src/python/grpcio/grpc/framework/base/_emission.py

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"""State and behavior for handling emitted values."""

from grpc.framework.base import interfaces
from grpc.framework.base import _interfaces


class _EmissionManager(_interfaces.EmissionManager):
  """An implementation of _interfaces.EmissionManager."""

  def __init__(
      self, lock, failure_outcome, termination_manager, transmission_manager):
    """Constructor.

    Args:
      lock: The operation-wide lock.
      failure_outcome: Whichever one of interfaces.Outcome.SERVICED_FAILURE or
        interfaces.Outcome.SERVICER_FAILURE describes this object's methods
        being called inappropriately by customer code.
      termination_manager: The _interfaces.TerminationManager for the operation.
      transmission_manager: The _interfaces.TransmissionManager for the
        operation.
    """
    self._lock = lock
    self._failure_outcome = failure_outcome
    self._termination_manager = termination_manager
    self._transmission_manager = transmission_manager
    self._ingestion_manager = None
    self._expiration_manager = None

    self._emission_complete = False

  def set_ingestion_manager_and_expiration_manager(
      self, ingestion_manager, expiration_manager):
    self._ingestion_manager = ingestion_manager
    self._expiration_manager = expiration_manager

  def _abort(self):
    self._termination_manager.abort(self._failure_outcome)
    self._transmission_manager.abort(self._failure_outcome)
    self._ingestion_manager.abort()
    self._expiration_manager.abort()

  def consume(self, value):
    with self._lock:
      if self._emission_complete:
        self._abort()
      else:
        self._transmission_manager.inmit(value, False)

  def terminate(self):
    with self._lock:
      if not self._emission_complete:
        self._termination_manager.emission_complete()
        self._transmission_manager.inmit(None, True)
        self._emission_complete = True

  def consume_and_terminate(self, value):
    with self._lock:
      if self._emission_complete:
        self._abort()
      else:
        self._termination_manager.emission_complete()
        self._transmission_manager.inmit(value, True)
        self._emission_complete = True


def front_emission_manager(lock, termination_manager, transmission_manager):
  """Creates an _interfaces.EmissionManager appropriate for front-side use.

  Args:
    lock: The operation-wide lock.
    termination_manager: The _interfaces.TerminationManager for the operation.
    transmission_manager: The _interfaces.TransmissionManager for the operation.

  Returns:
    An _interfaces.EmissionManager appropriate for front-side use.
  """
  return _EmissionManager(
      lock, interfaces.Outcome.SERVICED_FAILURE, termination_manager,
      transmission_manager)


def back_emission_manager(lock, termination_manager, transmission_manager):
  """Creates an _interfaces.EmissionManager appropriate for back-side use.

  Args:
    lock: The operation-wide lock.
    termination_manager: The _interfaces.TerminationManager for the operation.
    transmission_manager: The _interfaces.TransmissionManager for the operation.

  Returns:
    An _interfaces.EmissionManager appropriate for back-side use.
  """
  return _EmissionManager(
      lock, interfaces.Outcome.SERVICER_FAILURE, termination_manager,
      transmission_manager)