Class: Innodb::Page::FspHdrXdes

Inherits:
Innodb::Page show all
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

Constants inherited from Innodb::Page

PAGE_TYPE, SPECIALIZED_CLASSES

Instance Attribute Summary

Attributes inherited from Innodb::Page

#space

Instance Method Summary collapse

Methods inherited from Innodb::Page

#cursor, #data, #fil_header, #initialize, #inspect, #lsn, maybe_undefined, #next, #offset, parse, #pos_fil_header, #pos_fil_trailer, #prev, #size, #size_fil_header, #size_fil_trailer, #type

Constructor Details

This class inherits a constructor from Innodb::Page

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 88

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 62

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_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 76

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

  c = cursor(pos_xdes_array)
  entries_in_xdes_array.times do
    yield Innodb::Xdes.new(self, c)
  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 32

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 38

def fsp_header
  c = cursor(pos_fsp_header)
  @fsp_header ||= {
    :space_id           => c.get_uint32,
    :unused             => c.get_uint32,
    :size               => c.get_uint32,
    :free_limit         => c.get_uint32,
    :flags              => c.get_uint32,
    :frag_n_used        => c.get_uint32,
    :free               => Innodb::List::Xdes.new(@space,
                            Innodb::List.get_base_node(c)),
    :free_frag          => Innodb::List::Xdes.new(@space,
                            Innodb::List.get_base_node(c)),
    :full_frag          => Innodb::List::Xdes.new(@space,
                            Innodb::List.get_base_node(c)),
    :first_unused_seg   => c.get_uint64,
    :full_inodes        => Innodb::List::Inode.new(@space,
                            Innodb::List.get_base_node(c)),
    :free_inodes        => Innodb::List::Inode.new(@space,
                            Innodb::List.get_base_node(c)),
  }
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 15

def pos_fsp_header
  pos_fil_header + size_fil_header
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 26

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 21

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