path: root/staslib/ctrl.py

# Copyright (c) 2022, Dell Inc. or its subsidiaries.  All rights reserved.
# SPDX-License-Identifier: Apache-2.0
# See the LICENSE file for details.
#
# This file is part of NVMe STorage Appliance Services (nvme-stas).
#
# Authors: Martin Belanger <Martin.Belanger@dell.com>
#
'''This module defines the base Controller object from which the
Dc (Discovery Controller) and Ioc (I/O Controller) objects are derived.'''

import time
import inspect
import logging
from gi.repository import GLib
from libnvme import nvme
from staslib import conf, defs, gutil, trid, udev, stas


DLP_CHANGED = (
    (nvme.NVME_LOG_LID_DISCOVER << 16) | (nvme.NVME_AER_NOTICE_DISC_CHANGED << 8) | nvme.NVME_AER_NOTICE
)  # 0x70f002


def get_eflags(dlpe):
    '''@brief Return eflags field of dlpe'''
    return int(dlpe.get('eflags', 0)) if dlpe else 0


def get_ncc(eflags: int):
    '''@brief Return True if Not Connected to CDC bit is asserted, False otherwise'''
    return eflags & nvme.NVMF_DISC_EFLAGS_NCC != 0


def dlp_supp_opts_as_string(dlp_supp_opts: int):
    '''@brief Return the list of options supported by the Get
    discovery log page command.
    '''
    data = {
        nvme.NVMF_LOG_DISC_LID_EXTDLPES: "EXTDLPES",
        nvme.NVMF_LOG_DISC_LID_PLEOS: "PLEOS",
        nvme.NVMF_LOG_DISC_LID_ALLSUBES: "ALLSUBES",
    }
    return [txt for msk, txt in data.items() if dlp_supp_opts & msk]


# ******************************************************************************
class Controller(stas.ControllerABC):  # pylint: disable=too-many-instance-attributes
    '''@brief Base class used to manage the connection to a controller.'''

    def __init__(self, tid: trid.TID, service, discovery_ctrl: bool = False):
        sysconf = conf.SysConf()
        self._nvme_options = conf.NvmeOptions()
        self._root = nvme.root()
        self._host = nvme.host(
            self._root, hostnqn=sysconf.hostnqn, hostid=sysconf.hostid, hostsymname=sysconf.hostsymname
        )
        self._host.dhchap_key = sysconf.hostkey if self._nvme_options.dhchap_hostkey_supp else None
        self._udev = udev.UDEV
        self._device = None  # Refers to the nvme device (e.g. /dev/nvme[n])
        self._ctrl = None  # libnvme's nvme.ctrl object
        self._connect_op = None

        super().__init__(tid, service, discovery_ctrl)

    def _release_resources(self):
        logging.debug('Controller._release_resources()    - %s | %s', self.id, self.device)

        if self._udev:
            self._udev.unregister_for_device_events(self._on_udev_notification)

        self._kill_ops()

        super()._release_resources()

        self._ctrl = None
        self._udev = None
        self._host = None
        self._root = None
        self._nvme_options = None

    @property
    def device(self) -> str:
        '''@brief return the Linux nvme device id (e.g. nvme3) or empty
        string if no device is associated with this controller'''
        if not self._device and self._ctrl and self._ctrl.name:
            self._device = self._ctrl.name

        return self._device or 'nvme?'

    def all_ops_completed(self) -> bool:
        '''@brief Returns True if all operations have completed. False otherwise.'''
        return self._connect_op is None or self._connect_op.completed()

    def connected(self):
        '''@brief Return whether a connection is established'''
        return self._ctrl and self._ctrl.connected()

    def controller_id_dict(self) -> dict:
        '''@brief return the controller ID as a dict.'''
        cid = super().controller_id_dict()
        cid['device'] = self.device
        return cid

    def details(self) -> dict:
        '''@brief return detailed debug info about this controller'''
        details = super().details()
        details.update(
            self._udev.get_attributes(self.device, ('hostid', 'hostnqn', 'model', 'serial', 'dctype', 'cntrltype'))
        )
        details['connected'] = str(self.connected())
        return details

