heronpy/streamlet/impl/filterbolt.py

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

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#  to you under the Apache License, Version 2.0 (the
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#    http://www.apache.org/licenses/LICENSE-2.0
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"""module for filter bolt: FilterBolt"""
from heronpy.api.state.stateful_component import StatefulComponent
from heronpy.api.bolt.bolt import Bolt
from heronpy.api.component.component_spec import GlobalStreamId
from heronpy.api.stream import Grouping

from heronpy.streamlet.streamlet import Streamlet
from heronpy.streamlet.impl.streamletboltbase import StreamletBoltBase

# pylint: disable=unused-argument
class FilterBolt(Bolt, StatefulComponent, StreamletBoltBase):
  """FilterBolt"""
  FUNCTION = 'function'

  def init_state(self, stateful_state):
    # Filter does not have any state
    pass

  def pre_save(self, checkpoint_id):
    # Filter does not have any state
    pass

  def initialize(self, config, context):
    self.logger.debug("FilterBolt's Component-specific config: \n%s" % str(config))
    self.processed = 0
    self.emitted = 0
    if FilterBolt.FUNCTION in config:
      self.filter_function = config[FilterBolt.FUNCTION]
    else:
      raise RuntimeError("FilterBolt needs to be passed filter function")

  def process(self, tup):
    if self.filter_function(tup.values[0]):
      self.emit([tup.values[0]], stream='output')
      self.emitted += 1
    self.processed += 1
    self.ack(tup)

# pylint: disable=protected-access
class FilterStreamlet(Streamlet):
  """FilterStreamlet"""
  def __init__(self, filter_function, parent):
    super(FilterStreamlet, self).__init__()
    if not callable(filter_function):
      raise RuntimeError("Filter function has to be callable")
    if not isinstance(parent, Streamlet):
      raise RuntimeError("Parent of Filter Streamlet has to be a Streamlet")
    self._parent = parent
    self._filter_function = filter_function
    self.set_num_partitions(parent.get_num_partitions())

  def _calculate_inputs(self):
    return {GlobalStreamId(self._parent.get_name(), self._parent._output) :
            Grouping.SHUFFLE}

  def _build_this(self, builder, stage_names):
    if not self.get_name():
      self.set_name(self._default_stage_name_calculator("filter", stage_names))
    if self.get_name() in stage_names:
      raise RuntimeError("Duplicate Names")
    stage_names.add(self.get_name())
    builder.add_bolt(self.get_name(), FilterBolt, par=self.get_num_partitions(),
                     inputs=self._calculate_inputs(),
                     config={FilterBolt.FUNCTION : self._filter_function})
    return True