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) ⇒ 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 25

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

  @system_page_size = fsp_flags[:system_page_size]
  @page_size        = fsp_flags[:page_size]
  @compressed       = fsp_flags[:compressed]

  @pages = (@size / @page_size)
  @innodb_system = nil
  @record_describer = nil
end

Instance Attribute Details

#innodb_system ⇒ Object

The Innodb::System to which this space belongs, if any.



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# File 'lib/innodb/space.rb', line 39

def innodb_system
  @innodb_system
end

#page_size ⇒ Object (readonly)

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



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# File 'lib/innodb/space.rb', line 49

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 55

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 43

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 52

def size
  @size
end

#system_page_size ⇒ Object (readonly)

The system default page size (in bytes), equivalent to UNIV_PAGE_SIZE.



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

def system_page_size
  @system_page_size
end

Instance Method Details

#data_dictionary_page ⇒ Object

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



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

def data_dictionary_page
  page(page_sys_data_dictionary) if system_space?
end

#each_index ⇒ Object

Iterate through all indexes in the space.



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# File 'lib/innodb/space.rb', line 306

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

  each_index_root_page_number do |page_number|
    yield index(page_number)
  end

  nil
end

#each_index_root_page_number ⇒ Object

Iterate through all root page numbers for indexes in the space.



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# File 'lib/innodb/space.rb', line 280

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

  if innodb_system
    # Retrieve the index root page numbers from the data dictionary.
    innodb_system.data_dictionary.each_index_by_space_id(space_id) do |record|
      yield record["PAGE_NO"]
    end
  else
    # Guess that the index root pages will be present starting at page 3,
    # and walk forward until we find a non-root page. This should work fine
    # for IBD files, if they haven't added indexes online.
    (3...@pages).each do |page_number|
      page = page(page_number)
      if page.type == :INDEX && page.root?
        yield page_number
      end
    end
  end

  nil
end

#each_inode ⇒ Object

Iterate through Innodb::Inode objects in the space.



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

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_allocated_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 324

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 351

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

Iterate through all pages, yielding the page number, page object, and page status.



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# File 'lib/innodb/space.rb', line 420

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 444

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 404

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 368

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 391

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

  each_xdes_page_number do |page_number|
    current_page = page(page_number)
    yield current_page if current_page and [:FSP_HDR, :XDES].include?(current_page.type)
  end
end

#each_xdes_page_number ⇒ Object

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



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# File 'lib/innodb/space.rb', line 379

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

  0.step(pages - 1, pages_per_bookkeeping_page).each do |n|
    yield n
  end
end

#extent_size ⇒ Object

The size (in bytes) of an extent.



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# File 'lib/innodb/space.rb', line 154

def extent_size
  pages_per_extent * page_size
end

#fsp ⇒ Object

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



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# File 'lib/innodb/space.rb', line 228

def fsp
  @fsp ||= page(page_fsp_hdr).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 114

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

#ibuf_bitmap_page_for_page(page_number) ⇒ Object

The IBUF_BITMAP page which will contain the bitmap entry for a given page.



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# File 'lib/innodb/space.rb', line 170

def ibuf_bitmap_page_for_page(page_number)
  page_number - (page_number % pages_per_bookkeeping_page) + 1
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 274

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 319

def inode_lists
  [:full_inodes, :free_inodes]
end

#inspect ⇒ Object 



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# File 'lib/innodb/space.rb', line 71

def inspect
  "<%s file=%s, page_size=%i, pages=%i>" % [
    self.class.name,
    name.inspect,
    page_size,
    pages,
  ]
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 267

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

#name ⇒ Object

Return a string which can uniquely identify this space. Be careful not to do anything which could instantiate a BufferCursor so that we can use this method in cursor initialization.



