Don't warn about invalid lines, just debug them. Anchor TS pattern. Unset --sample-time unless --group-by sample.

bin/pt-diskstats

@@ -1934,10 +1934,7 @@ sub parse_diskstats_line {
    my ( $self, $line, $block_size ) = @_;
 
    my @dev_stats = split ' ', $line;
-   if ( @dev_stats != 14 ) {
-      PTDEBUG && _d("Ignoring short diskstats line:", $line);
-      return;
-   }
+   return unless @dev_stats == 14;
 
    my $read_bytes    = $dev_stats[READ_SECTORS]    * $block_size;
    my $written_bytes = $dev_stats[WRITTEN_SECTORS] * $block_size;
@@ -2002,7 +1999,8 @@ sub _parse_and_load_diskstats {
          $new_cur->{$dev} = $dev_stats;
          $self->add_ordered_dev($dev);
       }
-      elsif ( my ($new_ts) = $line =~ /TS\s+([0-9]+(?:\.[0-9]+)?)/ ) {
+      elsif ( my ($new_ts) = $line =~ /^TS\s+([0-9]+(?:\.[0-9]+)?)/ ) {
+         PTDEBUG && _d("Timestamp:", $line);
          if ( $current_ts && %$new_cur ) {
             $self->_handle_ts_line($current_ts, $new_cur, $sample_callback);
             $new_cur = {};
@@ -2010,8 +2008,7 @@ sub _parse_and_load_diskstats {
          $current_ts = $new_ts;
       }
       else {
-         chomp($line);
-         warn "Line $INPUT_LINE_NUMBER: [$line] isn't in the diskstats format";
+         PTDEBUG && _d("Ignoring unknown diskstats line:", $line);
       }
    }
 
@@ -2019,6 +2016,7 @@ sub _parse_and_load_diskstats {
       $self->_handle_ts_line($current_ts, $new_cur, $sample_callback);
       $new_cur = {};
    }
+
    return $INPUT_LINE_NUMBER;
 }
 
@@ -3218,6 +3216,11 @@ sub main {
    $o->get_specs();
    $o->get_opts();
 
+   # --sample-time only applies to --group-by sample.
+   if ( $o->get('group-by') !~ m/sample/i ) {
+      $o->set('sample-time', undef);
+   }
+
    if ( !$o->get('help') ) {
       if ( !$o->get('columns') ) {
          $o->save_error("A regex pattern for --devices must be specified");

lib/Diskstats.pm

@@ -461,10 +461,7 @@ sub parse_diskstats_line {
 
    # Since we assume that device names can't have spaces.
    my @dev_stats = split ' ', $line;
-   if ( @dev_stats != 14 ) {
-      PTDEBUG && _d("Ignoring short diskstats line:", $line);
-      return;
-   }
+   return unless @dev_stats == 14;
 
    my $read_bytes    = $dev_stats[READ_SECTORS]    * $block_size;
    my $written_bytes = $dev_stats[WRITTEN_SECTORS] * $block_size;
@@ -567,7 +564,8 @@ sub _parse_and_load_diskstats {
          $new_cur->{$dev} = $dev_stats;
          $self->add_ordered_dev($dev);
       }
-      elsif ( my ($new_ts) = $line =~ /TS\s+([0-9]+(?:\.[0-9]+)?)/ ) {
+      elsif ( my ($new_ts) = $line =~ /^TS\s+([0-9]+(?:\.[0-9]+)?)/ ) {
+         PTDEBUG && _d("Timestamp:", $line);
          if ( $current_ts && %$new_cur ) {
             $self->_handle_ts_line($current_ts, $new_cur, $sample_callback);
             $new_cur = {};
@@ -575,8 +573,7 @@ sub _parse_and_load_diskstats {
          $current_ts = $new_ts;
       }
       else {
-         chomp($line);
-         warn "Line $INPUT_LINE_NUMBER: [$line] isn't in the diskstats format";
+         PTDEBUG && _d("Ignoring unknown diskstats line:", $line);
       }
    }
 
@@ -584,7 +581,7 @@ sub _parse_and_load_diskstats {
       $self->_handle_ts_line($current_ts, $new_cur, $sample_callback);
       $new_cur = {};
    }
-   # Seems like this could be useful.
+
    return $INPUT_LINE_NUMBER;
 }
 

t/lib/Diskstats.t

@@ -215,7 +215,7 @@ $obj->set_column_regex(qr/./);
 is(
    $header,
    q{%5s %-10s busy},
-   ""
+   "Header"
 );
 
 ($header, $rows, $cols) = $obj->design_print_formats(
@@ -226,7 +226,7 @@ is(
 is(
    $header,
    $all_columns_format,
-   ""
+   "All columns format"
 );
 
 throws_ok( sub { $obj->design_print_formats( columns => {} ) },
@@ -335,10 +335,10 @@ my $output = output(
    stderr => 1,
 );
 
-like(
+is(
    $output,
-   qr/isn't in the diskstats format/,
-   "->parse_from and friends fail on malformed data"
+   "",
+   "Doesn't die parsing unknown line"
 );
 
 # ############################################################################