    def info(self) -> dict:
        '''@brief Get the controller info for this object'''
        info = super().info()
        if self._connect_op:
            info['connect operation'] = str(self._connect_op.as_dict())
        return info

    def cancel(self):
        '''@brief Used to cancel pending operations.'''
        super().cancel()
        if self._connect_op:
            self._connect_op.cancel()

    def _kill_ops(self):
        if self._connect_op:
            self._connect_op.kill()
            self._connect_op = None

    def set_level_from_tron(self, tron):
        '''Set log level based on TRON'''
        if self._root:
            self._root.log_level("debug" if tron else "err")

    def _on_udev_notification(self, udev_obj):
        if not self._alive():
            logging.debug(
                'Controller._on_udev_notification() - %s | %s: Received event on dead object. udev_obj %s: %s',
                self.id,
                self.device,
                udev_obj.action,
                udev_obj.sys_name,
            )
            return

        if udev_obj.action == 'change':
            nvme_aen = udev_obj.get('NVME_AEN')
            nvme_event = udev_obj.get('NVME_EVENT')
            if isinstance(nvme_aen, str):
                logging.info('%s | %s - Received AEN: %s', self.id, udev_obj.sys_name, nvme_aen)
                self._on_aen(int(nvme_aen, 16))
            if isinstance(nvme_event, str):
                self._on_nvme_event(nvme_event)
        elif udev_obj.action == 'remove':
            logging.info('%s | %s - Received "remove" event', self.id, udev_obj.sys_name)
            self._on_ctrl_removed(udev_obj)
        else:
            logging.debug(
                'Controller._on_udev_notification() - %s | %s: Received "%s" event',
                self.id,
                udev_obj.sys_name,
                udev_obj.action,
            )

    def _on_ctrl_removed(self, udev_obj):  # pylint: disable=unused-argument
        if self._udev:
            self._udev.unregister_for_device_events(self._on_udev_notification)
        self._kill_ops()  # Kill all pending operations
        self._ctrl = None
        self._device = None
        self._connect_attempts = 0
        self._retry_connect_tmr.start()

    def _get_cfg(self):
        '''Get configuration parameters. These may either come from the [Global]
        section or from a "controller" entry in the configuration file. A
        definition found in a "controller" entry overrides the same definition
        found in the [Global] section.
        '''
        cfg = {}
        service_conf = conf.SvcConf()
        for option, keyword in (
            ('kato', 'keep_alive_tmo'),
            ('queue-size', 'queue_size'),
            ('hdr-digest', 'hdr_digest'),
            ('data-digest', 'data_digest'),
            ('nr-io-queues', 'nr_io_queues'),
            ('ctrl-loss-tmo', 'ctrl_loss_tmo'),
            ('disable-sqflow', 'disable_sqflow'),
            ('nr-poll-queues', 'nr_poll_queues'),
            ('nr-write-queues', 'nr_write_queues'),
            ('reconnect-delay', 'reconnect_delay'),
        ):
            # Check if the value is defined as a "controller" entry (i.e. override)
            ovrd_val = self.tid.cfg.get(option, None)
            if ovrd_val is not None:
                cfg[keyword] = ovrd_val
            else:
                # Check if the value is found in the [Global] section.
                glob_val = service_conf.get_option('Global', option)
                if glob_val is not None:
                    cfg[keyword] = glob_val

        return cfg

    def _do_connect(self):
        service_conf = conf.SvcConf()
        host_iface = (
            self.tid.host_iface
            if (self.tid.host_iface and not service_conf.ignore_iface and self._nvme_options.host_iface_supp)
            else None
        )
        self._ctrl = nvme.ctrl(
            self._root,
            subsysnqn=self.tid.subsysnqn,
            transport=self.tid.transport,
            traddr=self.tid.traddr,
            trsvcid=self.tid.trsvcid if self.tid.trsvcid else None,
            host_traddr=self.tid.host_traddr if self.tid.host_traddr else None,
            host_iface=host_iface,
        )
        self._ctrl.discovery_ctrl_set(self._discovery_ctrl)

