examples/src/python/bolt/stateful_count_bolt.py

#!/usr/bin/env python
# -*- encoding: utf-8 -*-

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"""module for example bolt: CountBolt"""
from collections import Counter
import heronpy.api.global_metrics as global_metrics
from heronpy.api.bolt.bolt import Bolt
from heronpy.api.state.stateful_component import StatefulComponent

# pylint: disable=unused-argument
class StatefulCountBolt(Bolt, StatefulComponent):
  """CountBolt"""
  # output field declarer
  #outputs = ['word', 'count']

  # pylint: disable=attribute-defined-outside-init
  def init_state(self, stateful_state):
    self.recovered_state = stateful_state
    self.logger.info("Checkpoint Snapshot recovered : %s" % str(self.recovered_state))

  def pre_save(self, checkpoint_id):
    for (k, v) in list(self.counter.items()):
      self.recovered_state.put(k, v)
    self.logger.info("Checkpoint Snapshot %s : %s" % (checkpoint_id, str(self.recovered_state)))

  def initialize(self, config, context):
    self.logger.info("In prepare() of CountBolt")
    self.counter = Counter()
    self.total = 0

    self.logger.info("Component-specific config: \n%s" % str(config))

  def _increment(self, word, inc_by):
    self.counter[word] += inc_by
    self.total += inc_by

  def process(self, tup):
    word = tup.values[0]
    self._increment(word, 1)
    global_metrics.safe_incr('count')
    self.ack(tup)

  def process_tick(self, tup):
    pass