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from enum import Enum
from typing import Optional

from pyflink.datastream.checkpointing_mode import CheckpointingMode
from pyflink.java_gateway import get_gateway

__all__ = ['CheckpointConfig', 'ExternalizedCheckpointCleanup']


class CheckpointConfig(object):
    """
    Configuration that captures all checkpointing related settings.

    :data:`DEFAULT_MODE`:

    The default checkpoint mode: exactly once.

    :data:`DEFAULT_TIMEOUT`:

    The default timeout of a checkpoint attempt: 10 minutes.

    :data:`DEFAULT_MIN_PAUSE_BETWEEN_CHECKPOINTS`:

    The default minimum pause to be made between checkpoints: none.

    :data:`DEFAULT_MAX_CONCURRENT_CHECKPOINTS`:

    The default limit of concurrently happening checkpoints: one.
    """

    DEFAULT_MODE = CheckpointingMode.EXACTLY_ONCE

    DEFAULT_TIMEOUT = 10 * 60 * 1000

    DEFAULT_MIN_PAUSE_BETWEEN_CHECKPOINTS = 0

    DEFAULT_MAX_CONCURRENT_CHECKPOINTS = 1

    def __init__(self, j_checkpoint_config):
        self._j_checkpoint_config = j_checkpoint_config

    def is_checkpointing_enabled(self) -> bool:
        """
        Checks whether checkpointing is enabled.

        :return: True if checkpointing is enables, false otherwise.
        """
        return self._j_checkpoint_config.isCheckpointingEnabled()

    def get_checkpointing_mode(self) -> CheckpointingMode:
        """
        Gets the checkpointing mode (exactly-once vs. at-least-once).

        .. seealso:: :func:`set_checkpointing_mode`

        :return: The :class:`CheckpointingMode`.
        """
        return CheckpointingMode._from_j_checkpointing_mode(
            self._j_checkpoint_config.getCheckpointingMode())

    def set_checkpointing_mode(self, checkpointing_mode: CheckpointingMode) -> 'CheckpointConfig':
        """
        Sets the checkpointing mode (:data:`CheckpointingMode.EXACTLY_ONCE` vs.
        :data:`CheckpointingMode.AT_LEAST_ONCE`).

        Example:
        ::

            >>> config.set_checkpointing_mode(CheckpointingMode.AT_LEAST_ONCE)

        :param checkpointing_mode: The :class:`CheckpointingMode`.
        """
        self._j_checkpoint_config.setCheckpointingMode(
            CheckpointingMode._to_j_checkpointing_mode(checkpointing_mode))
        return self

    def get_checkpoint_interval(self) -> int:
        """
        Gets the interval in which checkpoints are periodically scheduled.

        This setting defines the base interval. Checkpoint triggering may be delayed by the settings
        :func:`get_max_concurrent_checkpoints` and :func:`get_min_pause_between_checkpoints`.

        :return: The checkpoint interval, in milliseconds.
        """
        return self._j_checkpoint_config.getCheckpointInterval()

    def set_checkpoint_interval(self, checkpoint_interval: int) -> 'CheckpointConfig':
        """
        Sets the interval in which checkpoints are periodically scheduled.

        This setting defines the base interval. Checkpoint triggering may be delayed by the settings
        :func:`set_max_concurrent_checkpoints` and :func:`set_min_pause_between_checkpoints`.

        :param checkpoint_interval: The checkpoint interval, in milliseconds.
        """
        self._j_checkpoint_config.setCheckpointInterval(checkpoint_interval)
        return self

    def get_checkpoint_timeout(self) -> int:
        """
        Gets the maximum time that a checkpoint may take before being discarded.

        :return: The checkpoint timeout, in milliseconds.
        """
        return self._j_checkpoint_config.getCheckpointTimeout()

    def set_checkpoint_timeout(self, checkpoint_timeout: int) -> 'CheckpointConfig':
        """
        Sets the maximum time that a checkpoint may take before being discarded.

        :param checkpoint_timeout: The checkpoint timeout, in milliseconds.
        """
        self._j_checkpoint_config.setCheckpointTimeout(checkpoint_timeout)
        return self

    def get_min_pause_between_checkpoints(self) -> int:
        """
        Gets the minimal pause between checkpointing attempts. This setting defines how soon the
        checkpoint coordinator may trigger another checkpoint after it becomes possible to trigger
        another checkpoint with respect to the maximum number of concurrent checkpoints
        (see :func:`get_max_concurrent_checkpoints`).