        # Set the DHCHAP key on the controller
        # NOTE that this will eventually have to
        # change once we have support for AVE (TP8019)
        ctrl_dhchap_key = self.tid.cfg.get('dhchap-ctrl-secret')
        if ctrl_dhchap_key and self._nvme_options.dhchap_ctrlkey_supp:
            has_dhchap_key = hasattr(self._ctrl, 'dhchap_key')
            if not has_dhchap_key:
                logging.warning(
                    '%s | %s - libnvme-%s does not allow setting the controller DHCHAP key. Please upgrade libnvme.',
                    self.id,
                    self.device,
                    defs.LIBNVME_VERSION,
                )
            else:
                self._ctrl.dhchap_key = ctrl_dhchap_key

        # Audit existing nvme devices. If we find a match, then
        # we'll just borrow that device instead of creating a new one.
        udev_obj = self._find_existing_connection()
        if udev_obj is not None:
            # A device already exists.
            self._device = udev_obj.sys_name
            logging.debug(
                'Controller._do_connect()           - %s Found existing control device: %s', self.id, udev_obj.sys_name
            )
            self._connect_op = gutil.AsyncTask(
                self._on_connect_success, self._on_connect_fail, self._ctrl.init, self._host, int(udev_obj.sys_number)
            )
        else:
            cfg = self._get_cfg()
            logging.debug(
                'Controller._do_connect()           - %s Connecting to nvme control with cfg=%s', self.id, cfg
            )
            self._connect_op = gutil.AsyncTask(
                self._on_connect_success, self._on_connect_fail, self._ctrl.connect, self._host, cfg
            )

        self._connect_op.run_async()

    # --------------------------------------------------------------------------
    def _on_connect_success(self, op_obj: gutil.AsyncTask, data):
        '''@brief Function called when we successfully connect to the
        Controller.
        '''
        op_obj.kill()
        self._connect_op = None

        if not self._alive():
            logging.debug(
                'Controller._on_connect_success()   - %s | %s: Received event on dead object. data=%s',
                self.id,
                self.device,
                data,
            )
            return

        self._device = self._ctrl.name
        logging.info('%s | %s - Connection established!', self.id, self.device)
        self._connect_attempts = 0
        self._udev.register_for_device_events(self._device, self._on_udev_notification)

    def _on_connect_fail(self, op_obj: gutil.AsyncTask, err, fail_cnt):  # pylint: disable=unused-argument
        '''@brief Function called when we fail to connect to the Controller.'''
        op_obj.kill()
        self._connect_op = None

        if not self._alive():
            logging.debug(
                'Controller._on_connect_fail()      - %s Received event on dead object. %s %s',
                self.id,
                err.domain,
                err.message,
            )
            return

        if self._connect_attempts == 1:
            # Do a fast re-try on the first failure.
            self._retry_connect_tmr.set_timeout(self.FAST_CONNECT_RETRY_PERIOD_SEC)
        elif self._connect_attempts == 2:
            # If the fast connect re-try fails, then we can print a message to
            # indicate the failure, and start a slow re-try period.
            self._retry_connect_tmr.set_timeout(self.CONNECT_RETRY_PERIOD_SEC)
            logging.error('%s Failed to connect to controller. %s %s', self.id, err.domain, err.message)

        if self._should_try_to_reconnect():
            logging.debug(
                'Controller._on_connect_fail()      - %s %s. Retry in %s sec.',
                self.id,
                err,
                self._retry_connect_tmr.get_timeout(),
            )
            self._retry_connect_tmr.start()

    def disconnect(self, disconnected_cb, keep_connection):
        '''@brief Issue an asynchronous disconnect command to a Controller.
        Once the async command has completed, the callback 'disconnected_cb'
        will be invoked. If a controller is already disconnected, then the
        callback will be added to the main loop's next idle slot to be executed
        ASAP.

