Class: Innodb::Page::FspHdrXdes

Inherits:
Innodb::Page show all
Extended by:
ReadBitsAtOffset
Defined in:
lib/innodb/page/fsp_hdr_xdes.rb

Overview

A specialized class for FSP_HDR (filespace header) and XDES (extent descriptor) page types. Each tablespace always has an FSP_HDR page as its first page (page 0), and has repeating XDES pages every 16,384 pages after that (page 16384, 32768, …). The FSP_HDR and XDES page structure is completely identical, with the exception that the FSP header structure is zero-filled on XDES pages, but populated on FSP_HDR pages.

The basic structure of FSP_HDR and XDES pages is: FIL header, FSP header, an array of 256 XDES entries, empty (unused) space, and FIL trailer.

Constant Summary collapse

FLAGS_PAGE_SIZE_SHIFT =

A value added to the adjusted exponent stored in the page size field of the flags in the FSP header.

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Constants inherited from Innodb::Page

PAGE_TYPE, PAGE_TYPE_BY_VALUE, SPECIALIZED_CLASSES

Instance Attribute Summary

Attributes inherited from Innodb::Page

#space

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ReadBitsAtOffset

read_bits_at_offset

Methods inherited from Innodb::Page

#checksum, #checksum_crc32, #checksum_crc32?, #checksum_innodb, #checksum_innodb?, #checksum_invalid?, #checksum_trailer, #checksum_type, #checksum_valid?, #corrupt?, #cursor, #each_page_body_byte_as_uint8, #each_page_header_byte_as_uint8, #fil_header, #fil_trailer, handle, #in_doublewrite_buffer?, #initialize, #inspect, #lsn, #lsn_low32_header, #lsn_low32_trailer, maybe_undefined, #misplaced?, #misplaced_offset?, #misplaced_space?, #name, #next, #offset, parse, #pos_fil_header, #pos_fil_trailer, #pos_page_body, #pos_partial_page_header, #prev, #size, #size_fil_header, #size_fil_trailer, #size_page_body, #size_partial_page_header, #space_id, #torn?, #type

Constructor Details

This class inherits a constructor from Innodb::Page

Class Method Details

.decode_flags(flags) ⇒ Object

Decode the “flags” field in the FSP header, returning a hash of useful decodings of the flags (based on MySQl 5.6 definitions). The flags are:

Offset Size Description 0 1 Post-Antelope Flag. 1 4 Compressed Page Size (zip_size). This is stored as a

power of 2, minus 9. Since 0 is reserved to mean "not
compressed", the minimum value is 1, thus making the
smallest page size 1024 (2 ** (9 + 1)).

5 1 Atomic Blobs Flag. 6 4 System Page Size (innodb_page_size, UNIV_PAGE_SIZE).

The setting of the system page size when the tablespace
was created, stored in the same format as the compressed
page size above.

10 1 Data Directory Flag.



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 44

def self.decode_flags(flags)
  system_page_size =
    shift_page_size(read_bits_at_offset(flags, 4, 6)) ||
    Innodb::Space::DEFAULT_PAGE_SIZE
  compressed_page_size = shift_page_size(read_bits_at_offset(flags, 4, 1))

  {
    :system_page_size => system_page_size,
    :compressed => compressed_page_size ? false : true,
    :page_size => compressed_page_size || system_page_size,
    :post_antelope => read_bits_at_offset(flags, 1, 0) == 1,
    :atomic_blobs => read_bits_at_offset(flags, 1, 5) == 1,
    :data_directory => read_bits_at_offset(flags, 1, 10) == 1,
    :value => flags,
  }
end

.shift_page_size(page_size_shifted) ⇒ Object 



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 22

def self.shift_page_size(page_size_shifted)
  if page_size_shifted != 0
    (1 << (FLAGS_PAGE_SIZE_SHIFT + page_size_shifted))
  end
end

Instance Method Details

#dump ⇒ Object

Dump the contents of a page for debugging purposes.



