path: root/resources/libraries/python/TrafficGenerator.py

# Copyright (c) 2020 Cisco and/or its affiliates.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Performance testing traffic generator library."""

import time

from robot.api import logger
from robot.libraries.BuiltIn import BuiltIn

from .Constants import Constants
from .CpuUtils import CpuUtils
from .DropRateSearch import DropRateSearch
from .MLRsearch.AbstractMeasurer import AbstractMeasurer
from .MLRsearch.MultipleLossRatioSearch import MultipleLossRatioSearch
from .MLRsearch.ReceiveRateMeasurement import ReceiveRateMeasurement
from .PLRsearch.PLRsearch import PLRsearch
from .OptionString import OptionString
from .ssh import exec_cmd_no_error, exec_cmd
from .topology import NodeType
from .topology import NodeSubTypeTG
from .topology import Topology

__all__ = [u"TGDropRateSearchImpl", u"TrafficGenerator", u"OptimizedSearch"]


def check_subtype(node):
    """Return supported subtype of given node, or raise an exception.

    Currently only one subtype is supported,
    but we want our code to be ready for other ones.

    :param node: Topology node to check. Can be None.
    :type node: dict or NoneType
    :returns: Subtype detected.
    :rtype: NodeSubTypeTG
    :raises RuntimeError: If node is not supported, message explains how.
    """
    if node.get(u"type") is None:
        msg = u"Node type is not defined"
    elif node[u"type"] != NodeType.TG:
        msg = f"Node type is {node[u'type']!r}, not a TG"
    elif node.get(u"subtype") is None:
        msg = u"TG subtype is not defined"
    elif node[u"subtype"] != NodeSubTypeTG.TREX:
        msg = f"TG subtype {node[u'subtype']!r} is not supported"
    else:
        return NodeSubTypeTG.TREX
    raise RuntimeError(msg)


class TGDropRateSearchImpl(DropRateSearch):
    """Drop Rate Search implementation."""

    # def __init__(self):
    #     super(TGDropRateSearchImpl, self).__init__()

    def measure_loss(
            self, rate, frame_size, loss_acceptance, loss_acceptance_type,
            traffic_profile):
        """Runs the traffic and evaluate the measured results.

        :param rate: Offered traffic load.
        :param frame_size: Size of frame.
        :param loss_acceptance: Permitted drop ratio or frames count.
        :param loss_acceptance_type: Type of permitted loss.
        :param traffic_profile: Module name as a traffic profile identifier.
            See GPL/traffic_profiles/trex for implemented modules.
        :type rate: float
        :type frame_size: str
        :type loss_acceptance: float
        :type loss_acceptance_type: LossAcceptanceType
        :type traffic_profile: str
        :returns: Drop threshold exceeded? (True/False)
        :rtype: bool
        :raises NotImplementedError: If TG is not supported.
        :raises RuntimeError: If TG is not specified.
        """
        # we need instance of TrafficGenerator instantiated by Robot Framework
        # to be able to use trex_stl-*()
        tg_instance = BuiltIn().get_library_instance(
            u"resources.libraries.python.TrafficGenerator"
        )
        subtype = check_subtype(tg_instance.node)
        if subtype == NodeSubTypeTG.TREX:
            unit_rate = str(rate) + self.get_rate_type_str()
            tg_instance.trex_stl_start_remote_exec(
                self.get_duration(), unit_rate, frame_size, traffic_profile
            )
            loss = tg_instance.get_loss()
            sent = tg_instance.get_sent()
            if self.loss_acceptance_type_is_percentage():
                loss = (float(loss) / float(sent)) * 100
            logger.trace(
                f"comparing: {loss} < {loss_acceptance} {loss_acceptance_type}"
            )
            return float(loss) <= float(loss_acceptance)
        return False

    def get_latency(self):
        """Returns min/avg/max latency.

        :returns: Latency stats.
        :rtype: list
        """
        tg_instance = BuiltIn().get_library_instance(
            u"resources.libraries.python.TrafficGenerator"
        )
        return tg_instance.get_latency_int()


class TrexMode:
    """Defines mode of T-Rex traffic generator."""
    # Advanced stateful mode
    ASTF = u"ASTF"
    # Stateless mode
    STL = u"STL"


# TODO: Pylint says too-many-instance-attributes.
class TrafficGenerator(AbstractMeasurer):
    """Traffic Generator."""

    # TODO: Remove "trex" from lines which could work with other TGs.

    # Use one instance of TrafficGenerator for all tests in test suite
    ROBOT_LIBRARY_SCOPE = u"TEST SUITE"

    def __init__(self):
        # TODO: Separate into few dataclasses/dicts.
        #       Pylint dislikes large unstructured state, and it is right.
        self._node = None
        self._mode = None
        # TG interface order mapping
        self._ifaces_reordered = False
        # Result holding fields, to be removed.
        self._result = None
        self._loss = None
        self._sent = None
        self._latency = None
        self._received = None
        self._approximated_rate = None
        self._approximated_duration = None
        self._l7_data = None
        # Measurement input fields, needed for async stop result.
        self._start_time = None
        self._stop_time = None
        self._rate = None
        self._target_duration = None
        self._duration = None
        # Other input parameters, not knowable from measure() signature.
        self.frame_size = None
        self.traffic_profile = None
        self.traffic_directions = None
        self.negative_loss = None
        self.use_latency = None
        self.ppta = None
        self.resetter = None
        self.transaction_scale = None
        self.transaction_duration = None
        self.sleep_till_duration = None
        self.transaction_type = None
        self.duration_limit = None
        # Transient data needed for async measurements.
        self._xstats = (None, None)
        # TODO: Rename "xstats" to something opaque, so T-Rex is not privileged?

    @property
    def node(self):
        """Getter.

        :returns: Traffic generator node.
        :rtype: dict
        """
        return self._node

    def get_loss(self):
        """Return number of lost packets.

        :returns: Number of lost packets.
        :rtype: str
        """
        return self._loss

    def get_sent(self):
        """Return number of sent packets.

        :returns: Number of sent packets.
        :rtype: str
        """
        return self._sent

    def get_received(self):
        """Return number of received packets.

        :returns: Number of received packets.
        :rtype: str
        """
        return self._received

    def get_latency_int(self):
        """Return rounded min/avg/max latency.

        :returns: Latency stats.
        :rtype: list
        """
        return self._latency

    def get_approximated_rate(self):
        """Return approximated rate computed as ratio of transmitted packets
        over duration of trial.

        :returns: Approximated rate.
        :rtype: str
        """
        return self._approximated_rate

    def get_l7_data(self):
        """Return L7 data.

        :returns: Number of received packets.
        :rtype: dict
        """
        return self._l7_data

    def check_mode(self, expected_mode):
        """Check TG mode.

        :param expected_mode: Expected traffic generator mode.
        :type expected_mode: object
        :raises RuntimeError: In case of unexpected TG mode.
        """
        if self._mode == expected_mode:
            return
        raise RuntimeError(
            f"{self._node[u'subtype']} not running in {expected_mode} mode!"
        )

    # TODO: pylint says disable=too-many-locals.
    def initialize_traffic_generator(
            self, tg_node, tg_if1, tg_if2, tg_if1_adj_node, tg_if1_adj_if,
            tg_if2_adj_node, tg_if2_adj_if, osi_layer, tg_if1_dst_mac=None,
            tg_if2_dst_mac=None):
        """TG initialization.

