prefect.server.events.ordering.memory

Classes

EventBeingProcessed ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L32" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Indicates that an event is currently being processed and should not be processed until it is finished. This may happen due to concurrent processing.

CausalOrdering ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L40" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Methods:

clear ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L71" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

clear(self) -> None

Clear all data for this scope.

clear_all_scopes ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L80" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

clear_all_scopes(cls) -> None

Clear all data for all scopes - useful for testing.

event_has_been_seen ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L104" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

event_has_been_seen(self, event: UUID | Event) -> bool

event_has_started_processing ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L95" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

event_has_started_processing(self, event: UUID | Event) -> bool

event_is_processing ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L188" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

event_is_processing(self, event: ReceivedEvent) -> AsyncGenerator[None, None]

Mark an event as being processed for the duration of its lifespan through the ordering system.

followers_by_id ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L149" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

followers_by_id(self, follower_ids: list[UUID]) -> list[ReceivedEvent]

Returns the events with the given IDs, in the order they occurred.

forget_event_is_processing ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L100" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

forget_event_is_processing(self, event: ReceivedEvent) -> None

forget_follower ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L124" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

forget_follower(self, follower: ReceivedEvent) -> None

Forget that this event is waiting on another event to arrive.

get_followers ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L136" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

get_followers(self, leader: ReceivedEvent) -> list[ReceivedEvent]

Returns events that were waiting on this leader event to arrive.

get_lost_followers ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L158" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

get_lost_followers(self) -> list[ReceivedEvent]

Returns events that were waiting on a leader event that never arrived.

preceding_event_confirmed ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L243" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

preceding_event_confirmed(self, handler: event_handler, event: ReceivedEvent, depth: int = 0) -> AsyncGenerator[None, None]

Events may optionally declare that they logically follow another event, so that we can preserve important event orderings in the face of unreliable delivery and ordering of messages from the queues.

This function keeps track of the ID of each event that this shard has successfully processed going back to the PRECEDING_EVENT_LOOKBACK period. If an event arrives that must follow another one, confirm that we have recently seen and processed that event before proceeding.

Args:

• handler: The function to call when an out-of-order event is ready to be processed
• event: The event to be processed. This object should include metadata indicating if and what event it follows.
• depth: The current recursion depth, used to prevent infinite recursion due to cyclic dependencies between events. Defaults to 0.

Raises EventArrivedEarly if the current event shouldn't be processed yet.

record_event_as_processing ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L87" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

record_event_as_processing(self, event: ReceivedEvent) -> bool

Record that an event is being processed, returning False if already processing.

record_event_as_seen ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L109" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

record_event_as_seen(self, event: ReceivedEvent) -> None

record_follower ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L113" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

record_follower(self, event: ReceivedEvent) -> None

Remember that this event is waiting on another event to arrive.

wait_for_leader ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/ordering/memory.py#L203" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

wait_for_leader(self, event: ReceivedEvent) -> None

Given an event, wait for its leader to be processed before proceeding, or raise EventArrivedEarly if we would wait too long in this attempt.