role_maker.py

#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
#
# 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.
"""Defination of Role Makers."""

from __future__ import print_function
import os

from paddle.fluid.core import Gloo

__all__ = [
    'Role', 'RoleMakerBase', 'MPISymetricRoleMaker', 'UserDefinedRoleMaker',
    'UserDefinedCollectiveRoleMaker', 'PaddleCloudRoleMaker', 'GeneralRoleMaker'
]


class Role:
    WORKER = 1
    SERVER = 2


class RoleMakerBase(object):
    """
    RoleMakerBase is a base class for assigning a role to current process
    in distributed training.
    A paddle developer can implement RoleMakerBase to design a role maker
    for worker or pserver assignment.
    """

    def __init__(self):
        self._worker_endpoints = []
        self._server_endpoints = []
        self._role_is_generated = False
        self._role = None
        self._current_id = -1

    def is_worker(self):
        """
        return is_worker() of current process
        """
        raise NotImplementedError("Please implement this method in child class")

    def is_server(self):
        """
        return is_server() of current process
        """
        raise NotImplementedError("Please implement this method in child class")

    def is_first_worker(self):
        """
        Check whether the node is the first instance of worker.
        Returns:
            bool: True if this is the first node of worker,
                  False if not.
        """
        raise NotImplementedError("Please implement this method in child class")

    def worker_num(self):
        """
        Get current total worker number.

        Returns:
            int: worker number
        """
        raise NotImplementedError("Please implement this method in child class")

    def worker_index(self):
        """
        Get current worker id.

        Returns:
            int: node id
        """
        raise NotImplementedError("Please implement this method in child class")

    def server_index(self):
        """
        Get current server id.

        Returns:
            int: node id
        """
        raise NotImplementedError("Please implement this method in child class")

    def get_trainer_endpoints(self):
        """
        return trainer endpoints
        """
        return self._worker_endpoints

    def get_pserver_endpoints(self):
        """
        return pserver endpoints
        """
        return self._server_endpoints

    def to_string(self):
        return "role: {}, current_id: {}, worker_endpoints: {}, server_endpoints: {}".format(
            self._role, self._current_id, self._worker_endpoints,
            self._server_endpoints)

    def all_gather(self, input):
        """
        all gather between trainers and pservers

        Args:
            input(int|float): input value

        Returns:
            return a list of values
        """
        print("warning: RoleMakerBase does not have all gather.")
        return None

    def all_reduce_worker(self, input, output, mode="sum"):
        """
        all reduce between trainers if current role is TRAINER,
        only support array of one dim.

        Args:
            input(list/numpy.array): array of one dim
            output(list/numpy.array): array of one dim
            mode(str): "sum" or "min" or "max"
        """
        print("warning: RoleMakerBase does not have all reduce worker.")

    def barrier_worker(self):
        """
        barrier between trainers if current role is TRAINER
        """
        print("warning: RoleMakerBase does not have barrier worker.")

    def barrier_all(self):
        """
        barrier between trainers if current role is PSERVER
        """
        print("warning: RoleMakerBase does not have barrier all.")


class MPIRoleMaker(RoleMakerBase):
    """
    MPIRoleMaker is a MPI-API based role maker which is a counter-part of K8SRoleMaker
    mpi4py will be used if a developer inherits MPIRoleMaker
    """

    def __init__(self):
        """Init."""
        super(MPIRoleMaker, self).__init__()
        from mpi4py import MPI
        self.MPI = MPI
        self._comm = MPI.COMM_WORLD
        self._node_type_comm = None
        self._ips = None
        self._ip = None

    def _get_rank(self):
        """Return rank."""
        self._rank = self._comm.Get_rank()
        return self._rank

    def _get_size(self):
        """Return size."""
        self._size = self._comm.Get_size()
        return self._size

    def _all_gather(self, obj):
        """
        all_gather(obj) will call MPI's allgather function
        """
        self._barrier_all()
        return self._comm.allgather(obj)

    def _worker_gather(self, obj):
        """
        worker_gather(obj) will call MPI's allgather function
        """
        if self.is_worker():
            self._node_type_comm.barrier()
            return self._node_type_comm.allgather(obj)
        return None

    def _barrier_all(self):
        """
        barrier_all() will call MPI's barrier_all function
        """
        self._comm.barrier()

