sub zflush {} # overridden by NNTPdeflate and IMAPdeflate
+sub long_response_done {} # overridden by Net::NNTP
+
+sub long_step {
+ my ($self) = @_;
+ # wbuf is unset or empty, here; {long} may add to it
+ my ($fd, $cb, $t0, @args) = @{$self->{long_cb}};
+ my $more = eval { $cb->($self, @args) };
+ if ($@ || !$self->{sock}) { # something bad happened...
+ delete $self->{long_cb};
+ my $elapsed = now() - $t0;
+ $@ and $self->err("%s during long response[$fd] - %0.6f",
+ $@, $elapsed);
+ $self->out(" deferred[$fd] aborted - %0.6f", $elapsed);
+ $self->close;
+ } elsif ($more) { # $self->{wbuf}:
+ # control passed to ibx_async_cat if $more == \undef
+ requeue_once($self) if !ref($more);
+ } else { # all done!
+ delete $self->{long_cb};
+ $self->long_response_done;
+ my $elapsed = now() - $t0;
+ my $fd = fileno($self->{sock});
+ $self->out(" deferred[$fd] done - %0.6f", $elapsed);
+ my $wbuf = $self->{wbuf}; # do NOT autovivify
+ requeue($self) unless $wbuf && @$wbuf;
+ }
+}
+
+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. wbuf may be populated by $cb,
+ # no need to rearm if so: (push returns new size of array)
+ requeue($self) if push(@{$self->{wbuf}}, \&long_step) == 1;
+}
+
+sub long_response ($$;@) {
+ my ($self, $cb, @args) = @_; # cb returns true if more, false if done
+ my $sock = $self->{sock} or return;
+ # make sure we disable reading during a long response,
+ # clients should not be sending us stuff and making us do more
+ # work while we are stream a response to them
+ $self->{long_cb} = [ fileno($sock), $cb, now(), @args ];
+ long_step($self); # kick off!
+ undef;
+}
+
sub dwaitpid ($;$$) {
my ($pid, $cb, $arg) = @_;
if ($in_loop) {