sma: add bdev QoS helper functions

import grpc

from spdk.rpc.client import JSONRPCException

from .common import format_volume_id

from .proto import sma_pb2

LIMIT_UNDEFINED = (1 << 64) - 1

class QosException(Exception):

    def __init__(self, code, message):

        self.code = code

        self.message = message

def set_volume_bdev_qos(client, params):

    class BdevLimit:

        def __init__(self, name, transform=lambda v: v):

            self.name = name

            self._transform = transform

        def get_value(self, value):

            return self._transform(value)

    supported_limits = {

            'rw_iops': BdevLimit('rw_ios_per_sec', lambda v: v * 1000),

            'rd_bandwidth': BdevLimit('r_mbytes_per_sec'),

            'wr_bandwidth': BdevLimit('w_mbytes_per_sec'),

            'rw_bandwidth': BdevLimit('rw_mbytes_per_sec')

    }

    # Check that none of the unsupported fields aren't set either

    if params.HasField('maximum'):

        for field, value in params.maximum.ListFields():

            if field.name in supported_limits.keys():

                continue

            if value != 0 and value != LIMIT_UNDEFINED:

                raise QosException(grpc.StatusCode.INVALID_ARGUMENT,

                                   f'Unsupported QoS limit: maximum.{field.name}')

    try:

        rpc_params = {'name': format_volume_id(params.volume_id)}

        for name, limit in supported_limits.items():

            value = getattr(params.maximum, name)

            if value != LIMIT_UNDEFINED:

                rpc_params[limit.name] = limit.get_value(value)

        client.call('bdev_set_qos_limit', rpc_params)

    except JSONRPCException:

        raise QosException(grpc.StatusCode.INTERNAL, 'Failed to set QoS')

def get_bdev_qos_capabilities():

    return sma_pb2.GetQosCapabilitiesResponse(

            max_volume_caps=sma_pb2.GetQosCapabilitiesResponse.QosCapabilities(

                rw_iops=True,

                rw_bandwidth=True,

                rd_bandwidth=True,

                wr_bandwidth=True

                ),

            )