    def _finalize(self):
        """
        finalize the current MPI instance.
        """
        self.MPI.Finalize()

    def _get_ips(self):
        """
        collect current distributed job's ip list
        """
        if not self._ips:
            self._ips = self._comm.allgather(self.get_local_ip())
        return self._ips

    def get_local_ip(self):
        """Return get local ip."""
        import socket
        self._ip = socket.gethostbyname(socket.gethostname())
        return self._ip

    def generate_role(self):
        """
        generate_role() should be called to identify current process's role
        """
        raise NotImplementedError("Please implement this method in child class")


class MPISymetricRoleMaker(MPIRoleMaker):
    """
    MPISymetricRoleMaker is designed for worker and server assignment
    under MPI. Typically, a worker and a server node will be appointed
    on each physical node. This role maker can be only used under MPI.
    """

    def __init__(self):
        """Init."""
        super(MPISymetricRoleMaker, self).__init__()
        self._node_type = None
        self._proc_per_node = 2
        self._pserver_rand_port = 0

    def _check_role_generation(self):
        """Check whether role has been generated."""
        if not self._role_is_generated:
            raise NameError("generate_role() should be called first")
        return True

    def all_gather(self, input):
        """
        all gather between trainers and pservers

        Args:
            input(int|float): input value

        Returns:
            return a list of values
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._all_gather(input)

    def all_reduce_worker(self, input, output, mode="sum"):
        """
        all reduce between trainers if current role is TRAINER,
        only support array of one dim.

        Args:
            input(list/numpy.array): array of one dim
            output(list/numpy.array): array of one dim
            mode(str): "sum" or "min" or "max"
        """
        if not self._role_is_generated:
            self.generate_role()
        if not self.is_worker():
            print("warning: current role is not worker in all_reduce_worker")
            return
        self._all_reduce(input, output, mode)

    def barrier_worker(self):
        """
        barrier between trainers if current role is TRAINER
        """
        if not self._role_is_generated:
            self.generate_role()
        if self.is_worker():
            self._node_type_comm.barrier()
        else:
            print("warning: current role is not worker in barrier_worker")

    def barrier_all(self):
        """
        barrier between trainers if current role is PSERVER
        """
        if not self._role_is_generated:
            self.generate_role()
        self._comm.barrier()

    def is_first_worker(self):
        """
        return whether current process is the first worker assigned by role maker
        """
        if self._check_role_generation():
            return self.is_worker() and 0 == self.worker_index()
        return False

    def get_pserver_endpoints(self):
        """
        get pserver endpoints
        
        Returns:
            endpoints(list): pserver endpoints
        """
        if self._pserver_rand_port <= 0:
            import random
            random.seed(self._server_num())
            # port will be randomly generated from 60001 to 63999
            # random seed is server num so that all nodes will get
            # the same port
            self._pserver_rand_port = random.randint(60001, 64000)
        endpoints = [
            x + ":" + str(self._pserver_rand_port)
            for x in self._server_endpoints
        ]
        return endpoints

    def worker_num(self):
        return self._worker_num()

    def is_worker(self):
        """
        return whether current process is worker assigned by role maker
        """
        if self._check_role_generation():
            return self._node_type == 1
        return False

    def is_server(self):
        """
        return whether current process is server assigned by role maker
        """
        if self._check_role_generation():
            return self._node_type == 0
        return False

    def _worker_num(self):
        """
        return the current number of worker
        """
        if self._check_role_generation():
            return self._get_size() / self._proc_per_node
        return 0

    def _server_num(self):
        """
        return the current number of server
        """
        if self._check_role_generation():
            return self._get_size() / self._proc_per_node
        else:
            self.generate_role()
            return self._get_size() / self._proc_per_node

    def worker_index(self):
        """
        return the index of worker
        """
        if self._check_role_generation():
            return self._rank / self._proc_per_node
        else:
            self.generate_role()
            return self._get_size() / 2

    def server_index(self):
        """
        return the index of server
        """
        if self._check_role_generation():
            return self._rank / self._proc_per_node
        else:
            self.generate_role()
            return self._get_size() / self._proc_per_node

    def _all_reduce(self, input, output, mode="sum"):
        """
        all reduce between trainers if current role is TRAINER,
        only support array of one dim.

