#!/opt/local/bin/perl
# Script to dump the ddl_log.log file created in mysql during ddl operations.
# Mainly used by the partitioning function introduced in 5.1
#
# Structure of the file
# Offsets in each entry
# DDL_LOG_ENTRY_TYPE_POS 0
# DDL_LOG_ACTION_TYPE_POS 1
# DDL_LOG_PHASE_POS 2
# DDL_LOG_NEXT_ENTRY_POS 4
# DDL_LOG_NAME_POS 8

# Offsets in first entry (the header)
# DDL_LOG_NUM_ENTRY_POS 0
# DDL_LOG_NAME_LEN_POS 4
# DDL_LOG_IO_SIZE_POS 8

# Header
# offset size  Description
# 0      4     Number of entries in the ddl log
# 4      4     FN_LEN - Maximum length of name strings in the log
#              (fixed/null padded)
# 8      4     IO_SIZE - Fixed size of each entry

# First byte in each entry
# 'e' - DDL_LOG_EXECUTE_CODE:
#       This is a code that indicates that this is a log entry to
#       be executed, from this entry a linked list of log entries
#       can be found and executed.
# 'l' - DDL_LOG_ENTRY_CODE:
#       An entry to be executed in a linked list from an execute log
#       entry.
# 'i' - DDL_IGNORE_LOG_ENTRY_CODE:
#       An entry that is to be ignored

# Second byte in each entry
# The type of action that a DDL_LOG_ENTRY_CODE entry is to
# perform.
# 'd' - DDL_LOG_DELETE_ACTION:
#       Delete an entity
# 'r' - DDL_LOG_RENAME_ACTION:
#       Rename an entity
# 's' - DDL_LOG_REPLACE_ACTION:
#       Rename an entity after removing the previous entry with the
#       new name, that is replace this entry.

# First real entry
# offset size  Description
# 4096   1     DDL_LOG_ENTRY_TYPE - 'e'/'l'/'i'
# 4097   1     DDL_LOG_ACTION_TYPE - 'd'/'r'/'s'
# 4098   1     PHASE (REPLACE have two phases, remove the target then rename)
# 4099   1     UNUSED - only for alignment
# 5000   4     Next entry pos - entry number of next linked entry
# 5004   4     Internal table/partition name
# 

my $ddl_log_filename = $ARGV[0];
my $num_of_entries;
my $name_length;
my $block_length;
my $raw_data;
open FH, $ddl_log_filename or die "Could not open $ddl_log_filename";
# read header to get sizes of names and blocks
read FH, $raw_data, 12 or die "Failed to read header";
($num_of_entries, $name_length, $block_length) = unpack("VVV", $raw_data) or die "Failed to unpack header";
print "Header: Num entries: $num_of_entries Name length: $name_length Block length $block_length\n";

my $curr_pos = $block_length;
my $curr_entry = 1;
my $entry_type;
my $entry_action;
my $entry_phase;
my $entry_next;
my $entry_name;
my $entry_from_name;
my $entry_handler_name;

for (my $i= 1; $i < $num_of_entries ; $i++)
{
  seek (FH, $block_length * $i, 0) or die "Failed to seek to entry $i";
  read FH, $raw_data, $block_length or die "Failed to read entry $i";
  ($entry_type, $entry_action, $entry_phase, undef, $entry_next, $entry_name, $entry_from_name, $entry_handler_name) = unpack("aaaaVZ$name_lengthZ$name_lengthZ$name_length", $raw_data);
  print "Entry $i type $entry_type action $entry_action next $entry_next\n  name $entry_name\n";
  if ($entry_from_name ne "")
  {
    print "  from name $entry_from_name\n";
  }
  if ($entry_handler_name ne "")
  {
    print "  handler name $entry_handler_name\n";
  }
  if ($entry_type eq "e") {
    print_execute($i);
  } else {
    print "not 'e' entry ($entry_type)\n";
  }
}

sub print_execute()
{
  my ($entry_nr) = @_;
  seek (FH, $block_length * $entry_nr, 0) or die "Failed to seek to entry $entry_nr";
  read FH, $raw_data, $block_length or die "Failed to read entry $entry_nr";
  ($entry_type, $entry_action, $entry_phase, undef, $entry_next, $entry_name, $entry_from_name, $entry_handler_name) = unpack("aaaaVZ$name_lengthZ$name_lengthZ$name_length", $raw_data);
  if ($entry_type eq "i") {
    print "IGNORE Entry $entry_nr type $entry_type action $entry_action next $entry_next\n  name $entry_name\n";
    if ($entry_from_name ne "")
    {
      print "  from name $entry_from_name\n";
    }
    if ($entry_handler_name ne "")
    {
      print "  handler name $entry_handler_name\n";
    }
  } elsif ($entry_type eq "e") {
    print "LOG Entry $entry_nr type $entry_type action $entry_action next $entry_next\n  name $entry_name\n";
    if ($entry_from_name ne "")
    {
      print "  from name $entry_from_name\n";
    }
    if ($entry_handler_name ne "")
    {
      print "  handler name $entry_handler_name\n";
    }
  } else {
    print "UNKNOWN Entry $entry_nr type $entry_type action $entry_action next $entry_next\n  name $entry_name\n";
  }
  print_execute($entry_next);
}
#while (($curr_pos / $block_length) <= $num_of_entries)
#{
#seek (FH, $curr_pos, 0) or die "Failed to seek to $curr_pos (entry $curr_entry)";
#read FH, $raw_data, $block_length or die "Failed to read entry $curr_entry";
#($entry_type, $entry_action, $entry_phase, undef, $entry_next, $entry_name, $entry_from_name, $entry_handler_name) = unpack("aaaaVZ$name_lengthZ$name_lengthZ$name_length", $raw_data);
#print "Entry $curr_entry type $entry_type action $entry_action next $entry_next\n  name $entry_name\n";
#if ($entry_from_name ne "")
##{
##print "  from name $entry_from_name\n";
#}
#if ($entry_handler_name ne "")
#{
#print "  handler name $entry_handler_name\n";
#}
#$curr_entry = $entry_next;
#$curr_pos = $entry_entry * $block_length;
#}