Class: Fluent::PgLogicalInput

Inherits:
Input
  • Object
show all
Defined in:
lib/fluent/plugin/in_pg_logical.rb

Instance Method Summary collapse

Constructor Details

#initialize ⇒ PgLogicalInput

Returns a new instance of PgLogicalInput.



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 8

def initialize
  require 'pg'
  super
end

Instance Method Details

#configure(conf) ⇒ Object 



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 24

def configure(conf)
  super

  # 'slot_name' parameter is required.
  if (@slotname.nil?)
    raise Fluent::ConfigError, "pg-logical: missing 'slotname' parameter."
  end

  # If 'create_slot' parameter is specified, 'plugin' name is required.
  if (!@create_slot.nil? and @plugin.nil?)
    raise Fluent::ConfigError, "pg-logical: 'create_slot' parameter reuiqres to specify 'plugin' parameter."
  end

  log.info ":host=>#{host} :dbname=>#{dbname} :port=>#{port} :user=>#{user} :tag=>#{tag} :slotname=>#{slotname} :plugin=>#{plugin} :status_interval=>#{status_interval}"
end

#create_replication_slot ⇒ Object

Create a replication slot



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 295

def create_replication_slot
  begin
    strbuf = "CREATE_REPLICATION_SLOT %s LOGICAL %s" % [@slotname, @plugin]
    puts strbuf
    @conn.exec(strbuf)
  rescue PG::Error
    # If if_not_exists is set, ignore the error
    if (@if_not_exists)
      log.info "pg-logical: could not create replication slot %s" % @slotname
      return
    end

    log.error "pg-logical: could not create replication slot %s" % @slotname
  end
end

#extractRecord(record) ⇒ Object

Return extracted WAL data into a hash map



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 172

def extractRecord(record)
  r = record.unpack("a")
  wal = {}

  if (r[0] == 'w') # WAL data
    # -- WAL data format ------
    # 1. 'w'	: byte
    # 2. start_lsn	: uint64
    # 3. end_lsn	: uint64
    # 4. send_time	: uint64
    # 5. data
    # ------------------------
    r = record.unpack("aNNNNNNc*")

    start_lsn_h = r[1]
    start_lsn_l = r[2]
    end_lsn_h = r[3]
    end_lsn_l = r[4]
    send_time_h = r[5]
    send_time_l = r[6]
    data = r[7 .. r.size].pack("C*")

    start_lsn = (start_lsn_h << 32) + start_lsn_l
    end_lsn = (end_lsn_h << 32) + end_lsn_l
    send_time = (send_time_h << 32) + send_time_l

    wal[:type] = 'w'
    wal[:start_lsn] = start_lsn
    wal[:end_lsn] = end_lsn
    wal[:send_time] = send_time
    wal[:data] = data
  elsif (r[0] == 'k') # keepalive message
    # -- Keepalive format ------
    # 1. 'k'	: byte
    # 2. end_lsn	: uint64
    # 3. send_time	: uint64
    # 4. reply_required : byte
    # ------------------------
    r = record.unpack("aNNNNc")

    end_lsn_h = r[1]
    end_lsn_l = r[2]
    send_time_h = r[3]
    send_time_l = r[4]
    reply_required = r[5]

    end_lsn = (end_lsn_h << 32) + end_lsn_l
    send_time = (send_time_h << 32) + send_time_l

    wal[:type] = 'k'
    wal[:end_lsn] = end_lsn
    wal[:send_time] = send_time
    wal[:reply_required] = reply_required
  end

  # Update reveive lsn
  if (@recv_lsn.nil? or wal[:end_lsn] > @recv_lsn)
    @recv_lsn = wal[:end_lsn]
  end

  return wal
end

#get_connection ⇒ Object

Get a connection



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 78

def get_connection
  begin
    return PG::connect(
                       :host => @host,
                       :port => @port,
                       :user => @user,
                       :password => @password,
                       :dbname => @dbname,
                       :application_name => 'pg-logical',
                       :replication => "database"
                     )
  rescue Exception => e
    log.warn "pg-logical: #{e}"
    sleep 5
    retry
  end
end

#run ⇒ Object 



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 53

def run
  begin
    streamLogicalLog
  rescue StandardError => e
    log.error "pg_logical: failed to execute query."
    log.error "error: #{e.message}"
    log.error e.backtrace.join("\n")
  end
end

#sendFeedback(now, last_status, force) ⇒ Object

Return the last feedback time



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 236

def sendFeedback(now, last_status, force)

