> ## Documentation Index
> Fetch the complete documentation index at: https://docs.prefect.io/llms.txt
> Use this file to discover all available pages before exploring further.

# automation_held_events

# `prefect.server.events.models.automation_held_events`

Held `expect` events for proactive triggers with `after`.

Events for one bucketing key can be evaluated in any order, so an `expect` event can be
evaluated before the `after` event that opens its window, or counted in one window
before a later `after` event rolls it. Every `expect`-only event is held here, and each
bucket that opens or rolls counts the held events that occurred inside its window.

## Functions

### `slot_start` <sup>[https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation\_held\_events.py#L31](https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation_held_events.py#L31)</sup>

```python theme={null}
slot_start(occurred: datetime, width: timedelta) -> datetime
```

The start of the slot that contains `occurred`, where slots are `width` wide
and aligned to the epoch

### `holds_expect_events` <sup>[https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation\_held\_events.py#L44](https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation_held_events.py#L44)</sup>

```python theme={null}
holds_expect_events(trigger: EventTrigger) -> bool
```

Whether the trigger holds its `expect`-only events for the buckets that open
later

### `acquire_bucketing_key_lock` <sup>[https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation\_held\_events.py#L51](https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation_held_events.py#L51)</sup>

```python theme={null}
acquire_bucketing_key_lock(db: PrefectDBInterface, session: AsyncSession, trigger: EventTrigger, bucketing_key: Sequence[str]) -> None
```

Acquire a transaction-scoped lock on one bucketing key of a trigger.

The lock is released when the transaction commits or rolls back.

### `is_held` <sup>[https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation\_held\_events.py#L90](https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation_held_events.py#L90)</sup>

```python theme={null}
is_held(db: PrefectDBInterface, session: AsyncSession, trigger: EventTrigger, bucketing_key: Sequence[str], event: ReceivedEvent) -> bool
```

Whether the event is already held for this trigger and key

### `hold_event` <sup>[https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation\_held\_events.py#L108](https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation_held_events.py#L108)</sup>

```python theme={null}
hold_event(db: PrefectDBInterface, session: AsyncSession, trigger: EventTrigger, bucketing_key: Sequence[str], event: ReceivedEvent) -> None
```

Hold the event for the buckets that open later, and drop held events for the
same key that are too old or that no window needs to meet its threshold

### `held_events_in_window` <sup>[https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation\_held\_events.py#L195](https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation_held_events.py#L195)</sup>

```python theme={null}
held_events_in_window(db: PrefectDBInterface, trigger: EventTrigger, bucketing_key: Sequence[str], start: datetime, end: datetime) -> sa.ScalarSelect[int]
```

A scalar subquery counting the events held for this trigger and key that
occurred in the window from `start` (inclusive) to `end` (exclusive)

### `sweep_held_events` <sup>[https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation\_held\_events.py#L216](https://github.com/PrefectHQ/prefect/blob/main/src/prefect/server/events/models/automation_held_events.py#L216)</sup>

```python theme={null}
sweep_held_events(db: PrefectDBInterface, session: AsyncSession, now: datetime) -> None
```

Delete every held event that was held more than `HELD_EXPECT_EVENTS_RETENTION`
before `now`, unless a bucket for its key has not ended by `now`