Class: MessageBus::Backends::Postgres::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/message_bus/backends/postgres.rb

Defined Under Namespace

Classes: Listener

Constant Summary collapse

INHERITED_CONNECTIONS = 
[]

Instance Method Summary collapse

Constructor Details

#initialize(config) ⇒ Client

Returns a new instance of Client.



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# File 'lib/message_bus/backends/postgres.rb', line 42

def initialize(config)
  @config = config
  @listening_on = {}
  @available = []
  @allocated = {}
  @subscribe_connection = nil
  @mutex = Mutex.new
  @pid = Process.pid
end

Instance Method Details

#add(channel, value) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 52

def add(channel, value)
  hold { |conn| exec_prepared(conn, 'insert_message', [channel, value]) { |r| r.getvalue(0, 0).to_i } }
end

#after_fork ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 89

def after_fork
  sync do
    @pid = Process.pid
    INHERITED_CONNECTIONS.concat(@available)
    @available.clear
    @listening_on.clear
  end
end

#backlog(channel, backlog_id) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 73

def backlog(channel, backlog_id)
  hold do |conn|
    exec_prepared(conn, 'channel_backlog', [channel, backlog_id]) { |r| r.values.each { |a| a[0] = a[0].to_i } }
  end || []
end

#clear_channel_backlog(channel, backlog_id, num_to_keep) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 63

def clear_channel_backlog(channel, backlog_id, num_to_keep)
  hold { |conn| exec_prepared(conn, 'clear_channel_backlog', [channel, backlog_id, num_to_keep]) }
  nil
end

#clear_global_backlog(backlog_id, num_to_keep) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 56

def clear_global_backlog(backlog_id, num_to_keep)
  if backlog_id > num_to_keep
    hold { |conn| exec_prepared(conn, 'clear_global_backlog', [backlog_id - num_to_keep]) }
    nil
  end
end

#destroy ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 106

def destroy
  sync do
    @available.each(&:close)
    @available.clear
  end
end

#expire(max_backlog_age) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 68

def expire(max_backlog_age)
  hold { |conn| exec_prepared(conn, 'expire', [max_backlog_age]) }
  nil
end

#expire_all_backlogs! ⇒ Object

use with extreme care, will nuke all of the data



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# File 'lib/message_bus/backends/postgres.rb', line 114

def expire_all_backlogs!
  reset!
end

#get_value(channel, id) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 85

def get_value(channel, id)
  hold { |conn| exec_prepared(conn, 'get_message', [channel, id]) { |r| r.getvalue(0, 0) } }
end

#global_backlog(backlog_id) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 79

def global_backlog(backlog_id)
  hold do |conn|
    exec_prepared(conn, 'global_backlog', [backlog_id]) { |r| r.values.each { |a| a[0] = a[0].to_i } }
  end || []
end

#max_id(channel = nil) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 118

def max_id(channel = nil)
  block = proc do |r|
    if r.ntuples > 0
      r.getvalue(0, 0).to_i
    else
      0
    end
  end

  if channel
    hold { |conn| exec_prepared(conn, 'max_channel_id', [channel], &block) }
  else
    hold { |conn| exec_prepared(conn, 'max_id', &block) }
  end
end

#publish(channel, data) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 134

def publish(channel, data)
  hold { |conn| exec_prepared(conn, 'publish', [channel, data]) }
end

#reset! ⇒ Object

Dangerous, drops the message_bus table containing the backlog if it exists.



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# File 'lib/message_bus/backends/postgres.rb', line 99

def reset!
  hold do |conn|
    conn.exec 'DROP TABLE IF EXISTS message_bus'
    create_table(conn)
  end
end

#subscribe(channel) ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 138

def subscribe(channel)
  obj = Object.new
  sync { @listening_on[channel] = obj }
  listener = Listener.new
  yield listener

  conn = @subscribe_connection = raw_pg_connection
  conn.exec "LISTEN #{channel}"
  listener.do_sub.call
  while listening_on?(channel, obj)
    conn.wait_for_notify(10) do |_, _, payload|
      break unless listening_on?(channel, obj)

      listener.do_message.call(nil, payload)
    end
  end
  listener.do_unsub.call

  conn.exec "UNLISTEN #{channel}"
  nil
ensure
  @subscribe_connection&.close
  @subscribe_connection = nil
end

#unsubscribe ⇒ Object 



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# File 'lib/message_bus/backends/postgres.rb', line 163

def unsubscribe
  sync { @listening_on.clear }
end