        @param disconnected_cb: Callback to be called when disconnect has
        completed. the callback must have this signature:
            def cback(controller: Controller, success: bool)
        @param keep_connection: Whether the underlying connection should remain
        in the kernel.
        '''
        logging.debug(
            'Controller.disconnect()            - %s | %s: keep_connection=%s', self.id, self.device, keep_connection
        )
        if self._ctrl and self._ctrl.connected() and not keep_connection:
            logging.info('%s | %s - Disconnect initiated', self.id, self.device)
            op = gutil.AsyncTask(self._on_disconn_success, self._on_disconn_fail, self._ctrl.disconnect)
            op.run_async(disconnected_cb)
        else:
            # Defer callback to the next main loop's idle period. The callback
            # cannot be called directly as the current Controller object is in the
            # process of being disconnected and the callback will in fact delete
            # the object. This would invariably lead to unpredictable outcome.
            GLib.idle_add(disconnected_cb, self, True)

    def _on_disconn_success(self, op_obj: gutil.AsyncTask, data, disconnected_cb):  # pylint: disable=unused-argument
        logging.debug('Controller._on_disconn_success()   - %s | %s', self.id, self.device)
        op_obj.kill()
        # Defer callback to the next main loop's idle period. The callback
        # cannot be called directly as the current Controller object is in the
        # process of being disconnected and the callback will in fact delete
        # the object. This would invariably lead to unpredictable outcome.
        GLib.idle_add(disconnected_cb, self, True)

    def _on_disconn_fail(
        self, op_obj: gutil.AsyncTask, err, fail_cnt, disconnected_cb
    ):  # pylint: disable=unused-argument
        logging.debug('Controller._on_disconn_fail()      - %s | %s: %s', self.id, self.device, err)
        op_obj.kill()
        # Defer callback to the next main loop's idle period. The callback
        # cannot be called directly as the current Controller object is in the
        # process of being disconnected and the callback will in fact delete
        # the object. This would invariably lead to unpredictable outcome.
        GLib.idle_add(disconnected_cb, self, False)


# ******************************************************************************
class Dc(Controller):
    '''@brief This object establishes a connection to one Discover Controller (DC).
    It retrieves the discovery log pages and caches them.
    It also monitors udev events associated with that DC and updates
    the cached discovery log pages accordingly.
    '''

    GET_LOG_PAGE_RETRY_RERIOD_SEC = 20
    REGISTRATION_RETRY_RERIOD_SEC = 5
    GET_SUPPORTED_RETRY_RERIOD_SEC = 5

    def __init__(self, staf, tid: trid.TID, log_pages=None, origin=None):
        super().__init__(tid, staf, discovery_ctrl=True)
        self._register_op = None
        self._get_supported_op = None
        self._get_log_op = None
        self._origin = origin
        self._log_pages = log_pages if log_pages else list()  # Log pages cache

        # For Avahi-discovered DCs that later become unresponsive, monitor how
        # long the controller remains unresponsive and if it does not return for
        # a configurable soak period (_ctrl_unresponsive_tmr), remove that
        # controller. Only Avahi-discovered controllers need this timeout-based
        # cleanup.
        self._ctrl_unresponsive_time = None  # The time at which connectivity was lost
        self._ctrl_unresponsive_tmr = gutil.GTimer(0, self._serv.controller_unresponsive, self.tid)

    def _release_resources(self):
        logging.debug('Dc._release_resources()            - %s | %s', self.id, self.device)
        super()._release_resources()

        if self._ctrl_unresponsive_tmr is not None:
            self._ctrl_unresponsive_tmr.kill()

        self._log_pages = list()
        self._ctrl_unresponsive_tmr = None

    def _kill_ops(self):
        super()._kill_ops()
        if self._get_log_op:
            self._get_log_op.kill()
            self._get_log_op = None
        if self._register_op:
            self._register_op.kill()
            self._register_op = None
        if self._get_supported_op:
            self._get_supported_op.kill()
            self._get_supported_op = None

    def all_ops_completed(self) -> bool:
        '''@brief Returns True if all operations have completed. False otherwise.'''
        return (
            super().all_ops_completed()
            and (self._get_log_op is None or self._get_log_op.completed())
            and (self._register_op is None or self._register_op.completed())
            and (self._get_supported_op is None or self._get_supported_op.completed())
        )