        Args:
            input(list/numpy.array): array of one dim
            output(list/numpy.array): array of one dim
            mode(str): "sum" or "min" or "max"
        """
        if not self._role_is_generated:
            self.generate_role()
        if mode == "sum":
            mode = self.MPI.SUM
        elif mode == "max":
            mode = self.MPI.MAX
        elif mode == "min":
            mode = self.MPI.MIN
        else:
            raise ValueError("unknown mode: %s" % mode)
        self._node_type_comm.Allreduce(input, output, op=mode)

    def _barrier_worker(self):
        """
        barrier all workers in current distributed job
        """
        if self._check_role_generation():
            if self.is_worker():
                self._node_type_comm.barrier()
        else:
            raise Exception("You should check role generation first")

    def _barrier_server(self):
        """
        barrier all servers in current distributed job
        """
        if self._check_role_generation():
            if self.is_server():
                self._node_type_comm.barrier()
        else:
            raise Exception("You should check role generation first")

    def generate_role(self):
        """
        generate currently process's role
        """
        if not self._role_is_generated:
            # TODO(guru4elephant): only allow to be called once
            self._worker_endpoints = self._get_ips()[1::2]
            self._server_endpoints = self._get_ips()[::2]

            if 0 == self._get_rank() % self._proc_per_node % 2:
                self._node_type = 0
            else:
                self._node_type = 1
            self._node_type_comm = self._comm.Split(self._node_type)
            self._role_is_generated = True
        else:
            raise Exception("You should check role generation first")


class PaddleCloudRoleMaker(RoleMakerBase):
    """
    role maker for paddle cloud,
    base class is RoleMakerBase
    """

    def __init__(self, is_collective=False):
        super(PaddleCloudRoleMaker, self).__init__()
        self._role_is_generated = False
        self._is_collective = is_collective

    def generate_role(self):
        """Generate role."""
        if not self._role_is_generated:
            if not self._is_collective:
                try:
                    # Environment variable PADDLE_PSERVERS_IP_PORT_LIST must be set
                    # format: string(ip:port), eg. 127.0.0.1:6001
                    eplist = os.environ["PADDLE_PSERVERS_IP_PORT_LIST"].split(
                        ",")
                    # note that, we usually assign the same port to different ips
                    # if we run parameter server training in local mode
                    # port should be different in environment variables

                    trainers_num = int(os.environ["PADDLE_TRAINERS_NUM"])
                    training_role = os.environ["TRAINING_ROLE"]

                    if training_role not in ["TRAINER", "PSERVER"]:
                        raise ValueError(
                            "TRAINING_ROLE must be PSERVER or TRAINER")

                    if training_role == "TRAINER":
                        role = Role.WORKER
                        current_id = int(os.environ["PADDLE_TRAINER_ID"])
                    elif training_role == "PSERVER":
                        role = Role.SERVER
                        cur_ip = os.environ["POD_IP"]
                        curr_port = os.environ["PADDLE_PORT"]
                        curr_endpoint = ":".join([cur_ip, curr_port])
                        current_id = eplist.index(curr_endpoint)
                    else:
                        raise ValueError(
                            "TRAINING_ROLE must be PSERVER or TRAINER")
                except ValueError as ve:
                    raise ValueError(
                        "something wrong with PaddleCloud, please check environment"
                    )

                self._trainers_num = trainers_num
                self._server_endpoints = eplist
                self._role = role
                self._current_id = current_id
            else:
                self._current_id = int(os.getenv("PADDLE_TRAINER_ID", "0"))
                self._training_role = os.getenv("PADDLE_TRAINING_ROLE",
                                                "TRAINER")
                assert (self._training_role == "TRAINER")
                self._worker_endpoints = os.getenv("PADDLE_TRAINER_ENDPOINTS")
                self._current_endpoint = os.getenv("PADDLE_CURRENT_ENDPOINT")
                assert self._worker_endpoints is not None, "can't find PADDLE_TRAINER_ENDPOINTS"
                self._worker_endpoints = self._worker_endpoints.split(",")
                self._trainers_num = len(self._worker_endpoints)

            self._role_is_generated = True

    def get_pserver_endpoints(self):
        if not self._role_is_generated:
            self.generate_role()
        return self._server_endpoints

