# Copyright 2020 Alibaba Group Holding Limited. 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.
# =============================================================================
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import threading

class State(object):
  def __init__(self, value={}):
    self._values = value
    self._value_lock = threading.Lock()

  def put(self, key, value):
    with self._value_lock:
      self._values[key] = value

  def get(self, key):
    return self._values.get(key, 0)

  def inc(self, key, delta=1):
    with self._value_lock:
      self._values[key] = self._values.get(key, 0) + delta

class NodeState(State):
  pass

class EdgeState(State):
  pass

class DagState(State):
  pass