    @property
    def origin(self):
        '''@brief Return how this controller came into existence. Was it
        "discovered" through mDNS service discovery (TP8009), was it manually
        "configured" in stafd.conf, or was it a "referral".
        '''
        return self._origin

    @origin.setter
    def origin(self, value):
        '''@brief Set the origin of this controller.'''
        if value in ('discovered', 'configured', 'referral'):
            self._origin = value
            self._handle_lost_controller()
        else:
            logging.error('%s | %s - Trying to set invalid origin to %s', self.id, self.device, value)

    def reload_hdlr(self):
        '''@brief This is called when a "reload" signal is received.'''
        logging.debug('Dc.reload_hdlr()                   - %s | %s', self.id, self.device)

        self._handle_lost_controller()
        self._resync_with_controller()

    def info(self) -> dict:
        '''@brief Get the controller info for this object'''
        timeout = conf.SvcConf().zeroconf_persistence_sec
        unresponsive_time = (
            time.asctime(self._ctrl_unresponsive_time) if self._ctrl_unresponsive_time is not None else '---'
        )
        info = super().info()
        info['origin'] = self.origin
        if self.origin == 'discovered':
            # The code that handles "unresponsive" DCs only applies to
            # discovered DCs. So, let's only print that info when it's relevant.
            info['unresponsive timer'] = str(self._ctrl_unresponsive_tmr)
            info['unresponsive timeout'] = f'{timeout} sec' if timeout >= 0 else 'forever'
            info['unresponsive time'] = unresponsive_time
        if self._get_log_op:
            info['get log page operation'] = str(self._get_log_op.as_dict())
        if self._register_op:
            info['register operation'] = str(self._register_op.as_dict())
        if self._get_supported_op:
            info['get supported log page operation'] = str(self._get_supported_op.as_dict())
        return info

    def cancel(self):
        '''@brief Used to cancel pending operations.'''
        super().cancel()
        if self._get_log_op:
            self._get_log_op.cancel()
        if self._register_op:
            self._register_op.cancel()
        if self._get_supported_op:
            self._get_supported_op.cancel()

    def log_pages(self) -> list:
        '''@brief Get the cached log pages for this object'''
        return self._log_pages

    def referrals(self) -> list:
        '''@brief Return the list of referrals'''
        return [page for page in self._log_pages if page['subtype'] == 'referral']

    def _is_ddc(self):
        return self._ctrl and self._ctrl.dctype != 'cdc'

    def _on_aen(self, aen: int):
        if aen == DLP_CHANGED and self._get_log_op:
            self._get_log_op.run_async()

    def _handle_lost_controller(self):
        if self.origin == 'discovered':  # Only apply to mDNS-discovered DCs
            if not self._serv.is_avahi_reported(self.tid) and not self.connected():
                timeout = conf.SvcConf().zeroconf_persistence_sec
                if timeout >= 0:
                    if self._ctrl_unresponsive_time is None:
                        self._ctrl_unresponsive_time = time.localtime()
                        self._ctrl_unresponsive_tmr.start(timeout)
                        logging.info(
                            '%s | %s - Controller is not responding. Will be removed by %s unless restored',
                            self.id,
                            self.device,
                            time.ctime(time.mktime(self._ctrl_unresponsive_time) + timeout),
                        )

                    return

                logging.info('%s | %s - Controller not responding. Retrying...', self.id, self.device)

        self._ctrl_unresponsive_time = None
        self._ctrl_unresponsive_tmr.stop()
        self._ctrl_unresponsive_tmr.set_timeout(0)