    def is_worker(self):
        if not self._role_is_generated:
            self.generate_role()
        return self._role == Role.WORKER

    def is_server(self):
        if not self._role_is_generated:
            self.generate_role()
        return self._role == Role.SERVER

    def is_first_worker(self):
        if not self._role_is_generated:
            self.generate_role()
        return self._role == Role.WORKER and self._current_id == 0

    def worker_index(self):
        if not self._role_is_generated:
            self.generate_role()
        return self._current_id

    def server_index(self):
        if not self._role_is_generated:
            self.generate_role()
        return self._current_id

    def worker_num(self):
        if not self._role_is_generated:
            self.generate_role()
        return self._trainers_num


class GeneralRoleMaker(RoleMakerBase):
    """
    This role maker is for general use, you can set os.environ to customize:
        PADDLE_PSERVERS_IP_PORT_LIST : all pservers' ip:port, separated by ','
        PADDLE_TRAINER_ENDPOINTS     : all trainers' ip:port, separated by ','
        TRAINING_ROLE                : TRAINER or PSERVER
        PADDLE_TRAINER_ID            : current trainer id (only for trainer),
                                       it is index in PADDLE_TRAINER_ENDPOINTS
        PADDLE_PSERVER_ID            : current pserver id (only for pserver)
                                       it is index in PADDLE_PSERVERS_IP_PORT_LIST
    """

    def __init__(self, **kwargs):
        super(RoleMakerBase, self).__init__()
        self._role_is_generated = False
        self._hdfs_name = kwargs.get("hdfs_name", "")
        self._hdfs_ugi = kwargs.get("hdfs_ugi", "")
        self._hdfs_path = kwargs.get("path", "")
        self._iface = self.__get_default_iface()
        # this environment variable can be empty
        self._prefix = os.getenv("SYS_JOB_ID", "")

    def generate_role(self):
        """
        generate role for general role maker
        """
        if not self._role_is_generated:
            eplist = os.environ["PADDLE_PSERVERS_IP_PORT_LIST"].split(",")
            training_role = os.environ["TRAINING_ROLE"]
            worker_endpoints = os.environ["PADDLE_TRAINER_ENDPOINTS"].split(",")
            trainers_num = len(worker_endpoints)
            if training_role not in ["TRAINER", "PSERVER"]:
                raise ValueError("TRAINING_ROLE must be PSERVER or TRAINER")
            if training_role == "TRAINER":
                role = Role.WORKER
                current_id = int(os.environ["PADDLE_TRAINER_ID"])
                self._node_type = 1
                self._cur_endpoint = worker_endpoints[current_id]
                gloo = Gloo()
                gloo.init(current_id,
                          len(worker_endpoints),
                          self._hdfs_path.rstrip("/") + "/trainer",
                          self._hdfs_name, self._hdfs_ugi, self._iface,
                          self._prefix)
                self._node_type_comm = gloo
            elif training_role == "PSERVER":
                role = Role.SERVER
                if os.environ.get("PADDLE_PSERVER_ID") is not None:
                    current_id = int(os.environ["PADDLE_PSERVER_ID"])
                    cur_endpoint = eplist[current_id]
                else:
                    # this is for compatible with paddlecloud
                    cur_ip = os.environ["POD_IP"]
                    cur_port = os.environ["PADDLE_PORT"]
                    cur_endpoint = ":".join([cur_ip, cur_port])
                    current_id = eplist.index(cur_endpoint)
                self._node_type = 0
                self._cur_endpoint = cur_endpoint
                gloo = Gloo()
                gloo.init(current_id,
                          len(eplist),
                          self._hdfs_path.rstrip("/") + "/pserver",
                          self._hdfs_name, self._hdfs_ugi, self._iface,
                          self._prefix)
                self._node_type_comm = gloo

            gloo = Gloo()
            all_list = worker_endpoints + eplist
            gloo.init(
                all_list.index(self._cur_endpoint),
                len(all_list),
                self._hdfs_path.rstrip("/") + "/all", self._hdfs_name,
                self._hdfs_ugi, self._iface, self._prefix)
            self._all_comm = gloo
            self._trainers_num = trainers_num
            self._server_endpoints = eplist
            self._role = role
            self._current_id = current_id
            self._rank = all_list.index(self._cur_endpoint)
            self._size = len(all_list)
            self._worker_endpoints = worker_endpoints
            self._role_is_generated = True

    def all_gather(self, input):
        """
        all gather between trainers and pservers

        Args:
            input(int|float): input value

        Returns:
            return a list of values
        """
        return self._all_gather(input)

    def all_reduce_worker(self, input, output, mode="sum"):
        """
        all reduce between trainers if current role is TRAINER,
        only support array of one dim.

