sleep.py

import os
from gi.repository import GLib, Gio

# ---

def handle_lock():
  print("Lock")

def handle_unlock():
  print("Unlock")

def handle_sleep():
  print("Sleep")

def handle_resume():
  print("Resume")

# ---

class Manager(Gio.DBusProxy):
  def __init__(self):
    Gio.DBusProxy.__init__(self, g_bus_type=Gio.BusType.SYSTEM, g_name="org.freedesktop.login1",
        g_object_path="/org/freedesktop/login1", g_interface_name="org.freedesktop.login1.Manager")
    self.init(None)

class Session(Gio.DBusProxy):
  def __init__(self, session_id):
    session_path = Manager().GetSession("(s)", str(session_id))
    Gio.DBusProxy.__init__(self, g_bus_type=Gio.BusType.SYSTEM, g_name="org.freedesktop.login1",
        g_object_path=session_path, g_interface_name="org.freedesktop.login1.Session")
    self.init(None)

# ---

class SleepHandler(Manager):
  def __init__(self):
    Manager.__init__(self)
    self.inhibit()

  def inhibit(self):
    self.fd = self.Inhibit("(ssss)", "sleep", "sleep.py", "do something during suspend",
        "delay")

  def do_g_signal(self, sender, signal, params):
    if signal == "PrepareForSleep":
      p = params.unpack()
      if p[0]:
        # About to go to sleep
        handle_sleep()
        os.close(self.fd)
      else:
        # Woke up from sleep
        self.inhibit()
        handle_resume()
      return True
    Manager.do_g_signal(self, sender, signal, params)


class LockHandler(Session):
  def do_g_signal(self, sender, signal, params):
    if signal == "Lock":
      handle_lock()
      return True
    if signal == "Unlock":
      handle_unlock()
      return True
    Session.do_g_signal(self, sender, signal, params)

# ---

sleep = SleepHandler()
lock  = LockHandler(os.environ["XDG_SESSION_ID"])

GLib.MainLoop().run()