Allow initial values to be zero for ReplicaLagLimiter::new(). Return 1/0/death from ReplicaLagLimiter::wait().

lib/ReplicaLagLimiter.pm

@@ -57,7 +57,7 @@ sub new {
    my ( $class, %args ) = @_;
    my @required_args = qw(spec slaves get_lag initial_n initial_t target_t);
    foreach my $arg ( @required_args ) {
-      die "I need a $arg argument" unless $args{$arg};
+      die "I need a $arg argument" unless defined $args{$arg};
    }
    my ($spec) = @args{@required_args};
 
@@ -146,7 +146,7 @@ sub update {
 #   Progress - <Progress> object to report waiting
 #
 # Returns:
-#   True if all slaves catch up before timeout, else die unless continue is true
+#   1 if all slaves catch up before timeout, else 0 if continue=yes, else die.
 sub wait {
    my ( $self, %args ) = @_;
    my @required_args = qw();
@@ -196,13 +196,19 @@ sub wait {
          $slave = $slaves->[++$slave_no];
       }
    }
-   if ( $slave_no < @$slaves && $self->{continue} eq 'no' ) {
+   if ( $slave_no < @$slaves ) {
-      die "Timeout waiting for replica " . $slaves->[$slave_no]->{dsn}->{n}
+      if ( $self->{continue} eq 'no' ) {
-        . " to catch up\n";
+         die "Timeout waiting for replica " . $slaves->[$slave_no]->{dsn}->{n}
+            . " to catch up\n";
+      }
+      else {
+         MKDEBUG && _d('Some slave are not caught up');
+         return 0; # not ready
+      }
    }
 
    MKDEBUG && _d('All slaves caught up');
-   return 1;
+   return 1; # ready
 }
 
 sub _d {

t/lib/NibbleIterator.t

@@ -38,7 +38,7 @@ if ( !$dbh ) {
    plan skip_all => 'Cannot connect to sandbox master';
 }
 else {
-   plan tests => 20;
+   plan tests => 21;
 }
 
 my $q  = new Quoter();
@@ -447,6 +447,27 @@ is_deeply(
    "Change chunk size while nibbling"
 ) or print STDERR Dumper(\@rows);
 
+# ############################################################################
+# Nibble one row at a time.
+# ############################################################################
+$ni = make_nibble_iter(
+   sql_file  => "a-z.sql",
+   db        => 'test',
+   tbl       => 't',
+   argv      => [qw(--databases test --chunk-size 1)],
+);
+
+@rows = ();
+while (my $row = $ni->next()) {
+   push @rows, @$row;
+}
+
+is_deeply(
+   \@rows,
+   [ ('a'..'z') ],
+   "Nibble by 1 row"
+);
+
 # #############################################################################
 # Done.
 # #############################################################################

t/lib/ReplicaLagLimiter.t

@@ -197,8 +197,8 @@ $rll = new ReplicaLagLimiter(
 @lag    = (5, 0, 0);
 is(
    $rll->wait(),
-   1,
+   0,
-   "wait() returns 1 despite timeout if continue=yes"
+   "wait() returns 0 if timeout and continue=yes"
 );
 
 # #############################################################################