        TODO: Document why do we need (and how do we use) _ifaces_reordered.

        :param tg_node: Traffic generator node.
        :param tg_if1: TG - name of first interface.
        :param tg_if2: TG - name of second interface.
        :param tg_if1_adj_node: TG if1 adjecent node.
        :param tg_if1_adj_if: TG if1 adjecent interface.
        :param tg_if2_adj_node: TG if2 adjecent node.
        :param tg_if2_adj_if: TG if2 adjecent interface.
        :param osi_layer: 'L2', 'L3' or 'L7' - OSI Layer testing type.
        :param tg_if1_dst_mac: Interface 1 destination MAC address.
        :param tg_if2_dst_mac: Interface 2 destination MAC address.
        :type tg_node: dict
        :type tg_if1: str
        :type tg_if2: str
        :type tg_if1_adj_node: dict
        :type tg_if1_adj_if: str
        :type tg_if2_adj_node: dict
        :type tg_if2_adj_if: str
        :type osi_layer: str
        :type tg_if1_dst_mac: str
        :type tg_if2_dst_mac: str
        :returns: nothing
        :raises RuntimeError: In case of issue during initialization.
        """
        subtype = check_subtype(tg_node)
        if subtype == NodeSubTypeTG.TREX:
            self._node = tg_node
            self._mode = TrexMode.ASTF if osi_layer == u"L7" else TrexMode.STL
            if1 = dict()
            if2 = dict()
            if1[u"pci"] = Topology().get_interface_pci_addr(self._node, tg_if1)
            if2[u"pci"] = Topology().get_interface_pci_addr(self._node, tg_if2)
            if1[u"addr"] = Topology().get_interface_mac(self._node, tg_if1)
            if2[u"addr"] = Topology().get_interface_mac(self._node, tg_if2)

            if osi_layer == u"L2":
                if1[u"adj_addr"] = if2[u"addr"]
                if2[u"adj_addr"] = if1[u"addr"]
            elif osi_layer in (u"L3", u"L7"):
                if1[u"adj_addr"] = Topology().get_interface_mac(
                    tg_if1_adj_node, tg_if1_adj_if
                )
                if2[u"adj_addr"] = Topology().get_interface_mac(
                    tg_if2_adj_node, tg_if2_adj_if
                )
            else:
                raise ValueError(u"Unknown OSI layer!")

            # in case of switched environment we can override MAC addresses
            if tg_if1_dst_mac is not None and tg_if2_dst_mac is not None:
                if1[u"adj_addr"] = tg_if1_dst_mac
                if2[u"adj_addr"] = tg_if2_dst_mac

            if min(if1[u"pci"], if2[u"pci"]) != if1[u"pci"]:
                if1, if2 = if2, if1
                self._ifaces_reordered = True

            master_thread_id, latency_thread_id, socket, threads = \
                CpuUtils.get_affinity_trex(
                    self._node, tg_if1, tg_if2,
                    tg_dtc=Constants.TREX_CORE_COUNT)

            if osi_layer in (u"L2", u"L3", u"L7"):
                exec_cmd_no_error(
                    self._node,
                    f"sh -c 'cat << EOF > /etc/trex_cfg.yaml\n"
                    f"- version: 2\n"
                    f"  c: {len(threads)}\n"
                    f"  limit_memory: {Constants.TREX_LIMIT_MEMORY}\n"
                    f"  interfaces: [\"{if1[u'pci']}\",\"{if2[u'pci']}\"]\n"
                    f"  port_info:\n"
                    f"      - dest_mac: \'{if1[u'adj_addr']}\'\n"
                    f"        src_mac: \'{if1[u'addr']}\'\n"
                    f"      - dest_mac: \'{if2[u'adj_addr']}\'\n"
                    f"        src_mac: \'{if2[u'addr']}\'\n"
                    f"  platform :\n"
                    f"      master_thread_id: {master_thread_id}\n"
                    f"      latency_thread_id: {latency_thread_id}\n"
                    f"      dual_if:\n"
                    f"          - socket: {socket}\n"
                    f"            threads: {threads}\n"
                    f"EOF'",
                    sudo=True, message=u"T-Rex config generation!"
                )
            else:
                raise ValueError(u"Unknown OSI layer!")

            TrafficGenerator.startup_trex(
                self._node, osi_layer, subtype=subtype
            )

    @staticmethod
    def startup_trex(tg_node, osi_layer, subtype=None):
        """Startup sequence for the TRex traffic generator.

        :param tg_node: Traffic generator node.
        :param osi_layer: 'L2', 'L3' or 'L7' - OSI Layer testing type.
        :param subtype: Traffic generator sub-type.
        :type tg_node: dict
        :type osi_layer: str
        :type subtype: NodeSubTypeTG
        :raises RuntimeError: If T-Rex startup failed.
        :raises ValueError: If OSI layer is not supported.
        """
        if not subtype:
            subtype = check_subtype(tg_node)
        if subtype == NodeSubTypeTG.TREX:
            for _ in range(0, 3):
                # Kill TRex only if it is already running.
                cmd = u"sh -c \"pgrep t-rex && pkill t-rex && sleep 3 || true\""
                exec_cmd_no_error(
                    tg_node, cmd, sudo=True, message=u"Kill TRex failed!"
                )

                # Configure TRex.
                ports = ''
                for port in tg_node[u"interfaces"].values():
                    if u'Mellanox' not in port.get(u'model'):
                        ports += f" {port.get(u'pci_address')}"

                cmd = f"sh -c \"cd {Constants.TREX_INSTALL_DIR}/scripts/ && " \
                    f"./dpdk_nic_bind.py -u {ports} || true\""
                exec_cmd_no_error(
                    tg_node, cmd, sudo=True,
                    message=u"Unbind PCI ports from driver failed!"
                )

                # Start TRex.
                cd_cmd = f"cd '{Constants.TREX_INSTALL_DIR}/scripts/'"
                trex_cmd = OptionString([u"nohup", u"./t-rex-64"])
                trex_cmd.add(u"-i")
                trex_cmd.add(u"--prefix $(hostname)")
                trex_cmd.add(u"--hdrh")
                trex_cmd.add(u"--no-scapy-server")
                trex_cmd.add_if(u"--astf", osi_layer == u"L7")
                # OptionString does not create double space if extra is empty.
                trex_cmd.add(f"{Constants.TREX_EXTRA_CMDLINE}")
                inner_command = f"{cd_cmd} && {trex_cmd} > /tmp/trex.log 2>&1 &"
                cmd = f"sh -c \"{inner_command}\" > /dev/null"
                try:
                    exec_cmd_no_error(tg_node, cmd, sudo=True)
                except RuntimeError:
                    cmd = u"sh -c \"cat /tmp/trex.log\""
                    exec_cmd_no_error(
                        tg_node, cmd, sudo=True,
                        message=u"Get TRex logs failed!"
                    )
                    raise RuntimeError(u"Start TRex failed!")