        Args:
            input(list/numpy.array): array of one dim
            output(list/numpy.array): array of one dim
            mode(str): "sum" or "min" or "max"
        """
        if not self.is_worker():
            return
        self._all_reduce(input, output, mode)

    def barrier_worker(self):
        """
        barrier between trainers if current role is TRAINER
        """
        self._barrier_worker()

    def barrier_all(self):
        """
        barrier between trainers if current role is PSERVER
        """
        self._barrier_all()

    def get_local_endpoint(self):
        """
        get local endpoint of current process
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._cur_endpoint

    def get_trainer_endpoints(self):
        """
        get endpoint of all trainers
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._worker_endpoints

    def get_pserver_endpoints(self):
        """
        get endpoint of all pservers
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._server_endpoints

    def is_worker(self):
        """
        whether current process is worker
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._role == Role.WORKER

    def is_server(self):
        """
        whether current process is server
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._role == Role.SERVER

    def is_first_worker(self):
        """
        whether current process is worker of rank 0
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._role == Role.WORKER and self._current_id == 0

    def worker_index(self):
        """
        get index of current worker
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._current_id

    def server_index(self):
        """
        get index of current server
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._current_id

    def worker_num(self):
        """
        retrun the current number of worker
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._worker_num()

    def server_num(self):
        """
        return the current number of server
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._server_num()

    def _barrier_worker(self):
        """
        barrier all workers in current distributed job
        """
        if not self._role_is_generated:
            self.generate_role()
        if self.is_worker():
            self._node_type_comm.barrier()

    def _barrier_all(self):
        """
        barrier all workers and servers in current distributed job
        """
        if not self._role_is_generated:
            self.generate_role()
        self._all_comm.barrier()

    def _barrier_server(self):
        """
        barrier all servers in current distributed job
        """
        if not self._role_is_generated:
            self.generate_role()
        if self.is_server():
            self._node_type_comm.barrier()

    def _worker_num(self):
        """
        return the current number of worker
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._trainers_num

    def _server_num(self):
        """
        return the current number of server
        """
        if not self._role_is_generated:
            self.generate_role()
        return len(self._server_endpoints)

    def _finalize(self):
        """Default do nothing."""
        pass

    def _all_reduce(self, input, output, mode="sum"):
        """
        all reduce between all workers

        Args:
            input(list|numpy.array): array of one dim
            output(list|numpy.array): array of one dim
            mode(str): "sum" or "min" or "max"
        """
        if not self._role_is_generated:
            self.generate_role()
        input_list = [i for i in input]
        ans = self._node_type_comm.all_reduce(input_list, mode)
        for i in range(len(ans)):
            output[i] = ans[i]

    def _all_gather(self, obj):
        """
        gather between all workers and pservers
        """
        if not self._role_is_generated:
            self.generate_role()
        self._barrier_all()
        return self._all_comm.all_gather(obj)

    def _worker_gather(self, obj):
        """
        gather between all workers
        """
        if not self._role_is_generated:
            self.generate_role()
        if not self.is_worker():
            return None
        self._barrier_worker()
        return self._node_type_comm.all_gather(obj)

    def _get_rank(self):
        """
        get current rank in all workers and pservers
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._rank

    def _get_size(self):
        """
        get total num of all workers and pservers
        """
        if not self._role_is_generated:
            self.generate_role()
        return self._size

    def __get_default_iface(self):
        """
        get default physical interface
        """
        default1 = self.__get_default_iface_from_gateway()
        default2 = self.__get_default_iface_from_interfaces()
        return default2 if default1 == "lo" else default1

    def __get_default_iface_from_gateway(self):
        """
        get default physical interface
        """
        import netifaces
        gateways = netifaces.gateways()
        if gateways.get(netifaces.AF_INET) != None:
            gateway = gateways[netifaces.AF_INET]
            if len(gateway) > 0 and len(gateway[0]) > 1:
                return gateway[0][1]
        return "lo"

