Class: Innodb::Log

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

Overview

An InnoDB transaction log file.

Constant Summary collapse

HEADER_SIZE = 
4 * Innodb::LogBlock::BLOCK_SIZE
HEADER_START = 
0
DATA_START = 
HEADER_START + HEADER_SIZE

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file) ⇒ Log

Open a log file.



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# File 'lib/innodb/log.rb', line 21

def initialize(file)
  @name = file
  File.open(@name) do |log|
    @size = log.stat.size
    @blocks = ((@size - DATA_START) / Innodb::LogBlock::BLOCK_SIZE)
  end
end

Instance Attribute Details

#blocks ⇒ Object (readonly)

Returns the value of attribute blocks.



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# File 'lib/innodb/log.rb', line 29

def blocks
  @blocks
end

Instance Method Details

#block(block_number) ⇒ Object

Return a log block with a given block number as an InnoDB::LogBlock object. Blocks are numbered after the log file header, starting from 0.



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# File 'lib/innodb/log.rb', line 33

def block(block_number)
  offset = DATA_START + (block_number.to_i * Innodb::LogBlock::BLOCK_SIZE)
  return nil unless offset < @size
  return nil unless (offset + Innodb::LogBlock::BLOCK_SIZE) <= @size
  File.open(@name) do |log|
    log.seek(offset)
    block_data = log.read(Innodb::LogBlock::BLOCK_SIZE)
    Innodb::LogBlock.new(block_data)
  end
end

#each_block ⇒ Object

Iterate through all log blocks, returning the block number and an InnoDB::LogBlock object for each block.



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

def each_block
  (0...@blocks).each do |block_number|
    current_block = block(block_number)
    yield block_number, current_block if current_block
  end
end