1 files changed, 39 insertions, 9 deletions

diff --git a/lib/PublicInbox/ViewVCS.pm b/lib/PublicInbox/ViewVCS.pm
index 61329db6..790b9a2c 100644
--- a/lib/PublicInbox/ViewVCS.pm
+++ b/lib/PublicInbox/ViewVCS.pm
@@ -49,6 +49,10 @@ my %GIT_MODE = (
         '160000' => 'g', # commit (gitlink)
 );
 
+# TODO: not fork safe, but we don't fork w/o exec in PublicInbox::WWW
+my (@solver_q, $solver_lim);
+my $solver_nr = 0;
+
 sub html_page ($$;@) {
         my ($ctx, $code) = @_[0, 1];
         my $wcb = delete $ctx->{-wcb};
@@ -614,26 +618,52 @@ sub show_blob { # git->cat_async callback
                 '</code></pre></td></tr></table>'.dbg_log($ctx), @def);
 }
 
-# GET /$INBOX/$GIT_OBJECT_ID/s/
-# GET /$INBOX/$GIT_OBJECT_ID/s/$FILENAME
-sub show ($$;$) {
-        my ($ctx, $oid_b, $fn) = @_;
-        my $hints = $ctx->{hints} = {};
+sub start_solver ($) {
+        my ($ctx) = @_;
         while (my ($from, $to) = each %QP_MAP) {
                 my $v = $ctx->{qp}->{$from} // next;
-                $hints->{$to} = $v if $v ne '';
+                $ctx->{hints}->{$to} = $v if $v ne '';
         }
-        $ctx->{fn} = $fn;
-        $ctx->{-tmp} = File::Temp->newdir("solver.$oid_b-XXXX", TMPDIR => 1);
+        $ctx->{-next_solver} = PublicInbox::OnDestroy->new($$, \&next_solver);
+        ++$solver_nr;
+        $ctx->{-tmp} = File::Temp->newdir("solver.$ctx->{oid_b}-XXXX",
+                                                TMPDIR => 1);
         $ctx->{lh} or open $ctx->{lh}, '+>>', "$ctx->{-tmp}/solve.log";
         my $solver = PublicInbox::SolverGit->new($ctx->{ibx},
                                                 \&solve_result, $ctx);
+        $solver->{limiter} = $solver_lim;
         $solver->{gits} //= [ $ctx->{git} ];
         $solver->{tmp} = $ctx->{-tmp}; # share tmpdir
         # PSGI server will call this immediately and give us a callback (-wcb)
+        $solver->solve(@$ctx{qw(env lh oid_b hints)});
+}
+
+# run the next solver job when done and DESTROY-ed
+sub next_solver {
+        --$solver_nr;
+        # XXX FIXME: client may've disconnected if it waited a long while
+        start_solver(shift(@solver_q) // return);
+}
+
+sub may_start_solver ($) {
+        my ($ctx) = @_;
+        $solver_lim //= $ctx->{www}->{pi_cfg}->limiter('codeblob');
+        if ($solver_nr >= $solver_lim->{max}) {
+                @solver_q > 128 ? html_page($ctx, 503, 'too busy')
+                                : push(@solver_q, $ctx);
+        } else {
+                start_solver($ctx);
+        }
+}
+
+# GET /$INBOX/$GIT_OBJECT_ID/s/
+# GET /$INBOX/$GIT_OBJECT_ID/s/$FILENAME
+sub show ($$;$) {
+        my ($ctx, $oid_b, $fn) = @_;
+        @$ctx{qw(oid_b fn)} = ($oid_b, $fn);
         sub {
                 $ctx->{-wcb} = $_[0]; # HTTP write callback
-                $solver->solve($ctx->{env}, $ctx->{lh}, $oid_b, $hints);
+                may_start_solver $ctx;
         };
 }