v2writable: support "barrier" operation to avoid reforking

Stopping and starting a bunch of processes to look up duplicates
or removals is inefficient.  Take advantage of checkpointing
in "git fast-import" and transactions in Xapian and SQLite.

1 files changed, 9 insertions, 1 deletions

diff --git a/lib/PublicInbox/Import.pm b/lib/PublicInbox/Import.pm
index 664bec69..8406c9e2 100644
--- a/lib/PublicInbox/Import.pm
+++ b/lib/PublicInbox/Import.pm
@@ -133,7 +133,6 @@ sub check_remove_v1 {
         (undef, $cur);
 }
 
-# used for v2 (maybe)
 sub checkpoint {
         my ($self) = @_;
         return unless $self->{pid};
@@ -141,6 +140,15 @@ sub checkpoint {
         undef;
 }
 
+sub progress {
+        my ($self, $msg) = @_;
+        return unless $self->{pid};
+        print { $self->{out} } "progress $msg\n" or wfail;
+        $self->{in}->getline eq "progress $msg\n" or die
+                "progress $msg not received\n";
+        undef;
+}
+
 # used for v2
 sub get_mark {
         my ($self, $mark) = @_;