Class: Innodb::Page::Inode

Inherits:
Innodb::Page show all
Defined in:
lib/innodb/page/inode.rb

Overview

A specialized class for handling INODE pages, which contain index FSEG (file segment) information. This allows all extents and individual pages assigned to each index to be found.

Constant Summary collapse

FRAG_ARRAY_N_SLOTS =

The number of “slots” (each representing one page) in the fragment array within each Inode entry.

32
FRAG_SLOT_SIZE =

The size (in bytes) of each slot in the fragment array.

4
MAGIC_N_VALUE =

A magic number which helps determine if an Inode structure is in use and populated with valid data.

97937874

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.



102
103
104
105
106
107
108
109
110
111
112
113
114
 
# File 'lib/innodb/page/inode.rb', line 102

def dump
  super

  puts "list entry:"
  pp list_entry
  puts

  puts "inodes:"
  each_inode do |i|
    pp i
  end
  puts
end

#each_inode ⇒ Object

Iterate through all Inodes in the inode array.



93
94
95
96
97
98
99
 
# File 'lib/innodb/page/inode.rb', line 93

def each_inode
  inode_cursor = cursor(pos_inode_array)
  inodes_per_page.times do
    this_inode = inode(inode_cursor)
    yield this_inode if this_inode[:fseg_id] != 0
  end
end

#inode(cursor) ⇒ Object

Read a single Inode entry from the provided cursor.



71
72
73
74
75
76
77
78
79
80
81
82
83
84
 
# File 'lib/innodb/page/inode.rb', line 71

def inode(cursor)
  {
    :fseg_id            => cursor.get_uint64,
    :not_full_n_used    => cursor.get_uint32,
    :free               => Innodb::List::Xdes.new(@space,
                            Innodb::List.get_base_node(cursor)),
    :not_full           => Innodb::List::Xdes.new(@space,
                            Innodb::List.get_base_node(cursor)),
    :full               => Innodb::List::Xdes.new(@space,
                            Innodb::List.get_base_node(cursor)),
    :magic_n            => cursor.get_uint32,
    :frag_array         => page_number_array(FRAG_ARRAY_N_SLOTS, cursor),
  }
end

#inode_at(offset) ⇒ Object

Read a single Inode entry from the provided byte offset by creating a cursor and reading the inode using the inode method.



88
89
90
 
# File 'lib/innodb/page/inode.rb', line 88

def inode_at(offset)
  inode(cursor(offset))
end

#inodes_per_page ⇒ Object

The number of Inode entries that fit on a page.



42
43
44
 
# File 'lib/innodb/page/inode.rb', line 42

def inodes_per_page
  (size - pos_inode_array - 10) / size_inode
end

#list_entry ⇒ Object

Return the list entry.



47
48
49
50
 
# File 'lib/innodb/page/inode.rb', line 47

def list_entry
  c = cursor(pos_list_entry)
  Innodb::List.get_node(c)
end

#next_address ⇒ Object

Return the “next” address pointer from the list entry. This is used by Innodb::List::Inode to iterate through Inode lists.



60
61
62
 
# File 'lib/innodb/page/inode.rb', line 60

def next_address
  list_entry[:next]
end

#page_number_array(size, cursor) ⇒ Object

Read an array of page numbers (32-bit integers, which may be nil) from the provided cursor.



66
67
68
 
# File 'lib/innodb/page/inode.rb', line 66

def page_number_array(size, cursor)
  size.times.map { |n| Innodb::Page.maybe_undefined(cursor.get_uint32) }
end

#pos_inode_array ⇒ Object

Return the byte offset of the Inode array in the page, which immediately follows the list entry.



31
32
33
 
# File 'lib/innodb/page/inode.rb', line 31

def pos_inode_array
  pos_list_entry + size_list_entry
end

#pos_list_entry ⇒ Object

Return the byte offset of the list node, which immediately follows the FIL header.



20
21
22
 
# File 'lib/innodb/page/inode.rb', line 20

def pos_list_entry
  pos_fil_header + size_fil_header
end

#prev_address ⇒ Object

Return the “previous” address pointer from the list entry. This is used by Innodb::List::Inode to iterate through Inode lists.



54
55
56
 
# File 'lib/innodb/page/inode.rb', line 54

def prev_address
  list_entry[:prev]
end

#size_inode ⇒ Object

The size (in bytes) of an Inode entry.



36
37
38
39
 
# File 'lib/innodb/page/inode.rb', line 36

def size_inode
  (16 + (3 * Innodb::List::BASE_NODE_SIZE) +
    (FRAG_ARRAY_N_SLOTS * FRAG_SLOT_SIZE))
end

#size_list_entry ⇒ Object

Return the byte offset of the list node.



25
26
27
 
# File 'lib/innodb/page/inode.rb', line 25

def size_list_entry
  Innodb::List::NODE_SIZE
end