                # Test T-Rex API responsiveness.
                cmd = u"python3"
                cmd += f" {Constants.REMOTE_FW_DIR}/GPL/tools/trex/"
                if osi_layer in (u"L2", u"L3"):
                    cmd += f"trex_stl_assert.py"
                elif osi_layer == u"L7":
                    cmd += f"trex_astf_assert.py"
                else:
                    raise ValueError(u"Unknown OSI layer!")
                try:
                    exec_cmd_no_error(
                        tg_node, cmd, sudo=True,
                        message=u"T-Rex API is not responding!", retries=20
                    )
                except RuntimeError:
                    continue
                return
            # After max retries TRex is still not responding to API critical
            # error occurred.
            exec_cmd(tg_node, u"cat /tmp/trex.log", sudo=True)
            raise RuntimeError(u"Start T-Rex failed after multiple retries!")

    @staticmethod
    def is_trex_running(node):
        """Check if T-Rex is running using pidof.

        :param node: Traffic generator node.
        :type node: dict
        :returns: True if T-Rex is running otherwise False.
        :rtype: bool
        """
        ret, _, _ = exec_cmd(node, u"pgrep t-rex", sudo=True)
        return bool(int(ret) == 0)

    @staticmethod
    def teardown_traffic_generator(node):
        """TG teardown.

        :param node: Traffic generator node.
        :type node: dict
        :returns: nothing
        :raises RuntimeError: If node type is not a TG,
            or if T-Rex teardown fails.
        """
        subtype = check_subtype(node)
        if subtype == NodeSubTypeTG.TREX:
            exec_cmd_no_error(
                node,
                u"sh -c "
                u"\"if pgrep t-rex; then sudo pkill t-rex && sleep 3; fi\"",
                sudo=False,
                message=u"T-Rex kill failed!"
            )

    def trex_astf_stop_remote_exec(self, node):
        """Execute T-Rex ASTF script on remote node over ssh to stop running
        traffic.

        Internal state is updated with measurement results.

        :param node: T-Rex generator node.
        :type node: dict
        :raises RuntimeError: If stop traffic script fails.
        """
        command_line = OptionString().add(u"python3")
        dirname = f"{Constants.REMOTE_FW_DIR}/GPL/tools/trex"
        command_line.add(f"'{dirname}/trex_astf_stop.py'")
        command_line.change_prefix(u"--")
        for index, value in enumerate(self._xstats):
            if value is not None:
                value = value.replace(u"'", u"\"")
                command_line.add_equals(f"xstat{index}", f"'{value}'")
        stdout, _ = exec_cmd_no_error(
            node, command_line,
            message=u"T-Rex ASTF runtime error!"
        )
        self._parse_traffic_results(stdout)

    def trex_stl_stop_remote_exec(self, node):
        """Execute T-Rex STL script on remote node over ssh to stop running
        traffic.

        Internal state is updated with measurement results.

        :param node: T-Rex generator node.
        :type node: dict
        :raises RuntimeError: If stop traffic script fails.
        """
        command_line = OptionString().add(u"python3")
        dirname = f"{Constants.REMOTE_FW_DIR}/GPL/tools/trex"
        command_line.add(f"'{dirname}/trex_stl_stop.py'")
        command_line.change_prefix(u"--")
        for index, value in enumerate(self._xstats):
            if value is not None:
                value = value.replace(u"'", u"\"")
                command_line.add_equals(f"xstat{index}", f"'{value}'")
        stdout, _ = exec_cmd_no_error(
            node, command_line,
            message=u"T-Rex STL runtime error!"
        )
        self._parse_traffic_results(stdout)

    def stop_traffic_on_tg(self):
        """Stop all traffic on TG.

        :returns: Structure containing the result of the measurement.
        :rtype: ReceiveRateMeasurement
        :raises ValueError: If TG traffic profile is not supported.
        """
        subtype = check_subtype(self._node)
        if subtype != NodeSubTypeTG.TREX:
            raise ValueError(f"Unsupported TG subtype: {subtype!r}")
        if u"trex-astf" in self.traffic_profile:
            self.trex_astf_stop_remote_exec(self._node)
        elif u"trex-stl" in self.traffic_profile:
            self.trex_stl_stop_remote_exec(self._node)
        else:
            raise ValueError(u"Unsupported T-Rex traffic profile!")
        self._stop_time = time.monotonic()

        return self.get_measurement_result()

    def trex_astf_start_remote_exec(
            self, duration, multiplier, async_call=False):
        """Execute T-Rex ASTF script on remote node over ssh to start running
        traffic.

        In sync mode, measurement results are stored internally.
        In async mode, initial data including xstats are stored internally.

        This method contains the logic to compute duration as maximum time
        if transaction_scale is nonzero.
        The transaction_scale argument defines (limits) how many transactions
        will be started in total. As that amount of transaction can take
        considerable time (sometimes due to explicit delays in the profile),
        the real time a trial needs to finish is computed here. For now,
        in that case the duration argument is ignored, assuming it comes
        from ASTF-unaware search algorithm. The overall time a single
        transaction needs is given in parameter transaction_duration,
        it includes both explicit delays and implicit time it takes
        to transfer data (or whatever the transaction does).

        Currently it is observed TRex does not start the ASTF traffic
        immediately, an ad-hoc constant is added to the computed duration
        to compensate for that.

        If transaction_scale is zero, duration is not recomputed.
        It is assumed the subsequent result parsing gets the real duration
        if the traffic stops sooner for any reason.

        Currently, it is assumed traffic profile defines a single transaction.
        To avoid heavy logic here, the input rate is expected to be in
        transactions per second, as that directly translates to TRex multiplier,
        (assuming the profile does not override the default cps value of one).

        :param duration: Time expressed in seconds for how long to send traffic.
        :param multiplier: Traffic rate in transactions per second.
        :param async_call: If enabled then don't wait for all incoming traffic.
        :type duration: float
        :type multiplier: int
        :type async_call: bool
        :raises RuntimeError: In case of T-Rex driver issue.
        """
        self.check_mode(TrexMode.ASTF)
        p_0, p_1 = (1, 0) if self._ifaces_reordered else (0, 1)
        if not isinstance(duration, (float, int)):
            duration = float(duration)