        :return: The minimal pause before the next checkpoint is triggered.
        """
        return self._j_checkpoint_config.getMinPauseBetweenCheckpoints()

    def set_min_pause_between_checkpoints(self,
                                          min_pause_between_checkpoints: int) -> 'CheckpointConfig':
        """
        Sets the minimal pause between checkpointing attempts. This setting defines how soon the
        checkpoint coordinator may trigger another checkpoint after it becomes possible to trigger
        another checkpoint with respect to the maximum number of concurrent checkpoints
        (see :func:`set_max_concurrent_checkpoints`).

        If the maximum number of concurrent checkpoints is set to one, this setting makes
        effectively sure that a minimum amount of time passes where no checkpoint is in progress
        at all.

        :param min_pause_between_checkpoints: The minimal pause before the next checkpoint is
                                              triggered.
        """
        self._j_checkpoint_config.setMinPauseBetweenCheckpoints(min_pause_between_checkpoints)
        return self

    def get_max_concurrent_checkpoints(self) -> int:
        """
        Gets the maximum number of checkpoint attempts that may be in progress at the same time.
        If this value is *n*, then no checkpoints will be triggered while *n* checkpoint attempts
        are currently in flight. For the next checkpoint to be triggered, one checkpoint attempt
        would need to finish or expire.

        :return: The maximum number of concurrent checkpoint attempts.
        """
        return self._j_checkpoint_config.getMaxConcurrentCheckpoints()

    def set_max_concurrent_checkpoints(self, max_concurrent_checkpoints: int) -> 'CheckpointConfig':
        """
        Sets the maximum number of checkpoint attempts that may be in progress at the same time.
        If this value is *n*, then no checkpoints will be triggered while *n* checkpoint attempts
        are currently in flight. For the next checkpoint to be triggered, one checkpoint attempt
        would need to finish or expire.

        :param max_concurrent_checkpoints: The maximum number of concurrent checkpoint attempts.
        """
        self._j_checkpoint_config.setMaxConcurrentCheckpoints(max_concurrent_checkpoints)
        return self

    def is_fail_on_checkpointing_errors(self) -> bool:
        """
        This determines the behaviour of tasks if there is an error in their local checkpointing.
        If this returns true, tasks will fail as a reaction. If this returns false, task will only
        decline the failed checkpoint.

        :return: ``True`` if failing on checkpointing errors, false otherwise.
        """
        return self._j_checkpoint_config.isFailOnCheckpointingErrors()

    def set_fail_on_checkpointing_errors(self,
                                         fail_on_checkpointing_errors: bool) -> 'CheckpointConfig':
        """
        Sets the expected behaviour for tasks in case that they encounter an error in their
        checkpointing procedure. If this is set to true, the task will fail on checkpointing error.
        If this is set to false, the task will only decline a the checkpoint and continue running.
        The default is true.

        Example:
        ::

            >>> config.set_fail_on_checkpointing_errors(False)

        :param fail_on_checkpointing_errors: ``True`` if failing on checkpointing errors,
                                             false otherwise.
        """
        self._j_checkpoint_config.setFailOnCheckpointingErrors(fail_on_checkpointing_errors)
        return self

    def enable_externalized_checkpoints(
            self,
            cleanup_mode: 'ExternalizedCheckpointCleanup') -> 'CheckpointConfig':
        """
        Enables checkpoints to be persisted externally.

        Externalized checkpoints write their meta data out to persistent storage and are **not**
        automatically cleaned up when the owning job fails or is suspended (terminating with job
        status ``FAILED`` or ``SUSPENDED``). In this case, you have to manually clean up the
        checkpoint state, both the meta data and actual program state.

        The :class:`ExternalizedCheckpointCleanup` mode defines how an externalized checkpoint
        should be cleaned up on job cancellation. If you choose to retain externalized checkpoints
        on cancellation you have you handle checkpoint clean up manually when you cancel the job as
        well (terminating with job status ``CANCELED``).

        The target directory for externalized checkpoints is configured via
        ``org.apache.flink.configuration.CheckpointingOptions#CHECKPOINTS_DIRECTORY``.

        Example:
        ::

            >>> config.enable_externalized_checkpoints(
            ...     ExternalizedCheckpointCleanup.RETAIN_ON_CANCELLATION)

        :param cleanup_mode: Externalized checkpoint cleanup behaviour, the mode could be
                             :data:`ExternalizedCheckpointCleanup.DELETE_ON_CANCELLATION` or
                             :data:`ExternalizedCheckpointCleanup.RETAIN_ON_CANCELLATION`
        """
        self._j_checkpoint_config.enableExternalizedCheckpoints(
            ExternalizedCheckpointCleanup._to_j_externalized_checkpoint_cleanup(cleanup_mode))
        return self

    def is_externalized_checkpoints_enabled(self) -> bool:
        """
        Returns whether checkpoints should be persisted externally.

