Class: Innodb::Page::TrxSys

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

Overview

A specialized class for TRX_SYS pages, which contain various information about the transaction system within InnoDB. Only one TRX_SYS page exists in any given InnoDB installation, and it is page 5 of the system tablespace (space 0), most commonly named “ibdata1”.

The basic structure of a TRX_SYS page is: FIL header, TRX_SYS header, empty space, master binary log information, empty space, local binary log information, empty space, doublewrite information (repeated twice), empty space, and FIL trailer.

Constant Summary collapse

MYSQL_LOG_MAGIC_N =

A magic number present in each MySQL binary log information structure, which helps identify whether the structure is populated or not.

873422344
N_RSEGS = 
128
DOUBLEWRITE_MAGIC_N =

A magic number present in each doublewrite buffer information structure, which helps identify whether the structure is populated or not.

536853855
DOUBLEWRITE_SPACE_ID_STORED_MAGIC_N =

A magic number present in the overall doublewrite buffer structure, which identifies whether the space id is stored.

1783657386

Constants inherited from Innodb::Page

PAGE_TYPE, PAGE_TYPE_BY_VALUE, SPECIALIZED_CLASSES

Instance Attribute Summary

Attributes inherited from Innodb::Page

#space

Instance Method Summary collapse

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

Instance Method Details

#binary_log ⇒ Object 



152
 
# File 'lib/innodb/page/trx_sys.rb', line 152

def binary_log;   trx_sys[:binary_log];   end

#doublewrite ⇒ Object 



154
 
# File 'lib/innodb/page/trx_sys.rb', line 154

def doublewrite;  trx_sys[:doublewrite];  end

#doublewrite_info(cursor) ⇒ Object

Read the overall doublewrite buffer structures



110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
 
# File 'lib/innodb/page/trx_sys.rb', line 110

def doublewrite_info(cursor)
  cursor.peek(pos_doublewrite_info) do |c_doublewrite|
    c_doublewrite.name("doublewrite") do |c|
      {
        :fseg => c.name("fseg") { Innodb::FsegEntry.get_inode(@space, c) },
        :page_info => [
          c.name("group[0]") { doublewrite_page_info(c) },
          c.name("group[1]") { doublewrite_page_info(c) },
        ],
        :space_id_stored =>
          (c.name("space_id_stored") { c.get_uint32 } ==
             DOUBLEWRITE_SPACE_ID_STORED_MAGIC_N),
      }
    end
  end
end

#doublewrite_page_info(cursor) ⇒ Object

Read a single doublewrite buffer information structure from a given cursor.



95
96
97
98
99
100
101
102
103
 
# File 'lib/innodb/page/trx_sys.rb', line 95

def doublewrite_page_info(cursor)
  {
    :magic_n => cursor.name("magic_n") { cursor.get_uint32 },
    :page_number => [
      cursor.name("page[0]") { cursor.get_uint32 },
      cursor.name("page[1]") { cursor.get_uint32 },
    ],
  }
end

#dump ⇒ Object

Dump the contents of a page for debugging purposes.



206
207
208
209
210
211
212
 
# File 'lib/innodb/page/trx_sys.rb', line 206

def dump
  super

  puts "trx_sys:"
  pp trx_sys
  puts
end

#each_region {|{ :offset => pos_trx_sys_header, :length => size_trx_sys_header, :name => :trx_sys_header, :info => "Transaction System Header", }| ... } ⇒ Object

Yields:



156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
 
# File 'lib/innodb/page/trx_sys.rb', line 156

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

  super do |region|
    yield region
  end

  yield({
    :offset => pos_trx_sys_header,
    :length => size_trx_sys_header,
    :name => :trx_sys_header,
    :info => "Transaction System Header",
  })

  rsegs.each do |rseg|
    yield({
      :offset => rseg[:offset],
      :length => 4 + 4,
      :name => :rseg,
      :info => "Rollback Segment",
    })
  end

  yield({
    :offset => pos_mysql_binary_log_info,
    :length => size_mysql_log_info,
    :name => :mysql_binary_log_info,
    :info => "Binary Log Info",
  })

  yield({
    :offset => pos_mysql_master_log_info,
    :length => size_mysql_log_info,
    :name => :mysql_master_log_info,
    :info => "Master Log Info",
  })

  yield({
    :offset => pos_doublewrite_info,
    :length => size_doublewrite_info,
    :name => :doublewrite_info,
    :info => "Double Write Buffer Info",
  })

  nil
end

#fseg ⇒ Object 



150
 
# File 'lib/innodb/page/trx_sys.rb', line 150

def fseg;         trx_sys[:fseg];         end

#master_log ⇒ Object 



153
 
# File 'lib/innodb/page/trx_sys.rb', line 153

def master_log;   trx_sys[:master_log];   end

#mysql_log_info(cursor, offset) ⇒ Object

Read a MySQL binary log information structure from a given position.