        # Duration logic.
        computed_duration = duration
        if duration > 0.0:
            if self.transaction_scale:
                computed_duration = self.transaction_scale / multiplier
                # Log the computed duration,
                # so we can compare with what telemetry suggests
                # the real duration was.
                logger.debug(f"Expected duration {computed_duration}")
                computed_duration += 0.1115
        # Else keep -1.
        if self.duration_limit:
            computed_duration = min(computed_duration, self.duration_limit)

        command_line = OptionString().add(u"python3")
        dirname = f"{Constants.REMOTE_FW_DIR}/GPL/tools/trex"
        command_line.add(f"'{dirname}/trex_astf_profile.py'")
        command_line.change_prefix(u"--")
        dirname = f"{Constants.REMOTE_FW_DIR}/GPL/traffic_profiles/trex"
        command_line.add_with_value(
            u"profile", f"'{dirname}/{self.traffic_profile}.py'"
        )
        command_line.add_with_value(u"duration", f"{computed_duration!r}")
        command_line.add_with_value(u"frame_size", self.frame_size)
        command_line.add_with_value(u"multiplier", multiplier)
        command_line.add_with_value(u"port_0", p_0)
        command_line.add_with_value(u"port_1", p_1)
        command_line.add_with_value(
            u"traffic_directions", self.traffic_directions
        )
        command_line.add_if(u"async_start", async_call)
        command_line.add_if(u"latency", self.use_latency)
        command_line.add_if(u"force", Constants.TREX_SEND_FORCE)

        self._start_time = time.monotonic()
        self._rate = multiplier
        stdout, _ = exec_cmd_no_error(
            self._node, command_line, timeout=computed_duration + 10.0,
            message=u"T-Rex ASTF runtime error!"
        )

        if async_call:
            # no result
            self._target_duration = None
            self._duration = None
            self._received = None
            self._sent = None
            self._loss = None
            self._latency = None
            xstats = [None, None]
            self._l7_data = dict()
            self._l7_data[u"client"] = dict()
            self._l7_data[u"client"][u"active_flows"] = None
            self._l7_data[u"client"][u"established_flows"] = None
            self._l7_data[u"client"][u"traffic_duration"] = None
            self._l7_data[u"server"] = dict()
            self._l7_data[u"server"][u"active_flows"] = None
            self._l7_data[u"server"][u"established_flows"] = None
            self._l7_data[u"server"][u"traffic_duration"] = None
            if u"udp" in self.traffic_profile:
                self._l7_data[u"client"][u"udp"] = dict()
                self._l7_data[u"client"][u"udp"][u"connects"] = None
                self._l7_data[u"client"][u"udp"][u"closed_flows"] = None
                self._l7_data[u"client"][u"udp"][u"err_cwf"] = None
                self._l7_data[u"server"][u"udp"] = dict()
                self._l7_data[u"server"][u"udp"][u"accepted_flows"] = None
                self._l7_data[u"server"][u"udp"][u"closed_flows"] = None
            elif u"tcp" in self.traffic_profile:
                self._l7_data[u"client"][u"tcp"] = dict()
                self._l7_data[u"client"][u"tcp"][u"initiated_flows"] = None
                self._l7_data[u"client"][u"tcp"][u"connects"] = None
                self._l7_data[u"client"][u"tcp"][u"closed_flows"] = None
                self._l7_data[u"client"][u"tcp"][u"connattempt"] = None
                self._l7_data[u"server"][u"tcp"] = dict()
                self._l7_data[u"server"][u"tcp"][u"accepted_flows"] = None
                self._l7_data[u"server"][u"tcp"][u"connects"] = None
                self._l7_data[u"server"][u"tcp"][u"closed_flows"] = None
            else:
                logger.warn(u"Unsupported T-Rex ASTF traffic profile!")
            index = 0
            for line in stdout.splitlines():
                if f"Xstats snapshot {index}: " in line:
                    xstats[index] = line[19:]
                    index += 1
                if index == 2:
                    break
            self._xstats = tuple(xstats)
        else:
            self._target_duration = duration
            self._duration = computed_duration
            self._parse_traffic_results(stdout)

    def trex_stl_start_remote_exec(self, duration, rate, async_call=False):
        """Execute T-Rex STL script on remote node over ssh to start running
        traffic.

        In sync mode, measurement results are stored internally.
        In async mode, initial data including xstats are stored internally.

        Mode-unaware code (e.g. in search algorithms) works with transactions.
        To keep the logic simple, multiplier is set to that value.
        As bidirectional traffic profiles send packets in both directions,
        they are treated as transactions with two packets (one per direction).

        :param duration: Time expressed in seconds for how long to send traffic.
        :param rate: Traffic rate in transactions per second.
        :param async_call: If enabled then don't wait for all incoming traffic.
        :type duration: float
        :type rate: str
        :type async_call: bool
        :raises RuntimeError: In case of T-Rex driver issue.
        """
        self.check_mode(TrexMode.STL)
        p_0, p_1 = (1, 0) if self._ifaces_reordered else (0, 1)
        if not isinstance(duration, (float, int)):
            duration = float(duration)
        if self.duration_limit:
            duration = min(duration, self.duration_limit)

        command_line = OptionString().add(u"python3")
        dirname = f"{Constants.REMOTE_FW_DIR}/GPL/tools/trex"
        command_line.add(f"'{dirname}/trex_stl_profile.py'")
        command_line.change_prefix(u"--")
        dirname = f"{Constants.REMOTE_FW_DIR}/GPL/traffic_profiles/trex"
        command_line.add_with_value(
            u"profile", f"'{dirname}/{self.traffic_profile}.py'"
        )
        command_line.add_with_value(u"duration", f"{duration!r}")
        command_line.add_with_value(u"frame_size", self.frame_size)
        command_line.add_with_value(u"rate", f"{rate!r}")
        command_line.add_with_value(u"port_0", p_0)
        command_line.add_with_value(u"port_1", p_1)
        command_line.add_with_value(
            u"traffic_directions", self.traffic_directions
        )
        command_line.add_if(u"async_start", async_call)
        command_line.add_if(u"latency", self.use_latency)
        command_line.add_if(u"force", Constants.TREX_SEND_FORCE)

        # TODO: This is ugly. Handle parsing better.
        self._start_time = time.monotonic()
        self._rate = float(rate[:-3]) if u"pps" in rate else float(rate)
        stdout, _ = exec_cmd_no_error(
            self._node, command_line, timeout=int(duration) + 60,
            message=u"T-Rex STL runtime error"
        )

        if async_call:
            # no result
            self._target_duration = None
            self._duration = None
            self._received = None
            self._sent = None
            self._loss = None
            self._latency = None

            xstats = [None, None]
            index = 0
            for line in stdout.splitlines():
                if f"Xstats snapshot {index}: " in line:
                    xstats[index] = line[19:]
                    index += 1
                if index == 2:
                    break
            self._xstats = tuple(xstats)
        else:
            self._target_duration = duration
            self._duration = duration
            self._parse_traffic_results(stdout)

    def send_traffic_on_tg(
            self,
            duration,
            rate,
            frame_size,
            traffic_profile,
            async_call=False,
            ppta=1,
            traffic_directions=2,
            transaction_duration=0.0,
            transaction_scale=0,
            transaction_type=u"packet",
            duration_limit=0.0,
            use_latency=False,
        ):
        """Send traffic from all configured interfaces on TG.

        In async mode, xstats is stored internally,
        to enable getting correct result when stopping the traffic.
        In both modes, stdout is returned,
        but _parse_traffic_results only works in sync output.

        Note that traffic generator uses DPDK driver which might
        reorder port numbers based on wiring and PCI numbering.
        This method handles that, so argument values are invariant,
        but you can see swapped valued in debug logs.

        When transaction_scale is specified, the duration value is ignored
        and the needed time is computed. For cases where this results in
        to too long measurement (e.g. teardown trial with small rate),
        duration_limit is applied (of non-zero), so the trial is stopped sooner.

        Bidirectional STL profiles are treated as transactions with two packets.