        :return: ``True`` if checkpoints should be externalized, false otherwise.
        """
        return self._j_checkpoint_config.isExternalizedCheckpointsEnabled()

    def is_prefer_checkpoint_for_recovery(self) -> bool:
        """
        Returns whether a job recovery should fallback to checkpoint when there is a more recent
        savepoint.

        :return: ``True`` if a job recovery should fallback to checkpoint, false otherwise.
        """
        return self._j_checkpoint_config.isPreferCheckpointForRecovery()

    def set_prefer_checkpoint_for_recovery(
            self,
            prefer_checkpoint_for_recovery: bool) -> 'CheckpointConfig':
        """
        Sets whether a job recovery should fallback to checkpoint when there is a more recent
        savepoint.

        :param prefer_checkpoint_for_recovery: ``True`` if a job recovery should fallback to
                                               checkpoint, false otherwise.
        """
        self._j_checkpoint_config.setPreferCheckpointForRecovery(prefer_checkpoint_for_recovery)
        return self

    def get_externalized_checkpoint_cleanup(self) -> Optional['ExternalizedCheckpointCleanup']:
        """
        Returns the cleanup behaviour for externalized checkpoints.

        :return: The cleanup behaviour for externalized checkpoints or ``None`` if none is
                 configured.
        """
        cleanup_mode = self._j_checkpoint_config.getExternalizedCheckpointCleanup()
        if cleanup_mode is None:
            return None
        else:
            return ExternalizedCheckpointCleanup._from_j_externalized_checkpoint_cleanup(
                cleanup_mode)

    def is_unaligned_checkpoints_enabled(self) -> bool:
        """
        Returns whether unaligned checkpoints are enabled.

        :return: ``True`` if unaligned checkpoints are enabled.
        """
        return self._j_checkpoint_config.isUnalignedCheckpointsEnabled()

    def enable_unaligned_checkpoints(self, enabled: bool = True) -> 'CheckpointConfig':
        """
        Enables unaligned checkpoints, which greatly reduce checkpointing times under backpressure.

        Unaligned checkpoints contain data stored in buffers as part of the checkpoint state, which
        allows checkpoint barriers to overtake these buffers. Thus, the checkpoint duration becomes
        independent of the current throughput as checkpoint barriers are effectively not embedded
        into the stream of data anymore.

        Unaligned checkpoints can only be enabled if :func:`get_checkpointing_mode` is
        :data:`CheckpointingMode.EXACTLY_ONCE`.

        :param enabled: ``True`` if a checkpoints should be taken in unaligned mode.
        """
        self._j_checkpoint_config.enableUnalignedCheckpoints(enabled)
        return self

    def disable_unaligned_checkpoints(self) -> 'CheckpointConfig':
        """
        Enables unaligned checkpoints, which greatly reduce checkpointing times under backpressure
        (experimental).

        Unaligned checkpoints contain data stored in buffers as part of the checkpoint state, which
        allows checkpoint barriers to overtake these buffers. Thus, the checkpoint duration becomes
        independent of the current throughput as checkpoint barriers are effectively not embedded
        into the stream of data anymore.

        Unaligned checkpoints can only be enabled if :func:`get_checkpointing_mode` is
        :data:`CheckpointingMode.EXACTLY_ONCE`.
        """
        self.enable_unaligned_checkpoints(False)
        return self


class ExternalizedCheckpointCleanup(Enum):
    """
    Cleanup behaviour for externalized checkpoints when the job is cancelled.

    :data:`DELETE_ON_CANCELLATION`:

    Delete externalized checkpoints on job cancellation.

    All checkpoint state will be deleted when you cancel the owning
    job, both the meta data and actual program state. Therefore, you
    cannot resume from externalized checkpoints after the job has been
    cancelled.

    Note that checkpoint state is always kept if the job terminates
    with state ``FAILED``.

    :data:`RETAIN_ON_CANCELLATION`:

    Retain externalized checkpoints on job cancellation.

    All checkpoint state is kept when you cancel the owning job. You
    have to manually delete both the checkpoint meta data and actual
    program state after cancelling the job.

    Note that checkpoint state is always kept if the job terminates
    with state ``FAILED``.
    """

    DELETE_ON_CANCELLATION = 0

    RETAIN_ON_CANCELLATION = 1

    @staticmethod
    def _from_j_externalized_checkpoint_cleanup(j_cleanup_mode) \
            -> 'ExternalizedCheckpointCleanup':
        return ExternalizedCheckpointCleanup[j_cleanup_mode.name()]

    def _to_j_externalized_checkpoint_cleanup(self):
        gateway = get_gateway()
        JExternalizedCheckpointCleanup = \
            gateway.jvm.org.apache.flink.streaming.api.environment.CheckpointConfig \
            .ExternalizedCheckpointCleanup
        return getattr(JExternalizedCheckpointCleanup, self.name)