content: from rest_framework import status
  from rest_framework.exceptions import APIException
  
  __all__ = (
      'AbortRequest',
      'AbortScript',
      'AbortTransaction',
      'PermissionsViolation',
      'RQWorkerNotRunningException',
  )
  
  
  class AbortTransaction(Exception):
      """
      A dummy exception used to trigger a database transaction rollback.
      """
      pass
  
  
  class AbortRequest(Exception):
      """
      Raised to cleanly abort a request (for example, by a pre_save signal receiver).
      """
      def __init__(self, message):
          self.message = message
  
  
  class AbortScript(Exception):
      """
      Raised to cleanly abort a script.
      """
      pass
  
  
  class PermissionsViolation(Exception):
      """
      Raised when an operation was prevented because it would violate the
      allowed permissions.
      """
      message = "Operation failed due to object-level permissions violation"
  
  
  class RQWorkerNotRunningException(APIException):
      """
      Indicates the temporary inability to enqueue a new task (e.g. custom script execution) because no RQ worker
      processes are currently running.
      """
      status_code = status.HTTP_503_SERVICE_UNAVAILABLE
      default_detail = 'Unable to process request: RQ worker process not running.'
      default_code = 'rq_worker_not_running'
  