        :param duration: Duration of test traffic generation in seconds.
        :param rate: Traffic rate in transactions per second.
        :param frame_size: Frame size (L2) in Bytes.
        :param traffic_profile: Module name as a traffic profile identifier.
            See GPL/traffic_profiles/trex for implemented modules.
        :param async_call: Async mode.
        :param ppta: Packets per transaction, aggregated over directions.
            Needed for udp_pps which does not have a good transaction counter,
            so we need to compute expected number of packets.
            Default: 1.
        :param traffic_directions: Traffic is bi- (2) or uni- (1) directional.
            Default: 2
        :param transaction_duration: Total expected time to close transaction.
        :param transaction_scale: Number of transactions to perform.
            0 (default) means unlimited.
        :param transaction_type: An identifier specifying which counters
            and formulas to use when computing attempted and failed
            transactions. Default: "packet".
        :param duration_limit: Zero or maximum limit for computed (or given)
            duration.
        :param use_latency: Whether to measure latency during the trial.
            Default: False.
        :type duration: float
        :type rate: float
        :type frame_size: str
        :type traffic_profile: str
        :type async_call: bool
        :type ppta: int
        :type traffic_directions: int
        :type transaction_duration: float
        :type transaction_scale: int
        :type transaction_type: str
        :type duration_limit: float
        :type use_latency: bool
        :returns: TG results.
        :rtype: str
        :raises ValueError: If TG traffic profile is not supported.
        """
        self.set_rate_provider_defaults(
            frame_size=frame_size,
            traffic_profile=traffic_profile,
            ppta=ppta,
            traffic_directions=traffic_directions,
            transaction_duration=transaction_duration,
            transaction_scale=transaction_scale,
            transaction_type=transaction_type,
            duration_limit=duration_limit,
            use_latency=use_latency,
        )
        self._send_traffic_on_tg_internal(duration, rate, async_call)

    def _send_traffic_on_tg_internal(self, duration, rate, async_call=False):
        """Send traffic from all configured interfaces on TG.

        This is an internal function, it assumes set_rate_provider_defaults
        has been called to remember most values.
        The reason why need to remember various values is that
        the traffic can be asynchronous, and parsing needs those values.
        The reason why this is is a separate function from the one
        which calls set_rate_provider_defaults is that some search algorithms
        need to specify their own values, and we do not want the measure call
        to overwrite them with defaults.

        :param duration: Duration of test traffic generation in seconds.
        :param rate: Traffic rate in transactions per second.
        :param async_call: Async mode.
        :type duration: float
        :type rate: float
        :type async_call: bool
        :returns: TG results.
        :rtype: str
        :raises ValueError: If TG traffic profile is not supported.
        """
        subtype = check_subtype(self._node)
        if subtype == NodeSubTypeTG.TREX:
            if u"trex-astf" in self.traffic_profile:
                self.trex_astf_start_remote_exec(
                    duration, float(rate), async_call
                )
            elif u"trex-stl" in self.traffic_profile:
                unit_rate_str = str(rate) + u"pps"
                # TODO: Suport transaction_scale et al?
                self.trex_stl_start_remote_exec(
                    duration, unit_rate_str, async_call
                )
            else:
                raise ValueError(u"Unsupported T-Rex traffic profile!")

        return self._result

    def no_traffic_loss_occurred(self):
        """Fail if loss occurred in traffic run.

        :returns: nothing
        :raises Exception: If loss occured.
        """
        if self._loss is None:
            raise RuntimeError(u"The traffic generation has not been issued")
        if self._loss != u"0":
            raise RuntimeError(f"Traffic loss occurred: {self._loss}")

    def fail_if_no_traffic_forwarded(self):
        """Fail if no traffic forwarded.

        TODO: Check number of passed transactions instead.

        :returns: nothing
        :raises Exception: If no traffic forwarded.
        """
        if self._received is None:
            raise RuntimeError(u"The traffic generation has not been issued")
        if self._received == u"0":
            raise RuntimeError(u"No traffic forwarded")

    def partial_traffic_loss_accepted(
            self, loss_acceptance, loss_acceptance_type):
        """Fail if loss is higher then accepted in traffic run.

        :param loss_acceptance: Permitted drop ratio or frames count.
        :param loss_acceptance_type: Type of permitted loss.
        :type loss_acceptance: float
        :type loss_acceptance_type: LossAcceptanceType
        :returns: nothing
        :raises Exception: If loss is above acceptance criteria.
        """
        if self._loss is None:
            raise Exception(u"The traffic generation has not been issued")

        if loss_acceptance_type == u"percentage":
            loss = (float(self._loss) / float(self._sent)) * 100
        elif loss_acceptance_type == u"frames":
            loss = float(self._loss)
        else:
            raise Exception(u"Loss acceptance type not supported")

        if loss > float(loss_acceptance):
            raise Exception(
                f"Traffic loss {loss} above loss acceptance: {loss_acceptance}"
            )

    def _parse_traffic_results(self, stdout):
        """Parse stdout of scripts into fields of self.

        Block of code to reuse, by sync start, or stop after async.

