Re: [PATCH 1/2] git: use --batch-command in git 2.36+ to save processes

[Eric Wong <e@80x24.org>]

t/imapd.t on my slower 32-bit machine fails without the
following fix.  I guess prefetch wasn't being tested on my
faster workstation?

Also, the prior use of `print { $git->{out} }' is a potential (but
unlikely) bug since commit d4ba8828ab23f278
(git: fix asynchronous batching for deep pipelines, 2023-01-04)

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 1c77b4ce..a9db8ad7 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -239,6 +239,16 @@ sub cat_async_retry ($$) {
 	cat_async_step($self, $inflight); # take one step
 }
 
+# returns true if prefetch is successful
+sub async_prefetch {
+	my ($self, $oid, $cb, $arg) = @_;
+	my $inflight = $self->{inflight} or return;
+	return if @$inflight;
+	substr($oid, 0, 0) = 'contents ' if $self->{-bc};
+	write_all($self, $self->{out}, "$oid\n", \&cat_async_step, $inflight);
+	push(@$inflight, $oid, $cb, $arg);
+}
+
 sub cat_async_step ($$) {
 	my ($self, $inflight) = @_;
 	die 'BUG: inflight empty or odd' if scalar(@$inflight) < 3;
diff --git a/lib/PublicInbox/GitAsyncCat.pm b/lib/PublicInbox/GitAsyncCat.pm
index 1f86aad0..49a3c602 100644
--- a/lib/PublicInbox/GitAsyncCat.pm
+++ b/lib/PublicInbox/GitAsyncCat.pm
@@ -98,12 +98,8 @@ sub ibx_async_prefetch {
 			$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, $arg);
-		}
+	} elsif ($git->{async_cat}) {
+		return $git->async_prefetch($oid, $cb, $arg);
 	}
 	undef;
 }