Module: PG::Replication

Defined in:
lib/pg/replication.rb,
lib/pg/replication/buffer.rb,
lib/pg/replication/version.rb,
lib/pg/replication/protocol.rb,
lib/pg/replication/pg_output.rb

Defined Under Namespace

Modules: PGOutput, Protocol Classes: Buffer

Constant Summary collapse

VERSION = 
"0.0.7"

Instance Method Summary collapse

Instance Method Details

#confirmed_slot_lsn(slot) ⇒ Object 



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# File 'lib/pg/replication.rb', line 118

def confirmed_slot_lsn(slot)
  lsn = query("    SELECT confirmed_flush_lsn FROM pg_replication_slots WHERE slot_name = '\#{slot}'\n  SQL\n  high, low = lsn.split(\"/\")\n  (high.to_i(16) << 32) + low.to_i(16)\nrescue StandardError\n  nil\nend\n").getvalue(0, 0)

#last_confirmed_lsn ⇒ Object 



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# File 'lib/pg/replication.rb', line 108

def last_confirmed_lsn
  @last_confirmed_lsn
end

#standby_status_update(write_lsn:, flush_lsn: write_lsn, apply_lsn: write_lsn, timestamp: Time.now, reply: false) ⇒ Object 



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# File 'lib/pg/replication.rb', line 87

def standby_status_update(
  write_lsn:,
  flush_lsn: write_lsn,
  apply_lsn: write_lsn,
  timestamp: Time.now,
  reply: false
)
  msg = [
    "r".bytes.first,
    write_lsn,
    flush_lsn,
    apply_lsn,
    (timestamp - Time.new(2_000, 1, 1, 0, 0, 0, 0)) * 10**6,
    reply ? 1 : 0,
  ].pack("CQ>Q>Q>Q>C")

  put_copy_data(msg)
  flush
  @last_confirmed_lsn = [@last_confirmed_lsn, write_lsn].compact.max
end

#start_pgoutput_replication_slot(slot, publication_names, **kwargs) ⇒ Object 



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# File 'lib/pg/replication.rb', line 72

def start_pgoutput_replication_slot(slot, publication_names, **kwargs)
  publication_names = publication_names.join(",")

  start_replication_slot(slot, **kwargs.merge(proto_version: "1", publication_names:))
    .map do |msg|
      case msg
      in Protocol::XLogData(data:, lsn:)
        data = data.force_encoding(internal_encoding)
        msg.with(data: PGOutput.read_message(Buffer.from_string(data)))
      else
        msg
      end
    end
end

#start_replication_slot(slot, logical: true, auto_keep_alive: true, location: "0/0", **params) ⇒ Object 



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# File 'lib/pg/replication.rb', line 11

def start_replication_slot(slot, logical: true, auto_keep_alive: true, location: "0/0", **params)
  keep_alive_secs = wal_receiver_status_interval
  @last_confirmed_lsn = confirmed_slot_lsn(slot) || 0

  start_query = "START_REPLICATION SLOT #{slot} #{logical ? "LOGICAL" : "PHYSICAL"} #{location}"
  unless params.empty?
    start_query << "("
    start_query << params
      .map { |k, v| "#{quote_ident(k.to_s)} '#{escape_string(v.to_s)}'" }
      .join(", ")
    start_query << ")"
  end
  query(start_query)

  last_keep_alive = Time.now

  Enumerator
    .new do |y|
      loop do
        if auto_keep_alive && Time.now - last_keep_alive > keep_alive_secs
          standby_status_update(write_lsn: @last_confirmed_lsn)
          last_keep_alive = Time.now
        end

        consume_input
        next if is_busy

        case get_copy_data(async: true)
        in nil
          get_last_result
          break

        in false
          IO.select([socket_io], nil, nil, keep_alive_secs)
          next

        in data
          case (msg = Protocol.read_message(Buffer.new(StringIO.new(data))))
          in Protocol::XLogData(lsn:, data:) if auto_keep_alive
            y << msg
            standby_status_update(write_lsn: lsn) if lsn > 0
            last_keep_alive = Time.now

          in Protocol::PrimaryKeepalive(current_lsn:, server_time:, asap: true) if auto_keep_alive
            standby_status_update(write_lsn: current_lsn)
            last_keep_alive = Time.now
            y << msg

          in Protocol::PrimaryKeepalive(current_lsn:)
            y << msg
            @last_confirmed_lsn = [@last_confirmed_lsn, current_lsn].compact.max

          else
            y << msg
          end
        end
      end
    end
    .lazy
end

#wal_receiver_status_interval ⇒ Object 



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# File 'lib/pg/replication.rb', line 112

def wal_receiver_status_interval
  query("    SELECT setting FROM pg_catalog.pg_settings WHERE name = 'wal_receiver_status_interval'\n  SQL\nend\n").getvalue(0, 0)&.to_i || 10