    def is_unresponsive(self):
        '''@brief For "discovered" DC, return True if DC is unresponsive,
        False otherwise.
        '''
        return (
            self.origin == 'discovered'
            and not self._serv.is_avahi_reported(self.tid)
            and not self.connected()
            and self._ctrl_unresponsive_time is not None
            and self._ctrl_unresponsive_tmr.time_remaining() <= 0
        )

    def _resync_with_controller(self):
        '''Communicate with DC to resync the states'''
        if self._register_op:
            self._register_op.run_async()
        elif self._get_supported_op:
            self._get_supported_op.run_async()
        elif self._get_log_op:
            self._get_log_op.run_async()

    def _on_nvme_event(self, nvme_event: str):
        if nvme_event in ('connected', 'rediscover'):
            # This event indicates that the kernel
            # driver re-connected to the DC.
            logging.debug(
                'Dc._on_nvme_event()                - %s | %s: Received "%s" event',
                self.id,
                self.device,
                nvme_event,
            )
            self._resync_with_controller()

    def _find_existing_connection(self):
        return self._udev.find_nvme_dc_device(self.tid)

    def _post_registration_actions(self):
        # Need to check that supported_log_pages() is available (introduced in libnvme 1.2)
        get_slp = getattr(self._ctrl, 'supported_log_pages', None)
        if get_slp is None:
            logging.warning(
                '%s | %s - libnvme-%s does not support "Get supported log pages". Please upgrade libnvme.',
                self.id,
                self.device,
                defs.LIBNVME_VERSION,
            )

        if conf.SvcConf().pleo_enabled and self._is_ddc() and get_slp is not None:
            self._get_supported_op = gutil.AsyncTask(
                self._on_get_supported_success, self._on_get_supported_fail, get_slp
            )
            self._get_supported_op.run_async()
        else:
            self._get_log_op = gutil.AsyncTask(self._on_get_log_success, self._on_get_log_fail, self._ctrl.discover)
            self._get_log_op.run_async()

    # --------------------------------------------------------------------------
    def _on_connect_success(self, op_obj: gutil.AsyncTask, data):
        '''@brief Function called when we successfully connect to the
        Discovery Controller.
        '''
        super()._on_connect_success(op_obj, data)

        if not self._alive():
            return

        self._ctrl_unresponsive_time = None
        self._ctrl_unresponsive_tmr.stop()
        self._ctrl_unresponsive_tmr.set_timeout(0)

        if self._ctrl.is_registration_supported():
            self._register_op = gutil.AsyncTask(
                self._on_registration_success,
                self._on_registration_fail,
                self._ctrl.registration_ctlr,
                nvme.NVMF_DIM_TAS_REGISTER,
            )
            self._register_op.run_async()
        else:
            self._post_registration_actions()

    def _on_connect_fail(self, op_obj: gutil.AsyncTask, err, fail_cnt):
        '''@brief Function called when we fail to connect to the Controller.'''
        super()._on_connect_fail(op_obj, err, fail_cnt)

        if self._alive():
            self._handle_lost_controller()

    # --------------------------------------------------------------------------
    def _on_registration_success(self, op_obj: gutil.AsyncTask, data):  # pylint: disable=unused-argument
        '''@brief Function called when we successfully register with the
        Discovery Controller. See self._register_op object
        for details.

        NOTE: The name _on_registration_success() may be misleading. "success"
        refers to the fact that a successful exchange was made with the DC.
        It doesn't mean that the registration itself succeeded.
        '''
        if not self._alive():
            logging.debug(
                'Dc._on_registration_success()      - %s | %s: Received event on dead object.', self.id, self.device
            )
            return

        if data is not None:
            logging.warning('%s | %s - Registration error. %s.', self.id, self.device, data)
        else:
            logging.debug('Dc._on_registration_success()      - %s | %s', self.id, self.device)

        self._post_registration_actions()