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 181

def dump
  super

  puts "fsp header:"
  pp fsp_header
  puts

  puts "xdes entries:"
  each_xdes do |xdes|
    pp xdes
  end
  puts
end

#each_list ⇒ Object

Iterate through all lists in the file space.



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 125

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

  fsp_header.each do |key, value|
    yield key, value if value.is_a?(Innodb::List)
  end
end

#each_region {|{ :offset => pos_fsp_header, :length => size_fsp_header, :name => :fsp_header, :info => "FSP Header", }| ... } ⇒ Object

Yields:



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 151

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

  super do |region|
    yield region
  end

  yield({
    :offset => pos_fsp_header,
    :length => size_fsp_header,
    :name => :fsp_header,
    :info => "FSP Header",
  })

  each_xdes do |xdes|
    state = xdes.state || "unused"
    yield({
      :offset => xdes.offset,
      :length => size_xdes_entry,
      :name => "xdes_#{state}".to_sym,
      :info => "Extent Descriptor (#{state})",
    })
  end

  nil
end

#each_xdes ⇒ Object

Iterate through all XDES entries in order. This is useful for debugging, but each of these entries is actually a node in some other list. The state field in the XDES entry indicates which type of list it is present in, although not necessarily which list (e.g. :fseg).



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 139

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

  cursor(pos_xdes_array).name("xdes_array") do |c|
    entries_in_xdes_array.times do |n|
      yield Innodb::Xdes.new(self, c)
    end
  end
end

#entries_in_xdes_array ⇒ Object

The number of entries in the XDES array. Defined as page size divided by extent size.



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 79

def entries_in_xdes_array
  size / space.pages_per_extent
end

#fsp_header ⇒ Object

Read the FSP (filespace) header, which contains a few counters and flags, as well as list base nodes for each list maintained in the filespace.



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 93

def fsp_header
  @fsp_header ||= cursor(pos_fsp_header).name("fsp") do |c|
    {
      :space_id           => c.name("space_id") { c.get_uint32 },
      :unused             => c.name("unused") { c.get_uint32 },
      :size               => c.name("size") { c.get_uint32 },
      :free_limit         => c.name("free_limit") { c.get_uint32 },
      :flags              => c.name("flags") {
        self.class.decode_flags(c.get_uint32)
      },
      :frag_n_used        => c.name("frag_n_used") { c.get_uint32 },
      :free               => c.name("list[free]") {
        Innodb::List::Xdes.new(@space, Innodb::List.get_base_node(c))
      },
      :free_frag          => c.name("list[free_frag]") {
        Innodb::List::Xdes.new(@space, Innodb::List.get_base_node(c))
      },
      :full_frag          => c.name("list[full_frag]") {
        Innodb::List::Xdes.new(@space, Innodb::List.get_base_node(c))
      },
      :first_unused_seg   => c.name("first_unused_seg") { c.get_uint64 },
      :full_inodes        => c.name("list[full_inodes]") {
        Innodb::List::Inode.new(@space, Innodb::List.get_base_node(c))
      },
      :free_inodes        => c.name("list[free_inodes]") {
        Innodb::List::Inode.new(@space, Innodb::List.get_base_node(c))
      },
    }
  end
end

#pos_fsp_header ⇒ Object

The FSP header immediately follows the FIL header.



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 62

def pos_fsp_header
  pos_page_body
end

#pos_xdes_array ⇒ Object

The XDES entry array immediately follows the FSP header.



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 73

def pos_xdes_array
  pos_fsp_header + size_fsp_header
end

#size_fsp_header ⇒ Object

The FSP header contains six 32-bit integers, one 64-bit integer, and 5 list base nodes.



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 68

def size_fsp_header
  ((4 * 6) + (1 * 8) + (5 * Innodb::List::BASE_NODE_SIZE))
end

#size_xdes_array ⇒ Object 



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 87

def size_xdes_array
  entries_in_xdes_array * size_xdes_entry
end

#size_xdes_entry ⇒ Object 



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# File 'lib/innodb/page/fsp_hdr_xdes.rb', line 83

def size_xdes_entry
  @size_xdes_entry ||= Innodb::Xdes.new(self, cursor(pos_xdes_array)).size_entry
end