From: David Bremner <bremner@debian.org>

In the case of large changes to the database from git, one of main
current bottlenecks is the large number of execs of notmuch tag. This
avoids that by using use the batch tagging facilities as of notmuch
0.15.

We use "spawn" directly rather than inventing a "notmuch_pipe", since
it seems the only place we need to pipe to notmuch so far.
---

This is only lightly tested; please make sure you have backups of your
database.

I'm not 100% sure about the indentation. No doubt Tomi will let me
know if it can be improved.

 contrib/nmbug/nmbug |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/contrib/nmbug/nmbug b/contrib/nmbug/nmbug
index f003ef9..c66c526 100755
--- a/contrib/nmbug/nmbug
+++ b/contrib/nmbug/nmbug
@@ -270,17 +270,22 @@ sub do_sync {
     $D_action = '-';
   }
 
-  foreach my $pair (@{$status->{added}}) {
+  my $notmuch = spawn ({}, '|-', qw/notmuch tag --batch/)
+      or die 'notmuch tag --batch';
 
-    notmuch ('tag', $A_action.$TAGPREFIX.$pair->{tag},
-	     'id:'.$pair->{id});
+  foreach my $pair (@{$status->{added}}) {
+    print $notmuch $A_action.$TAGPREFIX.$pair->{tag}, " -- ",
+      'id:'.$pair->{id};
   }
 
   foreach my $pair (@{$status->{deleted}}) {
-    notmuch ('tag', $D_action.$TAGPREFIX.$pair->{tag},
-	     'id:'.$pair->{id});
+    print $notmuch $D_action.$TAGPREFIX.$pair->{tag},
+      'id:'.$pair->{id};
   }
 
+  unless (close $notmuch) {
+    die "'notmuch tag --batch' exited with nonzero value\n";
+  }
 }
 
 
-- 
1.7.10.4