Class: MysqlReplicator::BinlogClient

Inherits:
Object
  • Object
show all
Defined in:
lib/mysql_replicator/binlog_client.rb

Overview

Binlog handler using MySQL Replication Protocol

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(connection, server_id = 1001) ⇒ BinlogClient

Returns a new instance of BinlogClient.



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# File 'lib/mysql_replicator/binlog_client.rb', line 18

def initialize(connection, server_id = 1001)
  @connection = connection
  @server_id = server_id
  @checksum_type = nil
end

Instance Attribute Details

#connection ⇒ Object (readonly)

@rbs! attr_reader connection: MysqlReplicator::Connection



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# File 'lib/mysql_replicator/binlog_client.rb', line 13

def connection
  @connection
end

Instance Method Details

#configure_binlog_checksum ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 129

def configure_binlog_checksum
  result = @connection.query('SHOW VARIABLES LIKE "binlog_checksum"')
  @checksum_type = result[:rows][0][:value]

  case @checksum_type
  when 'NONE'
    # No checksum
    MysqlReplicator::Logger.debug 'Set binlog checksum to NONE'
  when 'CRC32'
    @connection.query('SET @master_binlog_checksum = "CRC32"')
    MysqlReplicator::Logger.debug 'Set binlog checksum to CRC32'
  else
    raise MysqlReplicator::Error, "Unknown binlog checksum type: #{@checksum_type}"
  end
end

#handle_binlog_events ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 169

def handle_binlog_events
  event_parser = MysqlReplicator::Binlogs::EventParser.new

  loop do
    packet = @connection.read_packet
    payload = packet[:payload]

    first_byte = payload[0].unpack('C')[0]

    case first_byte
    when 0x00
      binlog_event = event_parser.execute(payload[1..], @connection, @checksum_type == 'CRC32')

      case binlog_event[:event_type]
      when :QUERY, :WRITE_ROWS, :UPDATE_ROWS, :DELETE_ROWS
        @event_listener&.call(binlog_event)
      end
      MysqlReplicator::Logger.debug "Binlog event: #{binlog_event}"
    when 0xFF
      MysqlReplicator::Logger.error \
        "Binlog event error: #{payload[1, 2].unpack('v')[0]} - #{payload[3..]}"
      break
    when 0xFE
      MysqlReplicator::Logger.error 'Received EOF packet - binlog stream ended'
      break
    else
      MysqlReplicator::Logger.error "Unexpected packet type: 0x#{first_byte.to_s(16)}"
      break
    end
  end
end

#master_status ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 63

def master_status
  result = @connection.query('SHOW MASTER STATUS')
  row = result[:rows][0]
  { file: row[:file].to_s, position: row[:position].to_i }
end

#on(&block) ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 26

def on(&block)
  @event_listener = block
end

#register_as_slave ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 70

def register_as_slave
  @connection.reset_sequence_id

  # Payload of COM_REGISTER_SLAVE packet
  payload = [0x15].pack('C')
  # Server ID (4 bytes)
  payload += [@server_id].pack('V')
  # Hostname (empty string but properly formatted)
  hostname = ''
  payload += [hostname.length].pack('C') + hostname
  # Username (empty string but properly formatted)
  username = ''
  payload += [username.length].pack('C') + username
  # Password (empty string but properly formatted)
  password = ''
  payload += [password.length].pack('C') + password
  # MySQL port
  payload += [@connection.port].pack('V')
  # Replication rank = 0 (unused)
  payload += [0].pack('V')
  # Master ID = 0 (unused)
  payload += [0].pack('V')

  @connection.send_packet(payload)

  response = @connection.read_packet
  if response[:payload][0].unpack('C')[0] != 0x00
    raise MysqlReplicator::Error,
      'Failed to register as slave ' \
      "error code = #{response[:payload][1, 2].unpack('v')[0]}, " \
      "error message = #{response[:payload][9..]}"
  end

  MysqlReplicator::Logger.info 'Successfully registered as slave'
end

#start_binlog_dump(binlog_file, binlog_position) ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 148

def start_binlog_dump(binlog_file, binlog_position)
  @connection.reset_sequence_id

  # Payload of COM_BINLOG_DUMP packet
  payload = [0x12].pack('C')
  # Binlog position (4 bytes)
  payload += [Integer(binlog_position)].pack('V')
  # Flags (2 bytes)
  payload += [0].pack('v')
  # Slave server ID (4 bytes)
  payload += [@server_id].pack('V')
  # Binlog filename
  payload += binlog_file

  @connection.send_packet(payload)

  MysqlReplicator::Logger.info \
    "Started binlog dump from #{binlog_file} at position #{binlog_position}"
end

#start_replication ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 31

def start_replication
  @connection.connect unless @connection.connected?

  binlog_info = master_status
  binlog_file = binlog_info[:file]
  binlog_position = binlog_info[:position]

  configure_binlog_checksum if @checksum_type.nil?
  register_as_slave
  start_binlog_dump(binlog_file, binlog_position)

  begin
    handle_binlog_events
  rescue Interrupt
    stop_replication
  rescue => e
    MysqlReplicator::Logger.error \
      "Unexpected error: #{e.message},\n" \
      "Backtrace: #{e.backtrace.first(5).join("\n")}"

    stop_replication
  end
end

#stop_replication ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 56

def stop_replication
  @connection.flush_socket_buffer
  unregister_as_slave
  @connection.close
end

#unregister_as_slave ⇒ Object 



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# File 'lib/mysql_replicator/binlog_client.rb', line 107

def unregister_as_slave
  @connection.reset_sequence_id

  # Payload of COM_UNREGISTER_SLAVE packet
  payload = [0x1B].pack('C')
  # Connection ID (4 bytes)
  payload += [@connection.connection_id].pack('V')

  @connection.send_packet(payload)

  response = @connection.read_packet
  if response[:payload][0].unpack('C')[0] != 0x00
    raise MysqlReplicator::Error,
      'Failed to unregister as slave ' \
      "error code = #{response[:payload][1, 2].unpack('v')[0]}, " \
      "error message = #{response[:payload][9..]}"
  end

  MysqlReplicator::Logger.info 'Successfully unregistered as slave'
end