Added pause to NibbleIterator

bin/pt-online-schema-change

@@ -5529,6 +5529,8 @@ sub new {
    $self->{have_rows}  = 0;
    $self->{rowno}      = 0;
    $self->{oktonibble} = 1;
+   $self->{pause_file} = $nibble_params->{pause_file};
+   $self->{sleep}      = $args{sleep} || 60;
 
    return bless $self, $class;
 }
@@ -5567,6 +5569,24 @@ sub next {
 
    NIBBLE:
    while ( $self->{have_rows} || $self->_next_boundaries() ) {
+
+      if ($self->{pause_file}) {
+         while(-f $self->{pause_file}) {
+            print "Sleeping $self->{sleep} seconds because $self->{pause_file} exists\n";
+            my $dbh = $self->{Cxn}->dbh();
+            if ( !$dbh || !$dbh->ping() ) {
+               eval { $dbh = $self->{Cxn}->connect() }; # connect or die trying
+               if ( $EVAL_ERROR ) {
+                  chomp $EVAL_ERROR;
+                  die "Lost connection to " . $self->{Cxn}->name() . " while waiting for "
+                  . "replica lag ($EVAL_ERROR)\n";
+               }
+            }
+            $dbh->do("SELECT 'nibble iterator keepalive'");
+            sleep($self->{sleep});
+         }
+      }
+  
       if ( !$self->{have_rows} ) {
          $self->{nibbleno}++;
          PTDEBUG && _d('Nibble:', $self->{nibble_sth}->{Statement}, 'params:',
@@ -5596,6 +5616,7 @@ sub next {
       }
       $self->{rowno}     = 0;
       $self->{have_rows} = 0;
+      
    }
 
    PTDEBUG && _d('Done nibbling');
@@ -5731,10 +5752,13 @@ sub can_nibble {
       die "There is no good index and the table is oversized.";
    }
 
+   my $pause_file = ($o->has('pause-file') && $o->get('pause-file')) || undef;
+   
    return {
       row_est     => $row_est,      # nibble about this many rows
       index       => $index,        # using this index
       one_nibble  => $one_nibble,   # if the table fits in one nibble/chunk
+      pause_file  => $pause_file,
    };
 }
 
@@ -11723,6 +11747,12 @@ short form: -p; type: string
 Password to use when connecting.
 If password contains commas they must be escaped with a backslash: "exam\,ple"
 
+=item --pause-file
+
+type: string 
+
+Execution will be paused while the file specified by this param exists.
+
 =item --pid
 
 type: string

bin/pt-table-checksum

@@ -6336,6 +6336,8 @@ sub new {
    $self->{have_rows}  = 0;
    $self->{rowno}      = 0;
    $self->{oktonibble} = 1;
+   $self->{pause_file} = $nibble_params->{pause_file};
+   $self->{sleep}      = $args{sleep} || 60;
 
    return bless $self, $class;
 }
@@ -6374,6 +6376,24 @@ sub next {
 
    NIBBLE:
    while ( $self->{have_rows} || $self->_next_boundaries() ) {
+
+      if ($self->{pause_file}) {
+         while(-f $self->{pause_file}) {
+            print "Sleeping $self->{sleep} seconds because $self->{pause_file} exists\n";
+            my $dbh = $self->{Cxn}->dbh();
+            if ( !$dbh || !$dbh->ping() ) {
+               eval { $dbh = $self->{Cxn}->connect() }; # connect or die trying
+               if ( $EVAL_ERROR ) {
+                  chomp $EVAL_ERROR;
+                  die "Lost connection to " . $self->{Cxn}->name() . " while waiting for "
+                  . "replica lag ($EVAL_ERROR)\n";
+               }
+            }
+            $dbh->do("SELECT 'nibble iterator keepalive'");
+            sleep($self->{sleep});
+         }
+      }
+  
       if ( !$self->{have_rows} ) {
          $self->{nibbleno}++;
          PTDEBUG && _d('Nibble:', $self->{nibble_sth}->{Statement}, 'params:',
@@ -6403,6 +6423,7 @@ sub next {
       }
       $self->{rowno}     = 0;
       $self->{have_rows} = 0;
+      
    }
 
    PTDEBUG && _d('Done nibbling');
@@ -6538,10 +6559,13 @@ sub can_nibble {
       die "There is no good index and the table is oversized.";
    }
 
