Class: Innodb::LogBlock

Inherits:
Object
  • Object
show all
Defined in:
lib/innodb/log_block.rb

Overview

An InnoDB transaction log block.

Constant Summary collapse

BLOCK_SIZE =

Log blocks are fixed-length at 512 bytes in InnoDB.

512
HEADER_SIZE = 
12
HEADER_START = 
0
TRAILER_SIZE = 
4
TRAILER_START = 
BLOCK_SIZE - TRAILER_SIZE
RECORD_START = 
HEADER_START + HEADER_SIZE
RECORD_TYPES =

The constants used by InnoDB for identifying different log record types.

{
  1  => :MLOG_1BYTE,
  2  => :MLOG_2BYTE,
  4  => :MLOG_4BYTE,
  8  => :MLOG_8BYTE,
  9  => :REC_INSERT,
  10 => :REC_CLUST_DELETE_MARK,
  11 => :REC_SEC_DELETE_MARK,
  13 => :REC_UPDATE_IN_PLACE,
  14 => :REC_DELETE,
  15 => :LIST_END_DELETE,
  16 => :LIST_START_DELETE,
  17 => :LIST_END_COPY_CREATED,
  18 => :PAGE_REORGANIZE,
  19 => :PAGE_CREATE,
  20 => :UNDO_INSERT,
  21 => :UNDO_ERASE_END,
  22 => :UNDO_INIT,
  23 => :UNDO_HDR_DISCARD,
  24 => :UNDO_HDR_REUSE,
  25 => :UNDO_HDR_CREATE,
  26 => :REC_MIN_MARK,
  27 => :IBUF_BITMAP_INIT,
  28 => :LSN,
  29 => :INIT_FILE_PAGE,
  30 => :WRITE_STRING,
  31 => :MULTI_REC_END,
  32 => :DUMMY_RECORD,
  33 => :FILE_CREATE,
  34 => :FILE_RENAME,
  35 => :FILE_DELETE,
  36 => :COMP_REC_MIN_MARK,
  37 => :COMP_PAGE_CREATE,
  38 => :COMP_REC_INSERT,
  39 => :COMP_REC_CLUST_DELETE_MARK,
  40 => :COMP_REC_SEC_DELETE_MARK,
  41 => :COMP_REC_UPDATE_IN_PLACE,
  42 => :COMP_REC_DELETE,
  43 => :COMP_LIST_END_DELETE,
  44 => :COMP_LIST_START_DELETE,
  45 => :COMP_LIST_END_COPY_CREATE,
  46 => :COMP_PAGE_REORGANIZE,
  47 => :FILE_CREATE2,
  48 => :ZIP_WRITE_NODE_PTR,
  49 => :ZIP_WRITE_BLOB_PTR,
  50 => :ZIP_WRITE_HEADER,
  51 => :ZIP_PAGE_COMPRESS,
}
SINGLE_RECORD_MASK = 
0x80
RECORD_TYPE_MASK = 
0x7f

Instance Method Summary collapse

Constructor Details

#initialize(buffer) ⇒ LogBlock

Initialize a log block by passing in a 512-byte buffer containing the raw log block contents.



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# File 'lib/innodb/log_block.rb', line 36

def initialize(buffer)
  unless buffer.size == BLOCK_SIZE
    raise "Log block buffer provided was not #{BLOCK_SIZE} bytes" 
  end

  @buffer = buffer
end

Instance Method Details

#cursor(offset) ⇒ Object

Return an Innodb::Cursor object positioned at a specific offset.



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# File 'lib/innodb/log_block.rb', line 51

def cursor(offset)
  Innodb::Cursor.new(self, offset)
end

#data(offset, length) ⇒ Object

A helper function to return bytes from the log block buffer based on offset and length, both in bytes.



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# File 'lib/innodb/log_block.rb', line 46

def data(offset, length)
  @buffer[offset...(offset + length)]
end

#dump ⇒ Object

Dump the contents of a log block for debugging purposes.



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# File 'lib/innodb/log_block.rb', line 169

def dump
  puts
  puts "header:"
  pp header

  puts
  puts "trailer:"
  pp trailer

  puts
  puts "record:"
  pp record
end

#header ⇒ Object

Return the log block header.



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# File 'lib/innodb/log_block.rb', line 56

def header
  @header ||= begin
    c = cursor(HEADER_START)
    {
      :block            => c.get_uint32 & (2**31-1),
      :data_length      => c.get_uint16,
      :first_rec_group  => c.get_uint16,
      :checkpoint_no    => c.get_uint32,
    }
  end
end

#record ⇒ Object

Return the log record. (This is mostly unimplemented.)



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# File 'lib/innodb/log_block.rb', line 149

def record
  @record ||= begin
    if header[:first_rec_group] != 0
      c = cursor(header[:first_rec_group])
      type_and_flag = c.get_uint8
      type = type_and_flag & RECORD_TYPE_MASK
      type = RECORD_TYPES[type] || type
      single_record = (type_and_flag & SINGLE_RECORD_MASK) > 0
      {
        :type           => type,
        :single_record  => single_record,
        :content        => record_content(type, c.position),
        :space          => c.get_ic_uint32,
        :page_number    => c.get_ic_uint32,
      }
    end
  end
end

#record_content(record_type, offset) ⇒ Object

Return the log record contents. (This is mostly unimplemented.)



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# File 'lib/innodb/log_block.rb', line 129

def record_content(record_type, offset)
  c = cursor(offset)
  case record_type
  when :MLOG_1BYTE
    c.get_uint8
  when :MLOG_2BYTE
    c.get_uint16
  when :MLOG_4BYTE
    c.get_uint32
  when :MLOG_8BYTE
    c.get_uint64
  when :UNDO_INSERT
  when :COMP_REC_INSERT
  end
end

#trailer ⇒ Object

Return the log block trailer.



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# File 'lib/innodb/log_block.rb', line 69

def trailer
  @trailer ||= begin
    c = cursor(TRAILER_START)
    {
      :checksum => c.get_uint32,
    }
  end
end