    def _on_registration_fail(self, op_obj: gutil.AsyncTask, err, fail_cnt):
        '''@brief Function called when we fail to register with the
        Discovery Controller. See self._register_op object
        for details.
        '''
        if not self._alive():
            logging.debug(
                'Dc._on_registration_fail()         - %s | %s: Received event on dead object. %s',
                self.id,
                self.device,
                err,
            )
            op_obj.kill()
            return

        logging.debug(
            'Dc._on_registration_fail()         - %s | %s: %s. Retry in %s sec',
            self.id,
            self.device,
            err,
            Dc.REGISTRATION_RETRY_RERIOD_SEC,
        )
        if fail_cnt == 1:  # Throttle the logs. Only print the first time the command fails
            logging.error('%s | %s - Failed to register with Discovery Controller. %s', self.id, self.device, err)
        op_obj.retry(Dc.REGISTRATION_RETRY_RERIOD_SEC)

    # --------------------------------------------------------------------------
    def _on_get_supported_success(self, op_obj: gutil.AsyncTask, data):  # pylint: disable=unused-argument
        '''@brief Function called when we successfully retrieved the supported
        log pages from the Discovery Controller. See self._get_supported_op object
        for details.

        NOTE: The name _on_get_supported_success() may be misleading. "success"
        refers to the fact that a successful exchange was made with the DC.
        It doesn't mean that the Get Supported Log Page itself succeeded.
        '''
        if not self._alive():
            logging.debug(
                'Dc._on_get_supported_success()     - %s | %s: Received event on dead object.', self.id, self.device
            )
            return

        try:
            dlp_supp_opts = data[nvme.NVME_LOG_LID_DISCOVER] >> 16
        except (TypeError, IndexError):
            dlp_supp_opts = 0

        logging.debug(
            'Dc._on_get_supported_success()     - %s | %s: supported options = 0x%04X = %s',
            self.id,
            self.device,
            dlp_supp_opts,
            dlp_supp_opts_as_string(dlp_supp_opts),
        )

        if 'lsp' in inspect.signature(self._ctrl.discover).parameters:
            lsp = nvme.NVMF_LOG_DISC_LSP_PLEO if dlp_supp_opts & nvme.NVMF_LOG_DISC_LID_PLEOS else 0
            self._get_log_op = gutil.AsyncTask(
                self._on_get_log_success, self._on_get_log_fail, self._ctrl.discover, lsp
            )
        else:
            logging.warning(
                '%s | %s - libnvme-%s does not support setting PLEO bit. Please upgrade.',
                self.id,
                self.device,
                defs.LIBNVME_VERSION,
            )
            self._get_log_op = gutil.AsyncTask(self._on_get_log_success, self._on_get_log_fail, self._ctrl.discover)
        self._get_log_op.run_async()

    def _on_get_supported_fail(self, op_obj: gutil.AsyncTask, err, fail_cnt):
        '''@brief Function called when we fail to retrieve the supported log
        page from the Discovery Controller. See self._get_supported_op object
        for details.
        '''
        if not self._alive():
            logging.debug(
                'Dc._on_get_supported_fail()        - %s | %s: Received event on dead object. %s',
                self.id,
                self.device,
                err,
            )
            op_obj.kill()
            return

        logging.debug(
            'Dc._on_get_supported_fail()        - %s | %s: %s. Retry in %s sec',
            self.id,
            self.device,
            err,
            Dc.GET_SUPPORTED_RETRY_RERIOD_SEC,
        )
        if fail_cnt == 1:  # Throttle the logs. Only print the first time the command fails
            logging.error(
                '%s | %s - Failed to Get supported log pages from Discovery Controller. %s',
                self.id,
                self.device,
                err,
            )
        op_obj.retry(Dc.GET_SUPPORTED_RETRY_RERIOD_SEC)

    # --------------------------------------------------------------------------
    def _on_get_log_success(self, op_obj: gutil.AsyncTask, data):  # pylint: disable=unused-argument
        '''@brief Function called when we successfully retrieve the log pages
        from the Discovery Controller. See self._get_log_op object
        for details.
        '''
        if not self._alive():
            logging.debug(
                'Dc._on_get_log_success()           - %s | %s: Received event on dead object.', self.id, self.device
            )
            return

