imap: use git-cat-file asynchronously

This ought to improve overall performance with multiple clients.
Single client performance suffers a tiny bit due to extra
syscall overhead from epoll.

This also makes the existing async interface easier-to-use,
since calling cat_async_begin is no longer required.

1 files changed, 26 insertions, 23 deletions

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 39667199..2282e3ce 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -21,8 +21,10 @@ use PublicInbox::Eml;
 use PublicInbox::EmlContentFoo qw(parse_content_disposition);
 use PublicInbox::DS qw(now);
 use PublicInbox::Syscall qw(EPOLLIN EPOLLONESHOT);
+use PublicInbox::GitAsyncCat;
 use Text::ParseWords qw(parse_line);
 use Errno qw(EAGAIN);
+
 my $Address;
 for my $mod (qw(Email::Address::XS Mail::Address)) {
         eval "require $mod" or next;
@@ -367,14 +369,30 @@ EOF
         \$ret;
 }
 
-sub uid_fetch_cb { # called by git->cat_async
+sub requeue_once ($) {
+        my ($self) = @_;
+        # COMPRESS users all share the same DEFLATE context.
+        # Flush it here to ensure clients don't see
+        # each other's data
+        $self->zflush;
+
+        # no recursion, schedule another call ASAP,
+        # but only after all pending writes are done.
+        # autovivify wbuf:
+        my $new_size = push(@{$self->{wbuf}}, \&long_step);
+
+        # wbuf may be populated by $cb, no need to rearm if so:
+        $self->requeue if $new_size == 1;
+}
+
+sub uid_fetch_cb { # called by git->cat_async via git_async_msg
         my ($bref, $oid, $type, $size, $fetch_m_arg) = @_;
         my ($self, undef, $ibx, undef, undef, $msgs, $want) = @$fetch_m_arg;
         my $smsg = shift @$msgs or die 'BUG: no smsg';
         if (!defined($oid)) {
                 # it's possible to have TOCTOU if an admin runs
                 # public-inbox-(edit|purge), just move onto the next message
-                return unless defined $want->{-seqno};
+                return requeue_once($self) unless defined $want->{-seqno};
                 $bref = dummy_message($smsg->{num}, $ibx);
         } else {
                 $smsg->{blob} eq $oid or die "BUG: $smsg->{blob} != $oid";
@@ -420,6 +438,7 @@ sub uid_fetch_cb { # called by git->cat_async
                 partial_emit($self, $partial, $eml);
         }
         $self->msg_more(")\r\n");
+        requeue_once($self);
 }
 
 sub uid_fetch_m { # long_response
@@ -432,11 +451,7 @@ sub uid_fetch_m { # long_response
                 }
                 $$beg = $msgs->[-1]->{num} + 1;
         }
-        my $git = $ibx->git;
-        $git->cat_async_begin; # TODO: actually make async
-        $git->cat_async($msgs->[0]->{blob}, \&uid_fetch_cb, \@_);
-        $git->cat_async_wait;
-        1;
+        git_async_msg($ibx, $msgs->[0], \&uid_fetch_cb, \@_);
 }
 
 sub cmd_status ($$$;@) {
@@ -677,20 +692,17 @@ sub seq_fetch_m { # long_response
         my $seq = $want->{-seqno}++;
         my $cur_num = $msgs->[0]->{num};
         if ($cur_num == $seq) { # as expected
-                my $git = $ibx->git;
-                $git->cat_async_begin; # TODO: actually make async
-                $git->cat_async($msgs->[0]->{blob}, \&uid_fetch_cb, \@_);
-                $git->cat_async_wait;
+                git_async_msg($ibx, $msgs->[0], \&uid_fetch_cb, \@_);
         } elsif ($cur_num > $seq) {
                 # send dummy messages until $seq catches up to $cur_num
                 my $smsg = bless { num => $seq, ts => 0 }, 'PublicInbox::Smsg';
                 unshift @$msgs, $smsg;
                 my $bref = dummy_message($seq, $ibx);
                 uid_fetch_cb($bref, undef, undef, undef, \@_);
+                $smsg; # blessed response since uid_fetch_cb requeues
         } else { # should not happen
                 die "BUG: cur_num=$cur_num < seq=$seq";
         }
-        1; # more messages on the way
 }
 
 sub cmd_fetch ($$$;@) {
@@ -810,17 +822,8 @@ sub long_step {
         } elsif ($more) { # $self->{wbuf}:
                 $self->update_idle_time;
 
-                # COMPRESS users all share the same DEFLATE context.
-                # Flush it here to ensure clients don't see
-                # each other's data
-                $self->zflush;
-
-                # no recursion, schedule another call ASAP, but only after
-                # all pending writes are done.  autovivify wbuf:
-                my $new_size = push(@{$self->{wbuf}}, \&long_step);
-
-                # wbuf may be populated by $cb, no need to rearm if so:
-                $self->requeue if $new_size == 1;
+                # control passed to $more may be a GitAsyncCat object
+                requeue_once($self) if !ref($more);
         } else { # all done!
                 delete $self->{long_cb};
                 my $elapsed = now() - $t0;