mysos/executor/backup.py

from abc import abstractmethod

from twitter.common.lang import Interface


class BackupInfo(object):
  def __init__(self, backup_file, cold_backup):
    self.backup_file = backup_file
    self.cold_backup = cold_backup


class BackupStore(Interface):
  """
    The storage for Mysos executor state backup (i.e. MySQL data, etc.).

    Thread-safety: The BackupStore implementation is not expected to be thread-safe and the caller
                   should be responsible for it.
  """

  class Error(Exception): pass
  class BackupNotFoundError(Error): pass

  @abstractmethod
  def restore(self):
    """
      Restore the backup.

      :return: The BackupInfo object. None if no state is restored.
    """
    pass


class BackupStoreProvider(Interface):
  @abstractmethod
  def from_task(self, task, sandbox):
    """
      Factory method that creates a BackupStore instance from 'task' (TaskInfo).

      :return: The BackupStore instance.
    """
    pass


class NoopBackupStore(BackupStore):
  """Used when no restore is requested."""

  def restore(self):
    return None  # Returning 'None' because no state is restored.


class NoopBackupStoreProvider(BackupStoreProvider):
  """Used when no restore is requested."""

  def from_task(self, task, sandbox):
    return NoopBackupStore()