        # Note that for historical reasons too long to explain, the CDC may
        # return invalid addresses ('0.0.0.0', '::', or ''). Those need to
        # be filtered out.
        referrals_before = self.referrals()
        self._log_pages = (
            [
                {k.strip(): str(v).strip() for k, v in dictionary.items()}
                for dictionary in data
                if dictionary.get('traddr', '').strip() not in ('0.0.0.0', '::', '')
            ]
            if data
            else list()
        )
        logging.info(
            '%s | %s - Received discovery log pages (num records=%s).', self.id, self.device, len(self._log_pages)
        )
        referrals_after = self.referrals()
        self._serv.log_pages_changed(self, self.device)
        if referrals_after != referrals_before:
            logging.debug(
                'Dc._on_get_log_success()           - %s | %s: Referrals before = %s',
                self.id,
                self.device,
                referrals_before,
            )
            logging.debug(
                'Dc._on_get_log_success()           - %s | %s: Referrals after  = %s',
                self.id,
                self.device,
                referrals_after,
            )
            self._serv.referrals_changed()

    def _on_get_log_fail(self, op_obj: gutil.AsyncTask, err, fail_cnt):
        '''@brief Function called when we fail to retrieve the log pages
        from the Discovery Controller. See self._get_log_op object
        for details.
        '''
        if not self._alive():
            logging.debug(
                'Dc._on_get_log_fail()              - %s | %s: Received event on dead object. %s',
                self.id,
                self.device,
                err,
            )
            op_obj.kill()
            return

        logging.debug(
            'Dc._on_get_log_fail()              - %s | %s: %s. Retry in %s sec',
            self.id,
            self.device,
            err,
            Dc.GET_LOG_PAGE_RETRY_RERIOD_SEC,
        )
        if fail_cnt == 1:  # Throttle the logs. Only print the first time the command fails
            logging.error('%s | %s - Failed to retrieve log pages. %s', self.id, self.device, err)
        op_obj.retry(Dc.GET_LOG_PAGE_RETRY_RERIOD_SEC)


# ******************************************************************************
class Ioc(Controller):
    '''@brief This object establishes a connection to one I/O Controller.'''

    def __init__(self, stac, tid: trid.TID):
        self._dlpe = None
        super().__init__(tid, stac)

    def _find_existing_connection(self):
        return self._udev.find_nvme_ioc_device(self.tid)

    def _on_aen(self, aen: int):
        pass

    def _on_nvme_event(self, nvme_event):
        pass

    def reload_hdlr(self):
        '''@brief This is called when a "reload" signal is received.'''
        if not self.connected() and self._retry_connect_tmr.time_remaining() == 0:
            self._try_to_connect_deferred.schedule()

    @property
    def eflags(self):
        '''@brief Return the eflag field of the DLPE'''
        return get_eflags(self._dlpe)

    @property
    def ncc(self):
        '''@brief Return Not Connected to CDC status'''
        return get_ncc(self.eflags)

    def details(self) -> dict:
        '''@brief return detailed debug info about this controller'''
        details = super().details()
        details['dlpe'] = str(self._dlpe)
        details['dlpe.eflags.ncc'] = str(self.ncc)
        return details

    def update_dlpe(self, dlpe):
        '''@brief This method is called when a new DLPE associated
        with this controller is received.'''
        new_ncc = get_ncc(get_eflags(dlpe))
        old_ncc = self.ncc
        self._dlpe = dlpe

        if old_ncc and not new_ncc:  # NCC bit cleared?
            if not self.connected():
                self._connect_attempts = 0
                self._try_to_connect_deferred.schedule()

    def _should_try_to_reconnect(self):
        '''@brief This is used to determine when it's time to stop trying to connect'''
        max_connect_attempts = conf.SvcConf().connect_attempts_on_ncc if self.ncc else 0
        return max_connect_attempts == 0 or self._connect_attempts < max_connect_attempts