Class: Innodb::Space

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

Overview

An InnoDB space file, which can be either a multi-table ibdataN file or a single-table "innodb_file_per_table" .ibd file.

Constant Summary collapse

DEFAULT_PAGE_SIZE =

InnoDB's default page size is 16KiB.

16384
SYSTEM_SPACE_PAGE_MAP =

A map of InnoDB system space fixed-allocation pages. This can be used to check whether a space is a system space or not, as non-system spaces will not match this pattern.

{
  0 => :FSP_HDR,
  1 => :IBUF_BITMAP,
  2 => :INODE,
  3 => :SYS,
  4 => :INDEX,
  5 => :TRX_SYS,
  6 => :SYS,
  7 => :SYS,
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file, page_size = nil) ⇒ Space

Open a space file, optionally providing the page size to use. Pages that aren't 16 KiB may not be supported well.



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# File 'lib/innodb/space.rb', line 24

def initialize(file, page_size=nil)
  @file = File.open(file)
  @size = @file.stat.size

  if page_size
    @page_size = page_size
  else
    @page_size = fsp_flags[:page_size]
  end

  @pages = (@size / @page_size)
  @compressed = fsp_flags[:compressed]
  @record_describer = nil
end

Instance Attribute Details

#page_size ⇒ Object (readonly)

The size (in bytes) of each page in the space.



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# File 'lib/innodb/space.rb', line 44

def page_size
  @page_size
end

#pages ⇒ Object (readonly)

The number of pages in the space.



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# File 'lib/innodb/space.rb', line 50

def pages
  @pages
end

#record_describer ⇒ Object

An object which can be used to describe records found in pages within this space.



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# File 'lib/innodb/space.rb', line 41

def record_describer
  @record_describer
end

#size ⇒ Object (readonly)

The size (in bytes) of the space



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# File 'lib/innodb/space.rb', line 47

def size
  @size
end

Instance Method Details

#data_dictionary ⇒ Object

Get the Innodb::Page::SysDataDictionaryHeader page for a system space.



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# File 'lib/innodb/space.rb', line 188

def data_dictionary
  page(7) if system_space?
end

#each_index ⇒ Object

Iterate through each index by guessing that the root pages will be present starting at page 3, and walking forward until we find a non- root page. This should work fine for IBD files, but not for ibdata files.



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# File 'lib/innodb/space.rb', line 208

def each_index
  unless block_given?
    return enum_for(:each_index)
  end

  if system_space?
    data_dictionary.each_index do |table_name, index_name, index|
      yield index
    end
  else
    (3...@pages).each do |page_number|
      page = page(page_number)
      if page.type == :INDEX && page.root?
        yield index(page_number)
      else
        break
      end
    end
  end
end

#each_inode ⇒ Object

Iterate through Innodb::Inode objects in the space.



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# File 'lib/innodb/space.rb', line 246

def each_inode
  unless block_given?
    return enum_for(:each_inode)
  end

  each_inode_list.each do |name, list|
    list.each do |page|
      page.each_inode do |inode|
        yield inode
      end
    end
  end
end

#each_inode_list ⇒ Object

Iterate through Innodb::Inode lists in the space.



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# File 'lib/innodb/space.rb', line 235

def each_inode_list
  unless block_given?
    return enum_for(:each_inode_list)
  end

  inode_lists.each do |name|
    yield name, list(name)
  end
end

#each_page(start_page = 0) ⇒ Object

Iterate through all pages in a space, returning the page number and an Innodb::Page object for each one.



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# File 'lib/innodb/space.rb', line 262

def each_page(start_page=0)
  unless block_given?
    return enum_for(:each_page, start_page)
  end

  (start_page...@pages).each do |page_number|
    current_page = page(page_number)
    yield page_number, current_page if current_page
  end
end

#each_page_status(start_page = 0) ⇒ Object 



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# File 'lib/innodb/space.rb', line 318

def each_page_status(start_page=0)
  unless block_given?
    return enum_for(:each_page_with_status, start_page)
  end

  each_xdes do |xdes|
    xdes.each_page_status do |page_number, page_status|
      next if page_number < start_page
      next if page_number >= @pages

      if this_page = page(page_number)
        yield page_number, this_page, page_status
      end
    end
  end
end

#each_page_type_region(start_page = 0) {|region| ... } ⇒ Object

Iterate through unique regions in the space by page type. This is useful to achieve an overall view of the space.