    def __get_default_iface_from_interfaces(self):
        """
        get default physical interface
        """
        import netifaces
        for intf_name in netifaces.interfaces():
            addresses = netifaces.ifaddresses(intf_name)
            if netifaces.AF_INET in addresses:
                ipv4_addresses = addresses[netifaces.AF_INET]
                for ipv4_address in ipv4_addresses:
                    if 'broadcast' in ipv4_address:
                        return intf_name
        return "lo"


class UserDefinedRoleMaker(RoleMakerBase):
    """
    UserDefinedRoleMaker is designed for worker and server assignment
    under manual. Typically, a worker and a server node will be appointed
    on each physical node, It can be assign by user.
    """

    def __init__(self,
                 current_id=0,
                 role=Role.WORKER,
                 worker_num=0,
                 server_endpoints=None):
        super(UserDefinedRoleMaker, self).__init__()

        if not isinstance(server_endpoints, list):
            raise TypeError("server_endpoints must be as string list")
        elif len(server_endpoints) <= 0:
            raise ValueError(
                "the length of server_endpoints list must be greater than 0")
        elif len(server_endpoints) != len(set(server_endpoints)):
            raise ValueError("server_endpoints can't have duplicate elements")
        else:
            for server_endpoint in server_endpoints:
                if not isinstance(server_endpoint, str):
                    raise TypeError(
                        "every element in server_endpoints list must be as string"
                    )
            self._server_endpoints = server_endpoints

        if role != Role.WORKER and role != Role.SERVER:
            raise TypeError("role must be as Role")
        else:
            self._role = role

        if not isinstance(current_id, int):
            raise TypeError("current_id must be as int")
        else:
            if current_id < 0:
                raise ValueError(
                    "current_id must be greater than or equal to 0")
            elif self._role == Role.SERVER and current_id >= len(
                    server_endpoints):
                raise ValueError(
                    "if role is Role.SERVER, current_id must be less than or equal to len(server_endpoints) - 1"
                )
            self._current_id = current_id

        if not isinstance(worker_num, int):
            raise TypeError("worker_num must be as int")
        else:
            if worker_num <= 0:
                raise ValueError("worker_num must be greater than 0")
            self._worker_num = worker_num

    def generate_role(self):
        self._role_is_generated = True

    def is_worker(self):
        return self._role == Role.WORKER

    def is_server(self):
        return self._role == Role.SERVER

    def is_first_worker(self):
        return self._role == Role.WORKER and self._current_id == 0

    def worker_index(self):
        return self._current_id

    def server_index(self):
        return self._current_id

    def worker_num(self):
        return self._worker_num


class UserDefinedCollectiveRoleMaker(RoleMakerBase):
    """
    UserDefinedCollectiveRoleMaker is designed for worker assignment
    under manual for collective mode.
    """

    def __init__(self, current_id=0, worker_endpoints=None):
        super(UserDefinedCollectiveRoleMaker, self).__init__()

        if not isinstance(worker_endpoints, list):
            raise TypeError("worker_endpoints must be as string list")
        elif len(worker_endpoints) <= 0:
            raise ValueError(
                "the length of worker_endpoints list must be greater than 0")
        elif len(worker_endpoints) != len(set(worker_endpoints)):
            raise ValueError("worker_endpoints can't have duplicate elements")
        else:
            for worker_endpoint in worker_endpoints:
                if not isinstance(worker_endpoint, str):
                    raise TypeError(
                        "every element in worker_endpoints list must be as string"
                    )
            self._worker_endpoints = worker_endpoints

        if not isinstance(current_id, int):
            raise TypeError("current_id must be as int")
        else:
            if current_id < 0:
                raise ValueError(
                    "current_id must be greater than or equal to 0")
            elif current_id >= len(worker_endpoints):
                raise ValueError(
                    "current_id must be less than or equal to len(worker_endpoints) - 1"
                )
            self._current_id = current_id

        self._worker_num = len(self._worker_endpoints)

    def generate_role(self):
        self._role_is_generated = True

    def is_worker(self):
        return True

    def is_first_worker(self):
        return self._current_id == 0

    def worker_index(self):
        return self._current_id

    def worker_num(self):
        return self._worker_num