imap: IDLE: avoid extraneous wakeups, keep-alive

We should not waste memory for IDLE unless it's used on the most
recent inbox slice.  We also need to keep the IDLE connection
alive regardless of $PublicInbox::DS::EXPTIME.

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 0d553da91f9651955234422172facb0ee634bb8a..77e8af12fa9e9e4ac8b47a7b9226b1084df94332 100644 (file)
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -151,7 +151,7 @@ sub cmd_close ($$) {
 
 sub cmd_logout ($$) {
        my ($self, $tag) = @_;
-       delete $self->{logged_in};
+       delete @$self{qw(logged_in -idle_tag)};
        $self->write(\"* BYE logging out\r\n$tag OK Logout done\r\n");
        $self->shutdn; # PublicInbox::DS::shutdn
        undef;
@@ -174,23 +174,63 @@ sub cmd_noop ($$) { "$_[1] OK Noop done\r\n" }
 sub on_inbox_unlock {
        my ($self, $ibx) = @_;
        my $new = $ibx->mm->max;
+       my $uid_end = ($self->{uid_min} // 1) - 1 + UID_BLOCK;
        defined(my $old = $self->{-idle_max}) or die 'BUG: -idle_max unset';
+       $new = $uid_end if $new > $uid_end;
        if ($new > $old) {
                $self->{-idle_max} = $new;
                $self->msg_more("* $_ EXISTS\r\n") for (($old + 1)..($new - 1));
                $self->write(\"* $new EXISTS\r\n");
+       } elsif ($new == $uid_end) { # max exceeded $uid_end
+               # continue idling w/o inotify
+               delete $self->{-idle_max};
+               my $sock = $self->{sock} or return;
+               $ibx->unsubscribe_unlock(fileno($sock));
        }
 }
 
+# called every X minute(s) or so by PublicInbox::DS::later
+my $IDLERS = {};
+my $idle_timer;
+sub idle_tick_all {
+       my $old = $IDLERS;
+       $IDLERS = {};
+       for my $i (values %$old) {
+               next if ($i->{wbuf} || !exists($i->{-idle_tag}));
+               $i->update_idle_time or next;
+               $IDLERS->{fileno($i->{sock})} = $i;
+               $i->write(\"* OK Still here\r\n");
+       }
+       $idle_timer = scalar keys %$IDLERS ?
+                       PublicInbox::DS::later(\&idle_tick_all) : undef;
+}
+
 sub cmd_idle ($$) {
        my ($self, $tag) = @_;
        # IDLE seems allowed by dovecot w/o a mailbox selected *shrug*
        my $ibx = $self->{ibx} or return "$tag BAD no mailbox selected\r\n";
-       $ibx->subscribe_unlock(fileno($self->{sock}), $self);
-       $self->{imapd}->idler_start;
        $self->{-idle_tag} = $tag;
-       $self->{-idle_max} = $ibx->mm->max // 0;
-       "+ idling\r\n"
+       my $max = $ibx->mm->max // 0;
+       my $uid_end = ($self->{uid_min} // 1) - 1 + UID_BLOCK;
+       my $sock = $self->{sock} or return;
+       my $fd = fileno($sock);
+       # only do inotify on most recent slice
+       if ($max < $uid_end) {
+               $ibx->subscribe_unlock($fd, $self);
+               $self->{imapd}->idler_start;
+               $self->{-idle_max} = $max;
+       }
+       $idle_timer //= PublicInbox::DS::later(\&idle_tick_all);
+       $IDLERS->{$fd} = $self;
+       \"+ idling\r\n"
+}
+
+sub stop_idle ($$) {
+       my ($self, $ibx);
+       my $sock = $self->{sock} or return;
+       my $fd = fileno($sock);
+       delete $IDLERS->{$fd};
+       $ibx->unsubscribe_unlock($fd);
 }
 
 sub cmd_done ($$) {
@@ -201,7 +241,7 @@ sub cmd_done ($$) {
                warn "BUG: idle_tag set w/o inbox";
                return "$tag BAD internal bug\r\n";
        };
-       $ibx->unsubscribe_unlock(fileno($self->{sock}));
+       stop_idle($self, $ibx);
        "$idle_tag OK Idle done\r\n";
 }
 
@@ -1185,9 +1225,7 @@ sub busy {
 sub close {
        my ($self) = @_;
        if (my $ibx = delete $self->{ibx}) {
-               if (my $sock = $self->{sock}) {;
-                       $ibx->unsubscribe_unlock(fileno($sock));
-               }
+               stop_idle($self, $ibx);
        }
        $self->SUPER::close; # PublicInbox::DS::close
 }