useless_managed_object_client_ravelled

#!/usr/bin/python3
#+
# DBussy/Ravel example -- a client-side process for exercising the
# object-selection, property and managed-objects mechanisms. Run this
# after starting the accompanying useless_managed_object_server_xxx
# script and observe the messages that are printed.
#
# Copyright 2018 by Lawrence D'Oliveiro <ldo@geek-central.gen.nz>. This
# script is licensed CC0
# <https://creativecommons.org/publicdomain/zero/1.0/>; do with it
# what you will.
#-

import sys
import time
import signal
import asyncio
import dbussy as dbus
from dbussy import \
    DBUS
import ravel

useless_managed_objects_bus_name = "com.example.useless_managed_objects"
useless_managed_objects_iface_name = "com.example.useless_managed_objects"

start_time = time.time()
bus = ravel.session_bus()
bus.attach_asyncio()

signal.signal(signal.SIGINT, signal.SIG_DFL) # abort without raising KeyboardInterrupt on CTRL/C

def event_time() :
    "time relative to the start of the script run."
    return \
        time.time() - start_time
#end event_time

def log_msg(msg) :
    "prints a message line with a timestamp prefix."
    now = event_time()
    sys.stdout.write("%05.1f: %s\n" % (now, msg))
#end log_msg

async def sleep_till(when) :
    "delays a task until a specified time relative to the" \
    " start of the script run."
    delay = when - event_time()
    if delay >= 0 :
        await asyncio.sleep(delay)
    #end if
#end sleep_till

#+
# Interface
#-

@ravel.signal \
  (
    name = "prop_changed",
    path_keyword = "object_path",
    in_signature = "sa{sv}as",
    arg_keys = ("interface_name", "changed_properties", "invalidated_properties")
  )
def obj_prop_changed(object_path, interface_name, changed_properties, invalidated_properties) :
    "reports on changes to useless_managed_object properties."
    if interface_name == useless_managed_objects_iface_name :
        log_msg("prop changed on %s %s %s" % (object_path, repr(changed_properties), repr(invalidated_properties)))
    #end if
#end obj_prop_changed

@ravel.signal \
  (
    name = "object_added",
    in_signature = "oa{sa{sv}}",
    path_keyword = "object_path",
    args_keyword = "args",
  )
def objects_added(object_path, args) :
    log_msg("signal received: object “%s” added: %s" % (object_path, repr(args)))
#end objects_added

@ravel.signal \
  (
    name = "objects_removed",
    in_signature = "oas",
    path_keyword = "object_path",
    args_keyword = "args",
  )
def objects_removed(object_path, args) :
    log_msg("signal received: object “%s” removed: %s" % (object_path, repr(args)))
#end objects_removed

bus.listen_propchanged \
  (
    path = "/",
    fallback = True,
    interface = useless_managed_objects_iface_name,
    func = obj_prop_changed
  )
bus.listen_objects_added \
  (
    func = objects_added
  )
bus.listen_objects_removed \
  (
    func = objects_removed
  )
server = bus.loop.run_until_complete \
  (
    bus.get_proxy_interface_async
      (
        destination = useless_managed_objects_bus_name,
        path = "/",
        interface = useless_managed_objects_iface_name,
      )
  )
server = server(connection = bus.connection, dest = useless_managed_objects_bus_name)
  # only need one instance

#+
# Mainline
#-

async def create_object_if(path, initial) :
    "tries to create an object at the specified path, recovering gracefully" \
    " if it already exists."
    try :
        await server[path].create(initial)
    except dbus.DBusError as err :
        if err.name != DBUS.ERROR_OBJECT_PATH_IN_USE :
            raise
        #end if
        log_msg("object %s already exists" % path)
    #end try
#end create_object_if

async def report_time_props(path) :
    "reports the various time properties associated with an object."
    obj = server[path]
    log_msg \
      (
            "%s create = %05.1f, modify = %05.1f, access = %05.1f"
        %
            (
                path,
                (await obj.create_time) - start_time,
                (await obj.modify_time) - start_time,
                (await obj.access_time) - start_time,
            )
      )
#end report_time_props

async def actions() :
    log_msg("starting script")
    await sleep_till(3)
    await create_object_if("/path1", "val1")
    await sleep_till(4)
    server["/path1"].value = "val1a"
    await server.set_prop_flush()
    await sleep_till(6)
    await create_object_if("/path2", "val2")
    await report_time_props("/path1")
    log_msg \
      (
            "/path2 value = %s"
        %
            repr(await server["/path1"].value)
      )
    await report_time_props("/path2")
    await sleep_till(8)
    await server["/path1"].delete()
    await sleep_till(9)
    await create_object_if("/path3", "val3")
    server["/path2"].value = "val2a"
    await server.set_prop_flush()
    await sleep_till(11)
    await server["/path2"].delete()
    await sleep_till(14)
    await server["/path3"].delete()
    await sleep_till(18)
    log_msg("finishing script")
#end actions

bus.loop.run_until_complete(actions())