+   my $pause_file = ($o->has('pause-file') && $o->get('pause-file')) || undef;
+   
    return {
       row_est     => $row_est,      # nibble about this many rows
       index       => $index,        # using this index
       one_nibble  => $one_nibble,   # if the table fits in one nibble/chunk
+      pause_file  => $pause_file,
    };
 }
 
@@ -12397,6 +12421,12 @@ short form: -p; type: string; group: Connection
 Password to use when connecting.
 If password contains commas they must be escaped with a backslash: "exam\,ple"
 
+=item --pause-file
+
+type: string 
+
+Execution will be paused while the file specified by this param exists.
+
 =item --pid
 
 type: string

lib/NibbleIterator.pm

@@ -263,6 +263,8 @@ sub new {
    $self->{have_rows}  = 0;
    $self->{rowno}      = 0;
    $self->{oktonibble} = 1;
+   $self->{pause_file} = $nibble_params->{pause_file};
+   $self->{sleep}      = $args{sleep} || 60;
 
    return bless $self, $class;
 }
@@ -304,6 +306,24 @@ sub next {
    # If there's another nibble, fetch the rows within it.
    NIBBLE:
    while ( $self->{have_rows} || $self->_next_boundaries() ) {
+
+      if ($self->{pause_file}) {
+         while(-f $self->{pause_file}) {
+            print "Sleeping $self->{sleep} seconds because $self->{pause_file} exists\n";
+            my $dbh = $self->{Cxn}->dbh();
+            if ( !$dbh || !$dbh->ping() ) {
+               eval { $dbh = $self->{Cxn}->connect() }; # connect or die trying
+               if ( $EVAL_ERROR ) {
+                  chomp $EVAL_ERROR;
+                  die "Lost connection to " . $self->{Cxn}->name() . " while waiting for "
+                  . "replica lag ($EVAL_ERROR)\n";
+               }
+            }
+            $dbh->do("SELECT 'nibble iterator keepalive'");
+            sleep($self->{sleep});
+         }
+      }
+  
       # If no rows, then we just got the next boundaries, which start
       # the next nibble.
       if ( !$self->{have_rows} ) {
@@ -341,6 +361,7 @@ sub next {
       }
       $self->{rowno}     = 0;
       $self->{have_rows} = 0;
+      
    }
 
    PTDEBUG && _d('Done nibbling');
@@ -493,10 +514,13 @@ sub can_nibble {
 
    # The table can be nibbled if this point is reached, else we would have
    # died earlier.  Return some values about nibbling the table.
+   my $pause_file = ($o->has('pause-file') && $o->get('pause-file')) || undef;
+   
    return {
       row_est     => $row_est,      # nibble about this many rows
       index       => $index,        # using this index
       one_nibble  => $one_nibble,   # if the table fits in one nibble/chunk
+      pause_file  => $pause_file,
    };
 }
 

t/lib/NibbleIterator.t

@@ -23,6 +23,7 @@ use RowChecksum;
 use NibbleIterator;
 use Cxn;
 use PerconaTest;
+use File::Temp qw/ tempfile /;
 
 use constant PTDEBUG => $ENV{PTDEBUG} || 0;
 
@@ -92,6 +93,8 @@ sub make_nibble_iter {
       resume      => $args{resume},
       order_by    => $args{order_by},
       comments    => $args{comments},
+      pause_file  => $o->get('pause-file'),
+      sleep       => $args{sleep} || 60,
       %common_modules,
    );
 
@@ -355,6 +358,29 @@ is(
    "init callbacks can stop nibbling"
 );
 
+my ($fh, $filename) = tempfile();
+system ("sleep 3 && rm $filename &");
+
+$ni = make_nibble_iter(
+   db       => 'sakila',
+   tbl      => 'payment',
+   sleep    => 3,
+   argv     => [qw(--databases sakila --tables payment --chunk-size 100 --pause-file ), $filename],
+);
+
+$output = output(
+   sub {
+      for (1..8) { $ni->next() }
+   },
+);
+
+like(
+   $output,
+   qr/Sleeping 3 seconds because/,
+   "nibbles paused"
+);
+
+
 # ############################################################################
 # Nibble a larger table by numeric pk id
 # ############################################################################