79
80
81
82
83
84
85
86
87
88
 
# File 'lib/innodb/page/trx_sys.rb', line 79

def mysql_log_info(cursor, offset)
  cursor.peek(offset) do |c|
    if c.name("magic_n") { c.get_uint32 } == MYSQL_LOG_MAGIC_N
      {
        :offset => c.name("offset") { c.get_uint64 },
        :name   => c.name("name")   { c.get_bytes(100) },
      }
    end
  end
end

#pos_doublewrite_info ⇒ Object

The doublewrite buffer information is located 200 bytes from the end of the page.



44
45
46
 
# File 'lib/innodb/page/trx_sys.rb', line 44

def pos_doublewrite_info
  size - 200
end

#pos_mysql_binary_log_info ⇒ Object

The local binary log information is located 1000 bytes from the end of the page.



38
39
40
 
# File 'lib/innodb/page/trx_sys.rb', line 38

def pos_mysql_binary_log_info
  size - 1000
end

#pos_mysql_master_log_info ⇒ Object

The master’s binary log information is located 2000 bytes from the end of the page.



32
33
34
 
# File 'lib/innodb/page/trx_sys.rb', line 32

def pos_mysql_master_log_info
  size - 2000
end

#pos_rsegs_array ⇒ Object 



22
23
24
 
# File 'lib/innodb/page/trx_sys.rb', line 22

def pos_rsegs_array
  pos_trx_sys_header + size_trx_sys_header
end

#pos_trx_sys_header ⇒ Object

The TRX_SYS header immediately follows the FIL header.



14
15
16
 
# File 'lib/innodb/page/trx_sys.rb', line 14

def pos_trx_sys_header
  pos_page_body
end

#rsegs ⇒ Object 



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

def rsegs;        trx_sys[:rsegs];        end

#rsegs_array(cursor) ⇒ Object 



58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
 
# File 'lib/innodb/page/trx_sys.rb', line 58

def rsegs_array(cursor)
  @rsegs_array ||= (0...N_RSEGS).to_a.inject([]) do |a, n|
    cursor.name("slot[#{n}]") do |c|
      slot = {
        :offset => c.position,
        :space_id => c.name("space_id") {
          Innodb::Page.maybe_undefined(c.get_uint32)
        },
        :page_number => c.name("page_number") {
          Innodb::Page.maybe_undefined(c.get_uint32)
        },
      }
      if slot[:space_id] && slot[:page_number]
        a << slot
      end
    end
    a
  end
end

#size_doublewrite_info ⇒ Object 



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

def size_doublewrite_info
  Innodb::FsegEntry::SIZE + (2 * (4 + 4 + 4)) + 4
end

#size_mysql_log_info ⇒ Object 



26
27
28
 
# File 'lib/innodb/page/trx_sys.rb', line 26

def size_mysql_log_info
  4 + 8 + 100
end

#size_trx_sys_header ⇒ Object 



18
19
20
 
# File 'lib/innodb/page/trx_sys.rb', line 18

def size_trx_sys_header
  8 + Innodb::FsegEntry::SIZE
end

#trx_id ⇒ Object 



149
 
# File 'lib/innodb/page/trx_sys.rb', line 149

def trx_id;       trx_sys[:trx_id];       end

#trx_sys ⇒ Object

Read the TRX_SYS headers and other information.



128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
 
# File 'lib/innodb/page/trx_sys.rb', line 128

def trx_sys
  @trx_sys ||= cursor(pos_trx_sys_header).name("trx_sys") do |c|
    {
      :trx_id       => c.name("trx_id") { c.get_uint64 },
      :fseg         => c.name("fseg") {
        Innodb::FsegEntry.get_inode(@space, c)
      },
      :rsegs        => c.name("rsegs") {
        rsegs_array(c)
      },
      :binary_log   => c.name("binary_log") {
        mysql_log_info(c, pos_mysql_binary_log_info)
      },
      :master_log   => c.name("master_log") {
        mysql_log_info(c, pos_mysql_master_log_info)
      },
      :doublewrite  => doublewrite_info(c),
    }
  end
end