  # If the user doesn't want status to be reported the
  # upstream server, be sure to exit before doing anything
  # at all.
  if (!force and now - last_status < @status_interval)
    return last_status
  end

  # Report current status to upstream server
  if (!@recv_lsn.nil?)
    # -- Feedback format ------
    # 1. 'r'	: byte
    # 2. write_lsn	: uint64
    # 3. flush_lsn	: uint64
    # 3. apply_lsn	: uint64
    # 4. send_time	: uint64
    # 5. reply_required : byte
    # ------------------------
    feedback_msg = ['r']

    recv_lsn_h = @recv_lsn >> 32
    recv_lsn_l = @recv_lsn & 0xFFFFFFFF

    # write
    feedback_msg.push(recv_lsn_h)
    feedback_msg.push(recv_lsn_l)

    # flush
    feedback_msg.push(recv_lsn_h)
    feedback_msg.push(recv_lsn_l)

    # apply
    feedback_msg.push(0)
    feedback_msg.push(0)

    # send_time
    now_h = now.to_i >> 32
    now_l = now.to_i & 0xFFFFFFFF
    feedback_msg.push(now_h)
    feedback_msg.push(now_l)

    # Require reply
    feedback_msg.push(0)
    packed = feedback_msg.pack("aN8c")

    @conn.flush
    if (!@conn.put_copy_data(packed))
      raise "error"
    end

    # Update last_status as we've sent
    last_status = now
  end

  return last_status
end

#shutdown ⇒ Object 



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 44

def shutdown
  if (!@conn.nil?)
    @conn.put_copy_end()
    @conn.flush()
  end

  Thread.kill(@thread)
end

#start ⇒ Object 



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 40

def start
  @thread = Thread.new(&method(:run))
end

#start_streaming ⇒ Object

Start logical replication



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 64

def start_streaming
  # Identify system, and get start lsn
  res = @conn.exec("IDENTIFY_SYSTEM")
  systemid = res.getvalue(0, 0)
  tli = res.getvalue(0, 1)
  xlogpos = res.getvalue(0, 2)
  dbname = res.getvalue(0, 3)

  # Start logical replication
  strbuf = "START_REPLICATION SLOT %s LOGICAL %s" % [@slotname, xlogpos]
  @conn.exec(strbuf)
end

#streamLogicalLog ⇒ Object

Main routine of pg-logical plugin. Stream logical WAL.



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# File 'lib/fluent/plugin/in_pg_logical.rb', line 97

def streamLogicalLog
  begin
    @conn = get_connection()

    # Create replication slot if required
    create_replication_slot()

    # Start replication
    start_streaming()

    record = nil
    socket = @conn.socket_io
    time_to_abort = false
    last_status = Time.now
    loop do
      # Get current timestamp
      now = Time.now

      # Send feedback if necessary
      last_status = sendFeedback(now, last_status, false)

      # Get a decoded WAL decode
      record = @conn.get_copy_data(true)

      # In async mode, and no data available. We block on reading but
      # not more than the specified timeout, so that we can send a
      # response back to the client.# In asynchronou mode,
      if (record == false)
        # XXX: maybe better to use libev?
        r = select([socket], [], [], 10.0)

        if (r.nil?)
          # Got a timeout or signal. Continue the loop and either
          # deliver a status packet to the server or just go back into
          # blocking.
          next
        end

        # There is actual data on socket, consume it.
        @conn.consume_input()
        next
      end

      # record is nil means that copy is done.
      if (record.nil?)
        next
      end

      # Process a record, get extracted record
      wal = extractRecord(record)

      if (wal[:type] == 'w')	# WAL data
        #log.info "[GET w] start : #{wal[:start_lsn]}, end : #{wal[:end_lsn]}, time : #{wal[:send_time]}, data : #{wal[:data]}"
        last_status = sendFeedback(now, last_status, true)

        @router.emit(@tag, Fluent::Engine.now, wal[:data])

      elsif (wal[:type] == 'k') # Keepalive data
        #log.info "[GET k] end : #{wal[:end_lsn]}, time : #{wal[:send_time]}, reply_required : #{wal[:reply_required]}"

        if (wal[:reply_required] == 1)
          last_status = sendFeedback(now, last_status, true)
        end
      end
    end
  rescue Exception => e
    log.warn "pg-logical: #{e}"
    sleep 5
    retry
  ensure
    @conn.finish if !@conn.nil?
  end
end