from algorithm import algorithm
import json
import ray

# @ray.remote
@ray.remote( num_cpus=2, object_store_memory= 1000000)
class variance_x(algorithm):
    def __init__(self):
        self.config_dict_ = None
        self.config_ = None
        self.window_length_ = 10
        self.avg_ = 0
        self.var_ = 0

    def set_config(self, config):
        self.config_ = config
        self.config_dict_ = json.loads(self.config_)
        self.window_length_ = self.config_dict_["WINDOW_LENGTH"]
        self.init_flag_ = False

    def config(self):
        return self.config_

    def eval(self, value):
        if self.init_flag_ == False:
            self.init_flag_ = True
            self.avg_ = value
            self.var_ = 0
        else:
            present_avg_ = self.avg_ * (self.window_length_ - 1)/self.window_length_ + value / self.window_length_
            self.var_ = (self.window_length_ - 1)/self.window_length_ * self.var_ + (self.window_length_ - 1) / (self.window_length_ ** 2) * ((value - self.avg_)**2)
            self.avg_ = present_avg_
        return self.var_