Class: MysqlBinlog::Binlog

Inherits:
Object
  • Object
show all
Defined in:
lib/mysql_binlog/binlog.rb

Overview

Read a binary log, parsing and returning events.

Examples

A basic example of using the Binlog class:

require 'mysql_binlog'
include MysqlBinlog

# Open a binary log from a file on disk.
binlog = Binlog.new(BinlogFileReader.new("mysql-bin.000001"))

# Iterate over all events from the log, printing the event type (such
# as :query_event, :write_rows_event, etc.)
binlog.each_event do |event|
  puts event[:type]
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(reader) ⇒ Binlog

Returns a new instance of Binlog.



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# File 'lib/mysql_binlog/binlog.rb', line 55

def initialize(reader)
  @reader = reader
  @field_parser = BinlogFieldParser.new(self)
  @event_parser = BinlogEventParser.new(self)
  @fde = nil
  @filter_event_types = nil
  @filter_flags = nil
  @ignore_rotate = false
  @max_query_length = 1048576
end

Instance Attribute Details

#event_parser ⇒ Object

Returns the value of attribute event_parser.



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# File 'lib/mysql_binlog/binlog.rb', line 49

def event_parser
  @event_parser
end

#fde ⇒ Object (readonly)

Returns the value of attribute fde.



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# File 'lib/mysql_binlog/binlog.rb', line 46

def fde
  @fde
end

#field_parser ⇒ Object

Returns the value of attribute field_parser.



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# File 'lib/mysql_binlog/binlog.rb', line 48

def field_parser
  @field_parser
end

#filter_event_types ⇒ Object

Returns the value of attribute filter_event_types.



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# File 'lib/mysql_binlog/binlog.rb', line 50

def filter_event_types
  @filter_event_types
end

#filter_flags ⇒ Object

Returns the value of attribute filter_flags.



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# File 'lib/mysql_binlog/binlog.rb', line 51

def filter_flags
  @filter_flags
end

#ignore_rotate ⇒ Object

Returns the value of attribute ignore_rotate.



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# File 'lib/mysql_binlog/binlog.rb', line 52

def ignore_rotate
  @ignore_rotate
end

#max_query_length ⇒ Object

Returns the value of attribute max_query_length.



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# File 'lib/mysql_binlog/binlog.rb', line 53

def max_query_length
  @max_query_length
end

#reader ⇒ Object

Returns the value of attribute reader.



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# File 'lib/mysql_binlog/binlog.rb', line 47

def reader
  @reader
end

Instance Method Details

#each_event ⇒ Object

Iterate through all events.



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# File 'lib/mysql_binlog/binlog.rb', line 185

def each_event
  unless block_given?
    return Enumerable::Enumerator.new(self, :each_event)
  end

  while event = read_event
    yield event
  end
end

#read_event ⇒ Object

Scan events until finding one that isn’t rejected by the filter rules. If there are no filter rules, this will return the next event provided by the reader.



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# File 'lib/mysql_binlog/binlog.rb', line 109

def read_event
  while true
    skip_this_event = false
    return nil if reader.end?

    filename = reader.filename
    position = reader.position

    # Read the common header for an event. Every event has a header.
    unless header = event_parser.event_header
      return nil
    end

    if @filter_event_types
      unless @filter_event_types.include? header[:event_type]
        skip_this_event = true
      end
    end
    
    if @filter_flags
      unless @filter_flags.include? header[:flags]
        skip_this_event = true
      end
    end

    # Never skip over rotate_event or format_description_event as they
    # are critical to understanding the format of this event stream.
    if skip_this_event
      unless [:rotate_event, :format_description_event].include? header[:event_type]
        skip_event(header)
        next
      end
    end

    fields = read_event_fields(header)

    case header[:event_type]
    when :rotate_event
      unless ignore_rotate
        reader.rotate(fields[:name], fields[:pos])
      end
    when :format_description_event
      process_fde(fields)
    end

    break
  end

  {
    :type     => header[:event_type],
    :filename => filename,
    :position => position,
    :header   => header,
    :event    => fields,
  }
end

#rewind ⇒ Object

Rewind to the beginning of the log, if supported by the reader. The reader may throw an exception if rewinding is not supported (e.g. for a stream-based reader).



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# File 'lib/mysql_binlog/binlog.rb', line 69

def rewind
  reader.rewind
end