Yields:

  • (region) 


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# File 'lib/innodb/space.rb', line 341

def each_page_type_region(start_page=0)
  unless block_given?
    return enum_for(:each_page_type_region, start_page)
  end

  region = nil
  each_page_status(start_page) do |page_number, page, page_status|
    page_type = type_for_page(page, page_status)
    if region && region[:type] == page_type
      region[:end] = page_number
      region[:count] += 1
    else
      yield region if region
      region = {
        :start => page_number,
        :end   => page_number,
        :type  => page_type,
        :count => 1,
      }
    end
  end
  yield region if region
end

#each_xdes ⇒ Object

Iterate through all extent descriptors for the space, returning an Innodb::Xdes object for each one.



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# File 'lib/innodb/space.rb', line 304

def each_xdes
  unless block_given?
    return enum_for(:each_xdes)
  end

  each_xdes_page do |xdes_page|
    xdes_page.each_xdes do |xdes|
      # Only return initialized XDES entries; :state will be nil for extents
      # that have not been allocated yet.
      yield xdes if xdes.xdes[:state]
    end
  end
end

#each_xdes_list ⇒ Object

Iterate through Innodb::Xdes lists in the space.



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# File 'lib/innodb/space.rb', line 279

def each_xdes_list
  unless block_given?
    return enum_for(:each_xdes_list)
  end

  xdes_lists.each do |name|
    yield name, list(name)
  end
end

#each_xdes_page ⇒ Object

Iterate through all FSP_HDR/XDES pages, returning an Innodb::Page object for each one.



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# File 'lib/innodb/space.rb', line 291

def each_xdes_page
  unless block_given?
    return enum_for(:each_xdes_page)
  end

  xdes_page_numbers.each do |page_number|
    current_page = page(page_number)
    yield current_page if current_page
  end
end

#extent_size ⇒ Object

The size (in bytes) of an extent.



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# File 'lib/innodb/space.rb', line 89

def extent_size
  1048576
end

#fsp ⇒ Object

Get (and cache) the FSP header from the FSP_HDR page.



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

def fsp
  @fsp ||= page(0).fsp_header
end

#fsp_flags ⇒ Object

The FSP header flags, decoded. If the page size has not been initialized, reach into the raw bytes of the FSP_HDR page and attempt to decode the flags field that way.



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# File 'lib/innodb/space.rb', line 80

def fsp_flags
  if @page_size
    return fsp[:flags]
  else
    raw_fsp_header_flags
  end
end

#index(root_page_number, record_describer = nil) ⇒ Object

Get an Innodb::Index object for a specific index by root page number.



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# File 'lib/innodb/space.rb', line 200

def index(root_page_number, record_describer=nil)
  Innodb::Index.new(self, root_page_number, record_describer || @record_describer)
end

#inode_lists ⇒ Object

An array of Innodb::Inode list names.



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# File 'lib/innodb/space.rb', line 230

def inode_lists
  [:full_inodes, :free_inodes]
end

#list(name) ⇒ Object

Get an Innodb::List object for a specific list by list name.



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# File 'lib/innodb/space.rb', line 193

def list(name)
  if xdes_lists.include?(name) || inode_lists.include?(name)
    fsp[name]
  end
end

#page(page_number) ⇒ Object

Get an Innodb::Page object for a specific page by page number.



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# File 'lib/innodb/space.rb', line 142

def page(page_number)
  this_page = Innodb::Page.parse(self, page_data(page_number))

  if this_page.type == :INDEX
    this_page.record_describer = @record_describer
  end

  this_page
end

#page_data(page_number) ⇒ Object

Get the raw byte buffer for a specific page by page number.



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# File 'lib/innodb/space.rb', line 134

def page_data(page_number)
  offset = page_number.to_i * page_size
  return nil unless offset < @size
  return nil unless (offset + page_size) <= @size
  read_at_offset(offset, page_size)
end

#pages_per_extent ⇒ Object

The number of pages per extent.



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# File 'lib/innodb/space.rb', line 94

def pages_per_extent
  extent_size / page_size
end

#pages_per_xdes_page ⇒ Object

The number of pages per FSP_HDR/XDES page. This is crudely mapped to the page size, and works for pages down to 1KiB.



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# File 'lib/innodb/space.rb', line 100

def pages_per_xdes_page
  page_size
end

#raw_fsp_header_flags ⇒ Object

Read the FSP header "flags" field by byte offset within the space file. This is useful in order to initialize the page size, as we can't properly read the FSP_HDR page before we know its size.



