1 files changed, 73 insertions, 21 deletions

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 218846f3..90595840 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -16,6 +16,11 @@ use PublicInbox::Tmpfile;
 use base qw(Exporter);
 our @EXPORT_OK = qw(git_unquote git_quote);
 
+use constant MAX_INFLIGHT =>
+        ($^O eq 'linux' ? 4096 : POSIX::_POSIX_PIPE_BUF())
+        /
+        65; # SHA-256 hex size + "\n" in preparation for git using non-SHA1
+
 my %GIT_ESC = (
         a => "\a",
         b => "\b",
@@ -124,10 +129,50 @@ sub _bidi_pipe {
         $self->{$in} = $in_r;
 }
 
+sub read_cat_in_full ($$$) {
+        my ($self, $in, $left) = @_;
+        my $offset = 0;
+        my $buf = '';
+        while ($left > 0) {
+                my $r = read($in, $buf, $left, $offset);
+                defined($r) or fail($self, "read failed: $!");
+                $r == 0 and fail($self, 'exited unexpectedly');
+                $left -= $r;
+                $offset += $r;
+        }
+        my $r = read($in, my $lf, 1);
+        defined($r) or fail($self, "read failed: $!");
+        fail($self, 'newline missing after blob') if ($r != 1 || $lf ne "\n");
+        \$buf;
+}
+
+sub _cat_async_step ($$$) {
+        my ($self, $inflight, $in) = @_;
+        my $cb = shift @$inflight or die 'BUG: inflight empty';
+        local $/ = "\n";
+        my $head = $in->getline;
+        return eval { $cb->(undef) } if $head =~ / missing$/;
+
+        $head =~ /^([0-9a-f]{40}) (\S+) ([0-9]+)$/ or
+                fail($self, "Unexpected result from async git cat-file: $head");
+        my ($oid_hex, $type, $size) = ($1, $2, $3 + 0);
+        my $bref = read_cat_in_full($self, $in, $size);
+        eval { $cb->($bref, $oid_hex, $type, $size) };
+}
+
+sub cat_async_wait ($) {
+        my ($self) = @_;
+        my $inflight = delete $self->{inflight} or return;
+        my $in = $self->{in};
+        while (scalar(@$inflight)) {
+                _cat_async_step($self, $inflight, $in);
+        }
+}
+
 sub cat_file {
         my ($self, $obj, $ref) = @_;
         my ($retried, $in, $head);
-
+        cat_async_wait($self);
 again:
         batch_prepare($self);
         $self->{out}->print($obj, "\n") or fail($self, "write error: $!");
@@ -147,26 +192,8 @@ again:
                 fail($self, "Unexpected result from git cat-file: $head");
 
         my $size = $1;
-        my $rv;
-        my $left = $size;
         $$ref = $size if $ref;
-
-        my $offset = 0;
-        my $buf = '';
-        while ($left > 0) {
-                my $r = read($in, $buf, $left, $offset);
-                defined($r) or fail($self, "read failed: $!");
-                $r == 0 and fail($self, 'exited unexpectedly');
-                $left -= $r;
-                $offset += $r;
-        }
-        $rv = \$buf;
-
-        my $r = read($in, my $lf, 1);
-        defined($r) or fail($self, "read failed: $!");
-        fail($self, 'newline missing after blob') if ($r != 1 || $lf ne "\n");
-
-        $rv;
+        read_cat_in_full($self, $in, $size);
 }
 
 sub batch_prepare ($) { _bidi_pipe($_[0], qw(--batch in out pid)) }
@@ -206,9 +233,15 @@ sub _destroy {
         waitpid($p, 0) if $@; # wait synchronously if not in event loop
 }
 
+sub cat_async_abort ($) {
+        my ($self) = @_;
+        my $inflight = delete $self->{inflight} or die 'BUG: not in async';
+        cleanup($self);
+}
+
 sub fail {
         my ($self, $msg) = @_;
-        cleanup($self);
+        $self->{inflight} ? cat_async_abort($self) : cleanup($self);
         die $msg;
 }
 
@@ -278,6 +311,25 @@ sub pub_urls {
         local_nick($self);
 }
 
+sub cat_async_begin {
+        my ($self) = @_;
+        cleanup($self) if alternates_changed($self);
+        batch_prepare($self);
+        die 'BUG: already in async' if $self->{inflight};
+        $self->{inflight} = [];
+}
+
+sub cat_async ($$$) {
+        my ($self, $oid, $cb) = @_;
+        my $inflight = $self->{inflight} or die 'BUG: not in async';
+        if (scalar(@$inflight) >= MAX_INFLIGHT) {
+                _cat_async_step($self, $inflight, $self->{in});
+        }
+
+        $self->{out}->print($oid, "\n") or fail($self, "write error: $!");
+        push @$inflight, $cb;
+}
+
 sub commit_title ($$) {
         my ($self, $oid) = @_; # PublicInbox::Git, $sha1hex
         my $buf = cat_file($self, $oid) or return;