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_OFFSET =

Offset of the header within the log block.

0
TRAILER_OFFSET =

Offset of the trailer within ths log block.

BLOCK_SIZE - 4
HEADER_FLUSH_BIT_MASK =

Mask used to get the flush bit in the header.

0x80000000
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 22

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 31

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

#dump ⇒ Object

Dump the contents of a log block for debugging purposes.



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# File 'lib/innodb/log_block.rb', line 137

def dump
  puts
  puts "header:"
  pp header

  puts
  puts "trailer:"
  pp trailer

  puts
  puts "record:"
  pp first_record_preamble
end

#first_record_preamble ⇒ Object

Return a preamble of the first record in this block.



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# File 'lib/innodb/log_block.rb', line 115

def first_record_preamble
  return nil unless header[:first_rec_group] > 0
  cursor(header[:first_rec_group]).name("header") do |c|
    type_and_flag = c.name("type") { c.get_uint8 }
    type = type_and_flag & RECORD_TYPE_MASK
    type = RECORD_TYPES[type] || type
    single_record = (type_and_flag & SINGLE_RECORD_MASK) > 0
    case type
    when :MULTI_REC_END, :DUMMY_RECORD
      { :type => type }
    else
      {
        :type           => type,
        :single_record  => single_record,
        :space          => c.name("space") { c.get_ic_uint32 },
        :page_number    => c.name("page_number") { c.get_ic_uint32 },
      }
    end
  end
end

#header ⇒ Object

Return the log block header.



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

def header
  @header ||= cursor(HEADER_OFFSET).name("header") do |c|
    {
      :flush => c.name("flush") {
        c.peek { (c.get_uint32 & HEADER_FLUSH_BIT_MASK) > 0 }
      },
      :block_number => c.name("block_number") {
        c.get_uint32 & ~HEADER_FLUSH_BIT_MASK
      },
      :data_length      => c.name("data_length")     { c.get_uint16 },
      :first_rec_group  => c.name("first_rec_group") { c.get_uint16 },
      :checkpoint_no    => c.name("checkpoint_no")   { c.get_uint32 },
    }
  end
end

#trailer ⇒ Object

Return the log block trailer.



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# File 'lib/innodb/log_block.rb', line 53

def trailer
  @trailer ||= cursor(TRAILER_OFFSET).name("trailer") do |c|
    {
      :checksum => c.name("checksum") { c.get_uint32 },
    }
  end
end