        :param stdout: Text containing the standard output.
        :type stdout: str
        """
        subtype = check_subtype(self._node)
        if subtype == NodeSubTypeTG.TREX:
            # Last line from console output
            line = stdout.splitlines()[-1]
            results = line.split(u";")
            if results[-1] in (u" ", u""):
                results.pop(-1)
            self._result = dict()
            for result in results:
                key, value = result.split(u"=", maxsplit=1)
                self._result[key.strip()] = value
            logger.info(f"TrafficGen results:\n{self._result}")
            self._received = int(self._result.get(u"total_received"), 0)
            self._sent = int(self._result.get(u"total_sent", 0))
            self._loss = int(self._result.get(u"frame_loss", 0))
            self._approximated_duration = \
                self._result.get(u"approximated_duration", 0.0)
            if u"manual" not in str(self._approximated_duration):
                self._approximated_duration = float(self._approximated_duration)
            self._latency = list()
            self._latency.append(self._result.get(u"latency_stream_0(usec)"))
            self._latency.append(self._result.get(u"latency_stream_1(usec)"))
            if self._mode == TrexMode.ASTF:
                self._l7_data = dict()
                self._l7_data[u"client"] = dict()
                self._l7_data[u"client"][u"sent"] = \
                    int(self._result.get(u"client_sent", 0))
                self._l7_data[u"client"][u"received"] = \
                    int(self._result.get(u"client_received", 0))
                self._l7_data[u"client"][u"active_flows"] = \
                    int(self._result.get(u"client_active_flows", 0))
                self._l7_data[u"client"][u"established_flows"] = \
                    int(self._result.get(u"client_established_flows", 0))
                self._l7_data[u"client"][u"traffic_duration"] = \
                    float(self._result.get(u"client_traffic_duration", 0.0))
                self._l7_data[u"client"][u"err_rx_throttled"] = \
                    int(self._result.get(u"client_err_rx_throttled", 0))
                self._l7_data[u"client"][u"err_c_nf_throttled"] = \
                    int(self._result.get(u"client_err_nf_throttled", 0))
                self._l7_data[u"client"][u"err_flow_overflow"] = \
                    int(self._result.get(u"client_err_flow_overflow", 0))
                self._l7_data[u"server"] = dict()
                self._l7_data[u"server"][u"active_flows"] = \
                    int(self._result.get(u"server_active_flows", 0))
                self._l7_data[u"server"][u"established_flows"] = \
                    int(self._result.get(u"server_established_flows", 0))
                self._l7_data[u"server"][u"traffic_duration"] = \
                    float(self._result.get(u"server_traffic_duration", 0.0))
                self._l7_data[u"server"][u"err_rx_throttled"] = \
                    int(self._result.get(u"client_err_rx_throttled", 0))
                if u"udp" in self.traffic_profile:
                    self._l7_data[u"client"][u"udp"] = dict()
                    self._l7_data[u"client"][u"udp"][u"connects"] = \
                        int(self._result.get(u"client_udp_connects", 0))
                    self._l7_data[u"client"][u"udp"][u"closed_flows"] = \
                        int(self._result.get(u"client_udp_closed", 0))
                    self._l7_data[u"client"][u"udp"][u"tx_bytes"] = \
                        int(self._result.get(u"client_udp_tx_bytes", 0))
                    self._l7_data[u"client"][u"udp"][u"rx_bytes"] = \
                        int(self._result.get(u"client_udp_rx_bytes", 0))
                    self._l7_data[u"client"][u"udp"][u"tx_packets"] = \
                        int(self._result.get(u"client_udp_tx_packets", 0))
                    self._l7_data[u"client"][u"udp"][u"rx_packets"] = \
                        int(self._result.get(u"client_udp_rx_packets", 0))
                    self._l7_data[u"client"][u"udp"][u"keep_drops"] = \
                        int(self._result.get(u"client_udp_keep_drops", 0))
                    self._l7_data[u"client"][u"udp"][u"err_cwf"] = \
                        int(self._result.get(u"client_err_cwf", 0))
                    self._l7_data[u"server"][u"udp"] = dict()
                    self._l7_data[u"server"][u"udp"][u"accepted_flows"] = \
                        int(self._result.get(u"server_udp_accepts", 0))
                    self._l7_data[u"server"][u"udp"][u"closed_flows"] = \
                        int(self._result.get(u"server_udp_closed", 0))
                    self._l7_data[u"server"][u"udp"][u"tx_bytes"] = \
                        int(self._result.get(u"server_udp_tx_bytes", 0))
                    self._l7_data[u"server"][u"udp"][u"rx_bytes"] = \
                        int(self._result.get(u"server_udp_rx_bytes", 0))
                    self._l7_data[u"server"][u"udp"][u"tx_packets"] = \
                        int(self._result.get(u"server_udp_tx_packets", 0))
                    self._l7_data[u"server"][u"udp"][u"rx_packets"] = \
                        int(self._result.get(u"server_udp_rx_packets", 0))
                elif u"tcp" in self.traffic_profile:
                    self._l7_data[u"client"][u"tcp"] = dict()
                    self._l7_data[u"client"][u"tcp"][u"initiated_flows"] = \
                        int(self._result.get(u"client_tcp_connect_inits", 0))
                    self._l7_data[u"client"][u"tcp"][u"connects"] = \
                        int(self._result.get(u"client_tcp_connects", 0))
                    self._l7_data[u"client"][u"tcp"][u"closed_flows"] = \
                        int(self._result.get(u"client_tcp_closed", 0))
                    self._l7_data[u"client"][u"tcp"][u"connattempt"] = \
                        int(self._result.get(u"client_tcp_connattempt", 0))
                    self._l7_data[u"client"][u"tcp"][u"tx_bytes"] = \
                        int(self._result.get(u"client_tcp_tx_bytes", 0))
                    self._l7_data[u"client"][u"tcp"][u"rx_bytes"] = \
                        int(self._result.get(u"client_tcp_rx_bytes", 0))
                    self._l7_data[u"server"][u"tcp"] = dict()
                    self._l7_data[u"server"][u"tcp"][u"accepted_flows"] = \
                        int(self._result.get(u"server_tcp_accepts", 0))
                    self._l7_data[u"server"][u"tcp"][u"connects"] = \
                        int(self._result.get(u"server_tcp_connects", 0))
                    self._l7_data[u"server"][u"tcp"][u"closed_flows"] = \
                        int(self._result.get(u"server_tcp_closed", 0))
                    self._l7_data[u"server"][u"tcp"][u"tx_bytes"] = \
                        int(self._result.get(u"server_tcp_tx_bytes", 0))
                    self._l7_data[u"server"][u"tcp"][u"rx_bytes"] = \
                        int(self._result.get(u"server_tcp_rx_bytes", 0))

    def get_measurement_result(self):
        """Return the result of last measurement as ReceiveRateMeasurement.

        Separate function, as measurements can end either by time
        or by explicit call, this is the common block at the end.

        The target_tr field of ReceiveRateMeasurement is in
        transactions per second. Transmit count and loss count units
        depend on the transaction type. Usually they are in transactions
        per second, or aggregate packets per second.

        TODO: Fail on running or already reported measurement.

        :returns: Structure containing the result of the measurement.
        :rtype: ReceiveRateMeasurement
        """
        try:
            # Client duration seems to include a setup period
            # where TRex does not send any packets yet.
            # Server duration does not include it.
            server_data = self._l7_data[u"server"]
            approximated_duration = float(server_data[u"traffic_duration"])
        except (KeyError, AttributeError, ValueError, TypeError):
            approximated_duration = None
        try:
            if not approximated_duration:
                approximated_duration = float(self._approximated_duration)
        except ValueError:  # "manual"
            approximated_duration = None
        if not approximated_duration:
            if self._duration and self._duration > 0:
                # Known recomputed or target duration.
                approximated_duration = self._duration
            else:
                # It was an explicit stop.
                if not self._stop_time:
                    raise RuntimeError(u"Unable to determine duration.")
                approximated_duration = self._stop_time - self._start_time
        target_duration = self._target_duration
        if not target_duration:
            target_duration = approximated_duration
        transmit_rate = self._rate
        if self.transaction_type == u"packet":
            partial_attempt_count = self._sent
            expected_attempt_count = self._sent
            fail_count = self._loss
        elif self.transaction_type == u"udp_cps":
            if not self.transaction_scale:
                raise RuntimeError(u"Add support for no-limit udp_cps.")
            partial_attempt_count = self._l7_data[u"client"][u"sent"]
            # We do not care whether TG is slow, it should have attempted all.
            expected_attempt_count = self.transaction_scale
            pass_count = self._l7_data[u"client"][u"received"]
            fail_count = expected_attempt_count - pass_count
        elif self.transaction_type == u"tcp_cps":
            if not self.transaction_scale:
                raise RuntimeError(u"Add support for no-limit tcp_cps.")
            ctca = self._l7_data[u"client"][u"tcp"][u"connattempt"]
            partial_attempt_count = ctca
            # We do not care whether TG is slow, it should have attempted all.
            expected_attempt_count = self.transaction_scale
            # TODO: Is there a better packet-based counter?
            pass_count = self._l7_data[u"server"][u"tcp"][u"connects"]
            fail_count = expected_attempt_count - pass_count
        elif self.transaction_type == u"udp_pps":
            if not self.transaction_scale:
                raise RuntimeError(u"Add support for no-limit udp_pps.")
            partial_attempt_count = self._sent
            expected_attempt_count = self.transaction_scale * self.ppta
            fail_count = self._loss + (expected_attempt_count - self._sent)
        elif self.transaction_type == u"tcp_pps":
            if not self.transaction_scale:
                raise RuntimeError(u"Add support for no-limit tcp_pps.")
            partial_attempt_count = self._sent
            expected_attempt_count = self.transaction_scale * self.ppta
            # One loss-like scenario happens when TRex receives all packets
            # on L2 level, but is not fast enough to process them all
            # at L7 level, which leads to retransmissions.
            # Those manifest as opackets larger than expected.
            # A simple workaround is to add absolute difference.
            # Probability of retransmissions exactly cancelling
            # packets unsent due to duration stretching is quite low.
            fail_count = self._loss + abs(expected_attempt_count - self._sent)
        else:
            raise RuntimeError(f"Unknown parsing {self.transaction_type!r}")
        if fail_count < 0 and not self.negative_loss:
            fail_count = 0
        measurement = ReceiveRateMeasurement(
            duration=target_duration,
            target_tr=transmit_rate,
            transmit_count=expected_attempt_count,
            loss_count=fail_count,
            approximated_duration=approximated_duration,
            partial_transmit_count=partial_attempt_count,
        )
        measurement.latency = self.get_latency_int()
        return measurement