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# File 'lib/innodb/space.rb', line 60

def name
  return @name if @name

  prefix = ""
  if File.extname(@file.path) == ".ibd"
    prefix = File.basename(File.dirname(@file.path)) + "/"
  end

  @name = prefix + File.basename(@file.path)
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 202

def page(page_number)
  Innodb::Page.parse(self, page_data(page_number))
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 194

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

#page_fsp_hdr ⇒ Object

Return the page number for the space’s FSP_HDR page.



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# File 'lib/innodb/space.rb', line 223

def page_fsp_hdr
  0
end

#page_sys_data_dictionary ⇒ Object

Return the page number for the space’s SYS data dictionary header.



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# File 'lib/innodb/space.rb', line 257

def page_sys_data_dictionary
  7
end

#page_trx_sys ⇒ Object

Return the page number for the space’s TRX_SYS page.



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# File 'lib/innodb/space.rb', line 237

def page_trx_sys
  5
end

#pages_per_bookkeeping_page ⇒ Object

The number of pages per FSP_HDR/XDES/IBUF_BITMAP 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 160

def pages_per_bookkeeping_page
  page_size
end

#pages_per_extent ⇒ Object

The number of pages per extent.



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# File 'lib/innodb/space.rb', line 123

def pages_per_extent
  # Note that uncompressed tables and compressed tables using the same page
  # size will have a different number of pages per "extent" because InnoDB
  # compression uses the FSP_EXTENT_SIZE define (which is then based on the
  # UNIV_PAGE_SIZE define, which may be based on the innodb_page_size system
  # variable) for compressed tables rather than something based on the actual
  # compressed page size.
  #
  # For this reason, an "extent" differs in size as follows (the maximum page
  # size supported for compressed tables is the innodb_page_size):
  #
  #   innodb_page_size                | innodb compression              |
  #   page size | extent size | pages | page size | extent size | pages |
  #   16384     | 1 MiB       | 64    | 16384     | 1 MiB       | 64    |
  #                                   | 8192      | 512 KiB     | 64    |
  #                                   | 4096      | 256 KiB     | 64    |
  #                                   | 2048      | 128 KiB     | 64    |
  #                                   | 1024      | 64 KiB      | 64    |
  #   8192      | 1 MiB       | 128   | 8192      | 1 MiB       | 128   |
  #                                   | 4096      | 512 KiB     | 128   |
  #                                   | 2048      | 256 KiB     | 128   |
  #                                   | 1024      | 128 KiB     | 128   |
  #   4096      | 1 MiB       | 256   | 4096      | 1 MiB       | 256   |
  #                                   | 2048      | 512 KiB     | 256   |
  #                                   | 1024      | 256 KiB     | 256   |
  #

  1048576 / system_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 83

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)).to_i
  page_type   = BinData::Uint16be.read(read_at_offset(24, 2)).to_i
  unless page_offset == 0 && Innodb::Page::PAGE_TYPE_BY_VALUE[page_type] == :FSP_HDR
    raise "Something is very wrong; Page 0 does not seem to be type FSP_HDR; got page type %i but expected %i" % [
      page_type,
      Innodb::Page::PAGE_TYPE[:FSP_HDR][:value],
    ]
  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)).to_i
  fsp_space = BinData::Uint32be.read(read_at_offset(38, 4)).to_i
  unless fil_space == fsp_space
    raise "Something is very wrong; FIL and FSP header Space IDs don't match: FIL is %i but FSP is %i" % [
      fil_space,
      fsp_space,
    ]
  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 188

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 246

def rseg_page?(page_number)
  if trx_sys
    rseg_match = trx_sys.rsegs.select { |rseg|
      rseg[:space_id] == 0 && rseg[:page_number] == page_number
    }

    ! rseg_match.empty?
  end
end

#space_id ⇒ Object 



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# File 'lib/innodb/space.rb', line 232

def space_id
  fsp[:space_id]
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 209

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 242

def trx_sys
  page(page_trx_sys) if system_space?
end

#type_for_page(page, page_status) ⇒ Object

A helper to produce a printable page type.



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# File 'lib/innodb/space.rb', line 438

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 176

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 182

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 363

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 165

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