lvm2/daemons/lvmdbusd/main.py

# Copyright (C) 2015-2016 Red Hat, Inc. All rights reserved.
#
# This copyrighted material is made available to anyone wishing to use,
# modify, copy, or redistribute it subject to the terms and conditions
# of the GNU General Public License v.2.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

from . import cfg
from . import objectmanager
from . import utils
from .cfg import BUS_NAME, BASE_INTERFACE, BASE_OBJ_PATH, MANAGER_OBJ_PATH
import threading
from . import cmdhandler
import time
import signal
import dbus
import dbus.mainloop.glib
from . import lvmdb
# noinspection PyUnresolvedReferences
from gi.repository import GLib
from .fetch import StateUpdate
from .manager import Manager
import traceback
import queue
from . import udevwatch
from .utils import log_debug, log_error
import argparse
import os
import sys
from .cmdhandler import LvmFlightRecorder, supports_vdo
from .request import RequestEntry


class Lvm(objectmanager.ObjectManager):
	def __init__(self, object_path):
		super(Lvm, self).__init__(object_path, BASE_INTERFACE)


def process_request():
	while cfg.run.value != 0:
		# noinspection PyBroadException
		try:
			req = cfg.worker_q.get(True, 5)
			log_debug(
				"Method start: %s with args %s (callback = %s)" %
				(str(req.method), str(req.arguments), str(req.cb)))
			req.run_cmd()
			log_debug("Method complete: %s" % str(req.method))
		except queue.Empty:
			pass
		except Exception:
			st = traceback.format_exc()
			utils.log_error("process_request exception: \n%s" % st)


def check_bb_size(value):
	v = int(value)
	if v < 0:
		raise argparse.ArgumentTypeError(
			"positive integers only ('%s' invalid)" % value)
	return v


def install_signal_handlers():
	# Because of the glib main loop stuff the python signal handler code is
	# apparently not usable and we need to use the glib calls instead
	signal_add = None

	if hasattr(GLib, 'unix_signal_add'):
		signal_add = GLib.unix_signal_add
	elif hasattr(GLib, 'unix_signal_add_full'):
		signal_add = GLib.unix_signal_add_full

	if signal_add:
		signal_add(GLib.PRIORITY_HIGH, signal.SIGHUP, utils.handler, signal.SIGHUP)
		signal_add(GLib.PRIORITY_HIGH, signal.SIGINT, utils.handler, signal.SIGINT)
		signal_add(GLib.PRIORITY_HIGH, signal.SIGUSR1, utils.handler, signal.SIGUSR1)
	else:
		log_error("GLib.unix_signal_[add|add_full] are NOT available!")


def main():
	start = time.time()
	# Add simple command line handling
	parser = argparse.ArgumentParser()
	parser.add_argument(
		"--udev", action='store_true',
		help="Use udev for updating state",
		default=False,
		dest='use_udev')
	parser.add_argument(
		"--debug", action='store_true',
		help="Dump debug messages", default=False,
		dest='debug')
	parser.add_argument(
		"--nojson", action='store_false',
		help="Do not use LVM JSON output (disables lvmshell)", default=True,
		dest='use_json')
	parser.add_argument(
		"--lvmshell", action='store_true',
		help="Use the lvm shell, not fork & exec lvm",
		default=False,
		dest='use_lvm_shell')
	parser.add_argument(
		"--blackboxsize",
		help="Size of the black box flight recorder, 0 to disable",
		default=10,
		type=check_bb_size,
		dest='bb_size')

	use_session = os.getenv('LVMDBUSD_USE_SESSION', False)

	# Ensure that we get consistent output for parsing stdout/stderr
	os.environ["LC_ALL"] = "C"

	cfg.args = parser.parse_args()
	cfg.create_request_entry = RequestEntry

	# We create a flight recorder in cmdhandler too, but we replace it here
	# as the user may be specifying a different size.  The default one in
	# cmdhandler is for when we are running other code with a different main.
	cfg.blackbox = LvmFlightRecorder(cfg.args.bb_size)

	if cfg.args.use_lvm_shell and not cfg.args.use_json:
		log_error("You cannot specify --lvmshell and --nojson")
		sys.exit(1)

	# We will dynamically add interfaces which support vdo if it
	# exists.
	cfg.vdo_support = supports_vdo()

	if cfg.vdo_support and not cfg.args.use_json:
		log_error("You cannot specify --nojson when lvm has VDO support")
		sys.exit(1)

	# List of threads that we start up
	thread_list = []

	install_signal_handlers()

	dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
	dbus.mainloop.glib.threads_init()

	cmdhandler.set_execution(cfg.args.use_lvm_shell)

	if use_session:
		cfg.bus = dbus.SessionBus()
	else:
		cfg.bus = dbus.SystemBus()
	# The base name variable needs to exist for things to work.
	# noinspection PyUnusedLocal
	base_name = dbus.service.BusName(BUS_NAME, cfg.bus)
	cfg.om = Lvm(BASE_OBJ_PATH)
	cfg.om.register_object(Manager(MANAGER_OBJ_PATH))

	cfg.db = lvmdb.DataStore(cfg.args.use_json, cfg.vdo_support)

	# Using a thread to process requests, we cannot hang the dbus library
	# thread that is handling the dbus interface
	thread_list.append(
		threading.Thread(target=process_request, name='process_request'))

	# Have a single thread handling updating lvm and the dbus model so we
	# don't have multiple threads doing this as the same time
	updater = StateUpdate()
	thread_list.append(updater.thread)

	cfg.load = updater.load

	cfg.loop = GLib.MainLoop()

	for thread in thread_list:
		thread.damon = True
		thread.start()

	# Add udev watching
	if cfg.args.use_udev:
		log_debug('Utilizing udev to trigger updates')

	# In all cases we are going to monitor for udev until we get an
	# ExternalEvent.  In the case where we get an external event and the user
	# didn't specify --udev we will stop monitoring udev
	udevwatch.add()

	end = time.time()
	log_debug(
		'Service ready! total time= %.4f, lvm time= %.4f count= %d' %
		(end - start, cmdhandler.total_time, cmdhandler.total_count),
		'bg_black', 'fg_light_green')

	try:
		if cfg.run.value != 0:
			cfg.loop.run()
			udevwatch.remove()

			for thread in thread_list:
				thread.join()
	except KeyboardInterrupt:
		# If we are unable to register signal handler, we will end up here when
		# the service gets a ^C or a kill -2 <parent pid>
		utils.handler(signal.SIGINT)
	return 0