    def measure(self, duration, transmit_rate):
        """Run trial measurement, parse and return results.

        The input rate is for transactions. Stateles bidirectional traffic
        is understood as sequence of (asynchronous) transactions,
        two packets each.

        The result units depend on test type, generally
        the count either transactions or packets (aggregated over directions).

        Optionally, this method sleeps if measurement finished before
        the time specified as duration.

        :param duration: Trial duration [s].
        :param transmit_rate: Target rate in transactions per second.
        :type duration: float
        :type transmit_rate: float
        :returns: Structure containing the result of the measurement.
        :rtype: ReceiveRateMeasurement
        :raises RuntimeError: If TG is not set or if node is not TG
            or if subtype is not specified.
        :raises NotImplementedError: If TG is not supported.
        """
        duration = float(duration)
        time_start = time.monotonic()
        time_stop = time_start + duration
        if self.resetter:
            self.resetter()
        self._send_traffic_on_tg_internal(
            duration=duration,
            rate=transmit_rate,
            async_call=False,
        )
        result = self.get_measurement_result()
        logger.debug(f"trial measurement result: {result!r}")
        # In PLRsearch, computation needs the specified time to complete.
        if self.sleep_till_duration:
            sleeptime = time_stop - time.monotonic()
            if sleeptime > 0.0:
                # TODO: Sometimes we have time to do additional trials here,
                # adapt PLRsearch to accept all the results.
                time.sleep(sleeptime)
        return result

    def set_rate_provider_defaults(
            self,
            frame_size,
            traffic_profile,
            ppta=1,
            resetter=None,
            traffic_directions=2,
            transaction_duration=0.0,
            transaction_scale=0,
            transaction_type=u"packet",
            duration_limit=0.0,
            negative_loss=True,
            sleep_till_duration=False,
            use_latency=False,
        ):
        """Store values accessed by measure().

        :param frame_size: Frame size identifier or value [B].
        :param traffic_profile: Module name as a traffic profile identifier.
            See GPL/traffic_profiles/trex for implemented modules.
        :param ppta: Packets per transaction, aggregated over directions.
            Needed for udp_pps which does not have a good transaction counter,
            so we need to compute expected number of packets.
            Default: 1.
        :param resetter: Callable to reset DUT state for repeated trials.
        :param traffic_directions: Traffic from packet counting point of view
            is bi- (2) or uni- (1) directional.
            Default: 2
        :param transaction_duration: Total expected time to close transaction.
        :param transaction_scale: Number of transactions to perform.
            0 (default) means unlimited.
        :param transaction_type: An identifier specifying which counters
            and formulas to use when computing attempted and failed
            transactions. Default: "packet".
            TODO: Does this also specify parsing for the measured duration?
        :param duration_limit: Zero or maximum limit for computed (or given)
            duration.
        :param negative_loss: If false, negative loss is reported as zero loss.
        :param sleep_till_duration: If true and measurement returned faster,
            sleep until it matches duration. Needed for PLRsearch.
        :param use_latency: Whether to measure latency during the trial.
            Default: False.
        :type frame_size: str or int
        :type traffic_profile: str
        :type ppta: int
        :type resetter: Optional[Callable[[], None]]
        :type traffic_directions: int
        :type transaction_duration: float
        :type transaction_scale: int
        :type transaction_type: str
        :type duration_limit: float
        :type negative_loss: bool
        :type sleep_till_duration: bool
        :type use_latency: bool
        """
        self.frame_size = frame_size
        self.traffic_profile = str(traffic_profile)
        self.resetter = resetter
        self.ppta = ppta
        self.traffic_directions = int(traffic_directions)
        self.transaction_duration = float(transaction_duration)
        self.transaction_scale = int(transaction_scale)
        self.transaction_type = str(transaction_type)
        self.duration_limit = float(duration_limit)
        self.negative_loss = bool(negative_loss)
        self.sleep_till_duration = bool(sleep_till_duration)
        self.use_latency = bool(use_latency)


class OptimizedSearch:
    """Class to be imported as Robot Library, containing search keywords.

    Aside of setting up measurer and forwarding arguments,
    the main business is to translate min/max rate from unidir to aggregate.
    """

    @staticmethod
    def perform_optimized_ndrpdr_search(
            frame_size,
            traffic_profile,
            minimum_transmit_rate,
            maximum_transmit_rate,
            packet_loss_ratio=0.005,
            final_relative_width=0.005,
            final_trial_duration=30.0,
            initial_trial_duration=1.0,
            number_of_intermediate_phases=2,
            timeout=720.0,
            doublings=1,
            ppta=1,
            resetter=None,
            traffic_directions=2,
            transaction_duration=0.0,
            transaction_scale=0,
            transaction_type=u"packet",
            use_latency=False,
    ):
        """Setup initialized TG, perform optimized search, return intervals.

        If transaction_scale is nonzero, all non-init trial durations
        are set to 2.0 (as they do not affect the real trial duration)
        and zero intermediate phases are used.
        The initial phase still uses 1.0 seconds, to force remeasurement.
        That makes initial phase act as a warmup.

