-sub git_async_msg ($$$$) {
- my ($ibx, $smsg, $cb, $arg) = @_;
- $ibx->git->cat_async($smsg->{blob}, $cb, $arg);
- $ibx->{async_cat} //= new(__PACKAGE__, $ibx->{git});
+sub ibx_async_cat ($$$$) {
+ my ($ibx, $oid, $cb, $arg) = @_;
+ my $git = $ibx->{git} // $ibx->git;
+ # {topdir} means ExtSearch (likely [extindex "all"]) with potentially
+ # 100K alternates. git(1) has a proposed patch for 100K alternates:
+ # <https://lore.kernel.org/git/20210624005806.12079-1-e@80x24.org/>
+ if (!defined($ibx->{topdir}) && !defined($git->{-tmp}) &&
+ ($GCF2C //= eval {
+ require PublicInbox::Gcf2Client;
+ PublicInbox::Gcf2Client::new();
+ } // 0)) { # 0: do not retry if libgit2 or Inline::C are missing
+ $GCF2C->gcf2_async(\"$oid $git->{git_dir}\n", $cb, $arg);
+ \undef;
+ } else { # read-only end of git-cat-file pipe
+ $git->cat_async($oid, $cb, $arg);
+ watch_cat($git);
+ }
+}
+
+# this is safe to call inside $cb, but not guaranteed to enqueue
+# returns true if successful, undef if not. For fairness, we only
+# prefetch if there's no in-flight requests.
+sub ibx_async_prefetch {
+ my ($ibx, $oid, $cb, $arg) = @_;
+ my $git = $ibx->git;
+ if (!defined($ibx->{topdir}) && $GCF2C) {
+ if (!@{$GCF2C->{inflight} // []}) {
+ $oid .= " $git->{git_dir}\n";
+ return $GCF2C->gcf2_async(\$oid, $cb, $arg); # true
+ }
+ } elsif ($git->{async_cat} && (my $inflight = $git->{inflight})) {
+ if (!@$inflight) {
+ print { $git->{out} } $oid, "\n" or
+ $git->fail("write error: $!");
+ return push(@$inflight, $oid, $cb, $arg);
+ }
+ }
+ undef;