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# File 'lib/innodb/space.rb', line 55

def raw_fsp_header_flags
  # A simple sanity check. The FIL header should be initialized in page 0,
  # to offset 0 and page type :FSP_HDR (8).
  page_offset = BinData::Uint32be.read(read_at_offset(4, 4))
  page_type   = BinData::Uint16be.read(read_at_offset(24, 2))
  unless page_offset == 0 && Innodb::Page::PAGE_TYPE[page_type] == :FSP_HDR
    raise "Something is very wrong; Page 0 does not seem to be type FSP_HDR"
  end

  # Another sanity check. The Space ID should be the same in both the FIL
  # and FSP headers.
  fil_space = BinData::Uint32be.read(read_at_offset(34, 4))
  fsp_space = BinData::Uint32be.read(read_at_offset(38, 4))
  unless fil_space == fsp_space
    raise "Something is very wrong; FIL and FSP header Space IDs don't match"
  end

  # Well, we're as sure as we can be. Read the flags field and decode it.
  flags_value = BinData::Uint32be.read(read_at_offset(54, 4))
  Innodb::Page::FspHdrXdes.decode_flags(flags_value)
end

#read_at_offset(offset, size) ⇒ Object

Get the raw byte buffer of size bytes at offset in the file.



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# File 'lib/innodb/space.rb', line 128

def read_at_offset(offset, size)
  @file.seek(offset)
  @file.read(size)
end

#rseg_page?(page_number) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/innodb/space.rb', line 178

def rseg_page?(page_number)
  if trx_sys
    trx_sys.rsegs.include?({
      :space_id => 0,
      :page_number => page_number,
    })
  end
end

#system_space? ⇒ Boolean

Determine whether this space looks like a system space. If the initial pages in the space match the SYSTEM_SPACE_PAGE_MAP, it is likely to be a system space.

Returns:

  • (Boolean) 


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# File 'lib/innodb/space.rb', line 155

def system_space?
  SYSTEM_SPACE_PAGE_MAP.each do |page_number, type|
    # We can't use page() here, because system_space? need to be used
    # in the Innodb::Page::Sys.parse to determine what type of page
    # is being looked at. Using page() would cause us to keep recurse
    # infinitely. Use Innodb::Page.new instead to load the page as
    # simply as possible.
    test_page = Innodb::Page.new(self, page_data(page_number))
    return false unless test_page.type == type
  end
  true
end

#trx_sys ⇒ Object

Get the Innodb::Page::TrxSys page for a system space.



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# File 'lib/innodb/space.rb', line 174

def trx_sys
  page(5) if system_space?
end

#type_for_page(page, page_status) ⇒ Object 



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# File 'lib/innodb/space.rb', line 335

def type_for_page(page, page_status)
  page_status[:free] ? "FREE (#{page.type})" : page.type
end

#xdes_entry_for_page(page_number) ⇒ Object

The XDES entry offset for a given page within its FSP_HDR/XDES page's XDES array.



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# File 'lib/innodb/space.rb', line 116

def xdes_entry_for_page(page_number)
  relative_page_number = page_number - xdes_page_for_page(page_number)
  relative_page_number / pages_per_extent
end

#xdes_for_page(page_number) ⇒ Object

Return the Innodb::Xdes entry which represents a given page.



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# File 'lib/innodb/space.rb', line 122

def xdes_for_page(page_number)
  xdes_array = page(xdes_page_for_page(page_number)).each_xdes.to_a
  xdes_array[xdes_entry_for_page(page_number)]
end

#xdes_lists ⇒ Object

An array of Innodb::Xdes list names.



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# File 'lib/innodb/space.rb', line 274

def xdes_lists
  [:free, :free_frag, :full_frag]
end

#xdes_page_for_page(page_number) ⇒ Object

The FSP_HDR/XDES page which will contain the XDES entry for a given page.



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# File 'lib/innodb/space.rb', line 110

def xdes_page_for_page(page_number)
  page_number - (page_number % pages_per_xdes_page)
end

#xdes_page_numbers ⇒ Object

An array of all FSP/XDES page numbers for the space.



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# File 'lib/innodb/space.rb', line 105

def xdes_page_numbers
  (0..(@pages / pages_per_xdes_page)).map { |n| n * pages_per_xdes_page }
end