        :param frame_size: Frame size identifier or value [B].
        :param traffic_profile: Module name as a traffic profile identifier.
            See GPL/traffic_profiles/trex for implemented modules.
        :param minimum_transmit_rate: Minimal load in transactions per second.
        :param maximum_transmit_rate: Maximal load in transactions per second.
        :param packet_loss_ratio: Fraction of packets lost, for PDR [1].
        :param final_relative_width: Final lower bound transmit rate
            cannot be more distant that this multiple of upper bound [1].
        :param final_trial_duration: Trial duration for the final phase [s].
        :param initial_trial_duration: Trial duration for the initial phase
            and also for the first intermediate phase [s].
        :param number_of_intermediate_phases: Number of intermediate phases
            to perform before the final phase [1].
        :param timeout: The search will fail itself when not finished
            before this overall time [s].
        :param doublings: How many doublings to do in external search step.
            Default 1 is suitable for fairly stable tests,
            less stable tests might get better overal duration with 2 or more.
        :param ppta: Packets per transaction, aggregated over directions.
            Needed for udp_pps which does not have a good transaction counter,
            so we need to compute expected number of packets.
            Default: 1.
        :param resetter: Callable to reset DUT state for repeated trials.
        :param traffic_directions: Traffic is bi- (2) or uni- (1) directional.
            Default: 2
        :param transaction_duration: Total expected time to close transaction.
        :param transaction_scale: Number of transactions to perform.
            0 (default) means unlimited.
        :param transaction_type: An identifier specifying which counters
            and formulas to use when computing attempted and failed
            transactions. Default: "packet".
        :param use_latency: Whether to measure latency during the trial.
            Default: False.
        :type frame_size: str or int
        :type traffic_profile: str
        :type minimum_transmit_rate: float
        :type maximum_transmit_rate: float
        :type packet_loss_ratio: float
        :type final_relative_width: float
        :type final_trial_duration: float
        :type initial_trial_duration: float
        :type number_of_intermediate_phases: int
        :type timeout: float
        :type doublings: int
        :type ppta: int
        :type resetter: Optional[Callable[[], None]]
        :type traffic_directions: int
        :type transaction_duration: float
        :type transaction_scale: int
        :type transaction_type: str
        :type use_latency: bool
        :returns: Structure containing narrowed down NDR and PDR intervals
            and their measurements.
        :rtype: NdrPdrResult
        :raises RuntimeError: If total duration is larger than timeout.
        """
        # we need instance of TrafficGenerator instantiated by Robot Framework
        # to be able to use trex_stl-*()
        tg_instance = BuiltIn().get_library_instance(
            u"resources.libraries.python.TrafficGenerator"
        )
        # Overrides for fixed transaction amount.
        # TODO: Move to robot code? We have two call sites, so this saves space,
        #       even though this is surprising for log readers.
        if transaction_scale:
            initial_trial_duration = 1.0
            final_trial_duration = 2.0
            number_of_intermediate_phases = 0
            timeout = 3600.0
        tg_instance.set_rate_provider_defaults(
            frame_size=frame_size,
            traffic_profile=traffic_profile,
            sleep_till_duration=False,
            ppta=ppta,
            resetter=resetter,
            traffic_directions=traffic_directions,
            transaction_duration=transaction_duration,
            transaction_scale=transaction_scale,
            transaction_type=transaction_type,
            use_latency=use_latency,
        )
        algorithm = MultipleLossRatioSearch(
            measurer=tg_instance,
            final_trial_duration=final_trial_duration,
            final_relative_width=final_relative_width,
            number_of_intermediate_phases=number_of_intermediate_phases,
            initial_trial_duration=initial_trial_duration,
            timeout=timeout,
            doublings=doublings,
        )
        result = algorithm.narrow_down_ndr_and_pdr(
            min_rate=minimum_transmit_rate,
            max_rate=maximum_transmit_rate,
            packet_loss_ratio=packet_loss_ratio,
        )
        return result

    @staticmethod
    def perform_soak_search(
            frame_size,
            traffic_profile,
            minimum_transmit_rate,
            maximum_transmit_rate,
            plr_target=1e-7,
            tdpt=0.1,
            initial_count=50,
            timeout=7200.0,
            ppta=1,
            resetter=None,
            trace_enabled=False,
            traffic_directions=2,
            transaction_duration=0.0,
            transaction_scale=0,
            transaction_type=u"packet",
            use_latency=False,
    ):
        """Setup initialized TG, perform soak search, return avg and stdev.

        :param frame_size: Frame size identifier or value [B].
        :param traffic_profile: Module name as a traffic profile identifier.
            See GPL/traffic_profiles/trex for implemented modules.
        :param minimum_transmit_rate: Minimal load in transactions per second.
        :param maximum_transmit_rate: Maximal load in transactions per second.
        :param plr_target: Fraction of packets lost to achieve [1].
        :param tdpt: Trial duration per trial.
            The algorithm linearly increases trial duration with trial number,
            this is the increment between succesive trials, in seconds.
        :param initial_count: Offset to apply before the first trial.
            For example initial_count=50 makes first trial to be 51*tdpt long.
            This is needed because initial "search" phase of integrator
            takes significant time even without any trial results.
        :param timeout: The search will stop after this overall time [s].
        :param ppta: Packets per transaction, aggregated over directions.
            Needed for udp_pps which does not have a good transaction counter,
            so we need to compute expected number of packets.
            Default: 1.
        :param resetter: Callable to reset DUT state for repeated trials.
        :param trace_enabled: True if trace enabled else False.
            This is very verbose tracing on numeric computations,
            do not use in production.
            Default: False
        :param traffic_directions: Traffic is bi- (2) or uni- (1) directional.
            Default: 2
        :param transaction_duration: Total expected time to close transaction.
        :param transaction_scale: Number of transactions to perform.
            0 (default) means unlimited.
        :param transaction_type: An identifier specifying which counters
            and formulas to use when computing attempted and failed
            transactions. Default: "packet".
        :param use_latency: Whether to measure latency during the trial.
            Default: False.
        :type frame_size: str or int
        :type traffic_profile: str
        :type minimum_transmit_rate: float
        :type maximum_transmit_rate: float
        :type plr_target: float
        :type initial_count: int
        :type timeout: float
        :type ppta: int
        :type resetter: Optional[Callable[[], None]]
        :type trace_enabled: bool
        :type traffic_directions: int
        :type transaction_duration: float
        :type transaction_scale: int
        :type transaction_type: str
        :type use_latency: bool
        :returns: Average and stdev of estimated aggregate rate giving PLR.
        :rtype: 2-tuple of float
        """
        tg_instance = BuiltIn().get_library_instance(
            u"resources.libraries.python.TrafficGenerator"
        )
        # Overrides for fixed transaction amount.
        # TODO: Move to robot code? We have a single call site
        #       but MLRsearch has two and we want the two to be used similarly.
        if transaction_scale:
            timeout = 7200.0
        tg_instance.set_rate_provider_defaults(
            frame_size=frame_size,
            traffic_profile=traffic_profile,
            negative_loss=False,
            sleep_till_duration=True,
            ppta=ppta,
            resetter=resetter,
            traffic_directions=traffic_directions,
            transaction_duration=transaction_duration,
            transaction_scale=transaction_scale,
            transaction_type=transaction_type,
            use_latency=use_latency,
        )
        algorithm = PLRsearch(
            measurer=tg_instance,
            trial_duration_per_trial=tdpt,
            packet_loss_ratio_target=plr_target,
            trial_number_offset=initial_count,
            timeout=timeout,
            trace_enabled=trace_enabled,
        )
        result = algorithm.search(
            min_rate=minimum_transmit_rate,
            max_rate=maximum_transmit_rate,
        )
        return result