Source code for nnabla_rl.hook

# Copyright 2020,2021 Sony Corporation.
# Copyright 2021 Sony Group Corporation.
#
# 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 abc import ABCMeta, abstractmethod


class Hook(metaclass=ABCMeta):
    '''
    Base class of hooks for Algorithm classes.

    Hook is called at every 'timing' iterations during the training.
    'timing' is specified at the beginning of the class instantiation.
    '''

    timing = 1

    def __init__(self, timing=1000):
        self._timing = timing

    def __call__(self, algorithm):
        if algorithm.iteration_num % self._timing != 0:
            return
        self.on_hook_called(algorithm)

    @abstractmethod
    def on_hook_called(self, algorithm):
        '''
        Called every "timing" iteration which is set on Hook's instance creation.
        Will run additional periodical operation (see each class' documentation) during the training.

        Args:
            algorithm (nnabla_rl.algorithm.Algorithm): Algorithm instance to perform additional operation.
        '''
        raise NotImplementedError