp}/p" or
+                die "open $ctx->{-tmp}/p: $!";
         if (-s $fh > $MAX_SIZE) {
                 $ctx->zmore("---\n patch is too large to show\n");
         } else { # prepare flush_diff:
-                $buf = '';
-                $ctx->{obuf} = \$buf;
+                $ctx->{obuf} = \$x;
                 $ctx->{-apfx} = $ctx->{-spfx} = $upfx;
-                $bdy = '';
-                read($fh, $bdy, -s _);
+                read($fh, my $bdy, -s _);
                 $bdy =~ s/\r?\n/\n/gs;
                 $ctx->{-anchors} = {} if $bdy =~ /^diff --git /sm;
-                flush_diff($ctx, \$bdy);
-                $ctx->zmore($buf);
-                undef $buf;
+                flush_diff($ctx, \$bdy); # undefs $bdy
+                $ctx->zmore($x);
+                undef $x;
                 # TODO: should there be another textarea which attempts to
                 # search for the exact email which was applied to make this
                 # commit?
@@ -223,8 +238,8 @@ sub show_commit ($$$$) {
         $ctx->{-logref} = $logref;
         $ctx->{-tmp} = $tmp;
         $ctx->{env}->{'qspawn.wcb'} = delete $ctx->{-wcb};
-        $ctx->{code_git} = $git;
-        $qsp->psgi_qx($ctx->{env}, undef, \&show_commit_result, $ctx);
+        $ctx->{git} = $git;
+        $qsp->psgi_qx($ctx->{env}, undef, \&show_commit_start, $ctx);
 }
 
 sub show_other ($$$$) {