[PATCH 29/30] solvergit: allow passing arg to user-supplied callback

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

This allows us to get rid of the requirement to capture
on-stack variables with an anonymous sub, as illustrated
with the update to viewvcs to take advantage of this.
---
 lib/PublicInbox/SolverGit.pm | 28 ++++++++++++++++------------
 lib/PublicInbox/ViewVCS.pm   | 19 ++++++++++---------
 2 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/lib/PublicInbox/SolverGit.pm b/lib/PublicInbox/SolverGit.pm
index 6dfa20f7..6b6586e9 100644
--- a/lib/PublicInbox/SolverGit.pm
+++ b/lib/PublicInbox/SolverGit.pm
@@ -55,11 +55,16 @@ sub dbg ($$) {
 	print { $_[0]->{out} } $_[1], "\n" or ERR($_[0], "print(dbg): $!");
 }
 
+sub done_err ($$) {
+	my ($self, $err) = @_;
+	my $ucb = delete($self->{user_cb}) or return;
+	$ucb->($err, $self->{uarg});
+}
+
 sub ERR ($$) {
 	my ($self, $err) = @_;
 	print { $self->{out} } $err, "\n";
-	my $ucb = delete($self->{user_cb});
-	eval { $ucb->($err) } if $ucb;
+	eval { done_err($self, $err) };
 	die $err;
 }
 
@@ -313,22 +318,21 @@ sub extract_old_mode ($) {
 
 sub do_finish ($$) {
 	my ($self, $user_cb) = @_;
-	my $found = $self->{found};
-	my $oid_want = $self->{oid_want};
+	my ($found, $oid_want, $uarg) = @$self{qw(found oid_want uarg)};
 	if (my $exists = $found->{$oid_want}) {
-		return $user_cb->($exists);
+		return $user_cb->($exists, $uarg);
 	}
 
 	# let git disambiguate if oid_want was too short,
 	# but long enough to be unambiguous:
 	my $tmp_git = $self->{tmp_git};
 	if (my @res = $tmp_git->check($oid_want)) {
-		return $user_cb->($found->{$res[0]});
+		return $user_cb->($found->{$res[0]}, $uarg);
 	}
 	if (my $err = $tmp_git->last_check_err) {
 		dbg($self, $err);
 	}
-	$user_cb->(undef);
+	$user_cb->(undef, $uarg);
 }
 
 sub do_step ($) {
@@ -362,8 +366,7 @@ sub do_step ($) {
 	if ($err) {
 		$err =~ s/^\s*Exception:\s*//; # bad word to show users :P
 		dbg($self, "E: $err");
-		my $ucb = delete($self->{user_cb});
-		eval { $ucb->($err) } if $ucb;
+		eval { done_err($self, $err) };
 	}
 }
 
@@ -524,7 +527,7 @@ sub resolve_patch ($$) {
 			join("\n", $found_git->pub_urls($self->{psgi_env})));
 
 		if ($cur_want eq $self->{oid_want} || $type ne 'blob') {
-			eval { delete($self->{user_cb})->($existing) };
+			eval { done_err($self, $existing) };
 			die "E: $@" if $@;
 			return;
 		}
@@ -569,11 +572,12 @@ sub resolve_patch ($$) {
 # this API is designed to avoid creating self-referential structures;
 # so user_cb never references the SolverGit object
 sub new {
-	my ($class, $ibx, $user_cb) = @_;
+	my ($class, $ibx, $user_cb, $uarg) = @_;
 
 	bless {
 		gits => $ibx->{-repo_objs},
 		user_cb => $user_cb,
+		uarg => $uarg,
 		# -cur_di, -qsp, -msg => temporary fields for Qspawn callbacks
 
 		# TODO: config option for searching related inboxes
@@ -591,7 +595,7 @@ sub solve ($$$$$) {
 
 	# should we even get here? Probably not, but somebody
 	# could be manually typing URLs:
-	return (delete $self->{user_cb})->(undef) if $oid_want =~ /\A0+\z/;
+	return done_err($self, undef) if $oid_want =~ /\A0+\z/;
 
 	$self->{oid_want} = $oid_want;
 	$self->{out} = $out;
diff --git a/lib/PublicInbox/ViewVCS.pm b/lib/PublicInbox/ViewVCS.pm
index a6dbb9a9..ead8c2b4 100644
--- a/lib/PublicInbox/ViewVCS.pm
+++ b/lib/PublicInbox/ViewVCS.pm
@@ -112,8 +112,10 @@ sub show_other ($$$$) {
 	$qsp->psgi_qx($env, undef, \&show_other_result, $ctx);
 }
 
+# user_cb for SolverGit, called as: user_cb->($result_or_error, $uarg)
 sub solve_result {
-	my ($ctx, $res, $log, $hints, $fn) = @_;
+	my ($res, $ctx) = @_;
+	my ($log, $hints, $fn) = delete @$ctx{qw(log hints fn)};
 
 	unless (seek($log, 0, 0)) {
 		$ctx->{env}->{'psgi.errors'}->print("seek(log): $!\n");
@@ -192,21 +194,20 @@ sub solve_result {
 sub show ($$;$) {
 	my ($ctx, $oid_b, $fn) = @_;
 	my $qp = $ctx->{qp};
-	my $hints = {};
+	my $hints = $ctx->{hints} = {};
 	while (my ($from, $to) = each %QP_MAP) {
 		defined(my $v = $qp->{$from}) or next;
 		$hints->{$to} = $v;
 	}
 
-	my $log = tmpfile("solve.$oid_b");
-	my $solver = PublicInbox::SolverGit->new($ctx->{-inbox}, sub {
-		solve_result($ctx, $_[0], $log, $hints, $fn);
-	});
-
-	# PSGI server will call this and give us a callback
+	$ctx->{'log'} = tmpfile("solve.$oid_b");
+	$ctx->{fn} = $fn;
+	my $solver = PublicInbox::SolverGit->new($ctx->{-inbox},
+						\&solve_result, $ctx);
+	# PSGI server will call this immediately and give us a callback (-wcb)
 	sub {
 		$ctx->{-wcb} = $_[0]; # HTTP write callback
-		$solver->solve($ctx->{env}, $log, $oid_b, $hints);
+		$solver->solve($ctx->{env}, $ctx->{log}, $oid_b, $hints);
 	};
 }