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# Copyright (c) 2021 Red Hat, Inc.
#
# 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 re
import subprocess
class DpPortMapping:
"""Class used to retrieve and cache datapath port numbers to port names."""
MAX_REQUESTS = 2
def __init__(self):
self.cache_map = None
self.n_requests = 0
def get_map(self):
"""Get the cache map."""
self._get_mapping()
return self.cache_map
def set_map(self, cache_map):
"""Override the internal cache map."""
self.cache_map = cache_map
self.n_requests = self.MAX_REQUESTS
def _retry(self, func):
self._get_mapping()
result = func(self.cache_map)
if not result:
self._get_mapping(refresh=True)
return func(self.cache_map)
return result
def get_port_name(self, dp, port_no):
"""Get the port name from a port number."""
def _get_port_name(cache_map):
if not cache_map.get(dp):
return None
for name, num in cache_map[dp].items():
if num == port_no:
return name
return self._retry(_get_port_name)
def get_port_number(self, dp, port):
"""Get the port number from a port name."""
def _get_port_number(cache_map):
return cache_map.get(dp, {}).get(port, None)
return self._retry(_get_port_number)
def _get_mapping(self, refresh=False):
"""Get the datapath port mapping from the running OVS."""
if self.n_requests >= self.MAX_REQUESTS \
or (self.cache_map and not refresh):
return
self.n_requests += 1
try:
output = subprocess.check_output(
["ovs-appctl", "dpctl/show"], encoding="utf8"
).split("\n")
except subprocess.CalledProcessError:
output = ""
return
current_dp = None
self.cache_map = {}
for line in output:
match = re.match("^system@(.*):$", line)
if match:
current_dp = match.group(1)
match = re.match("^ port ([0-9]+): ([^ /]*)", line)
if match and current_dp:
try:
self.cache_map[current_dp][match.group(2)] = int(
match.group(1)
)
except KeyError:
self.cache_map[current_dp] = {
match.group(2): int(match.group(1))
}
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