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#
# -------------------------------------------------------------------------
# Copyright (c) 2015-2017 AT&T Intellectual Property
#
# 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.
#
# -------------------------------------------------------------------------
#
import math
from oslo_log import log
LOG = log.getLogger(__name__)
def compute_air_distance(_src, _dst):
"""Compute Air Distance
based on latitude and longitude
input: a pair of (lat, lon)s
output: air distance as km
"""
distance = 0.0
latency_score = 0.0
if _src == _dst:
return distance
radius = 6371.0 # km
dlat = math.radians(_dst[0] - _src[0])
dlon = math.radians(_dst[1] - _src[1])
a = math.sin(dlat / 2.0) * math.sin(dlat / 2.0) + \
math.cos(math.radians(_src[0])) * \
math.cos(math.radians(_dst[0])) * \
math.sin(dlon / 2.0) * math.sin(dlon / 2.0)
c = 2.0 * math.atan2(math.sqrt(a), math.sqrt(1.0 - a))
distance = radius * c
return distance
def compute_latency_score(_src,_dst, _region_group):
"""Compute the Network latency score between src and dst"""
earth_half_circumference = 20000
region_group_weight = _region_group.get(_dst[2])
if region_group_weight == 0 or region_group_weight is None :
LOG.debug("Computing the latency score based on distance between : ")
latency_score = compute_air_distance(_src,_dst)
elif _region_group > 0 :
LOG.debug("Computing the latency score ")
latency_score = compute_air_distance(_src, _dst) + region_group_weight * earth_half_circumference
LOG.debug("Finished Computing the latency score: "+str(latency_score))
return latency_score
def convert_km_to_miles(_km):
return _km * 0.621371
def convert_miles_to_km(_miles):
return _miles / 0.621371
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