git: unconditional expiry

A constant stream of traffic to either httpd/nntpd would mean
git-cat-file processes never expire.  Things can go bad after a
full repack, as a full repack will unlink old pack indices and
git-cat-file does not currently detect unlinked files.

We could do something complicated by recursively stat-ing
objects/pack of every git directory and alternate;
but that's probably not worth the trouble compared to
occasionally restarting the cat-file process.

So simplify the code and let httpd/nntpd expire them
periodically, since spawning a "git-cat-file --batch" process
isn't too expensive.  We already spawn for every request which
hits git-http-backend, cgit, and git-apply.

In the future, we may optionally support the Git::Raw module
to avoid IPC; but we must remain careful to not leave lingering
FDs open to unlinked files after repack.

1 files changed, 5 insertions, 15 deletions

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index a4daaa48..9a38d7c8 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -211,19 +211,9 @@ sub check {
 }
 
 sub _destroy {
-        my ($self, $in, $out, $pid, $expire) = @_;
-        my $rfh = $self->{$in} or return;
-        if (defined $expire) {
-                # at least FreeBSD 11.2 and Linux 4.20 update mtime of the
-                # read end of a pipe when the pipe is written to; dunno
-                # about other OSes.
-                my $mtime = (stat($rfh))[9];
-                return if $mtime > $expire;
-        }
+        my ($self, $in, $out, $pid) = @_;
         my $p = delete $self->{$pid} or return;
-        foreach my $f ($in, $out) {
-                delete $self->{$f};
-        }
+        delete @$self{($in, $out)};
         waitpid $p, 0;
 }
 
@@ -251,9 +241,9 @@ sub qx {
 
 # returns true if there are pending "git cat-file" processes
 sub cleanup {
-        my ($self, $expire) = @_;
-        _destroy($self, qw(in out pid), $expire);
-        _destroy($self, qw(in_c out_c pid_c), $expire);
+        my ($self) = @_;
+        _destroy($self, qw(in out pid));
+        _destroy($self, qw(in_c out_c pid_c));
         !!($self->{pid} || $self->{pid_c});
 }