EventHistory

EventHistory is the ordered event store owned by each EventBus as bus.event_history. Rust stores the same history inside EventBus runtime state and exposes it through EventBus history methods rather than a standalone public EventHistory type. It is the canonical history backend in each runtime and exposes ordered access, lookup (find), and retention controls.

Common fields

max_history_size: max retained events (None/null means unbounded, 0 keeps only in-flight visibility)
max_history_drop: whether to trim oldest entries when over limit
Ordered mapping keyed by event_id

Mapping interface

EventHistory behaves like an ordered mapping in Python/TypeScript; Go exposes equivalent explicit methods.

Python
TypeScript
Go
Rust

from abxbus import EventHistory

history = EventHistory(max_history_size=100, max_history_drop=True)
history[event.event_id] = event

exists = event.event_id in history
loaded = history.get(event.event_id)
count = len(history)

for event_id, item in history.items():
    print(event_id, item.event_type)

import { EventHistory } from 'abxbus'

const history = new EventHistory({ max_history_size: 100, max_history_drop: true })
history.set(event.event_id, event)

const exists = history.has(event.event_id)
const loaded = history.get(event.event_id)
const count = history.size

for (const [event_id, item] of history) {
  console.log(event_id, item.event_type)
}

maxSize := 100
history := abxbus.NewEventHistory(&maxSize, true)
history.AddEvent(event)

exists := history.Has(event.EventID)
loaded := history.GetEvent(event.EventID)
count := history.Size()

for _, item := range history.Values() {
	fmt.Println(item.EventID, item.EventType)
}

let bus = EventBus::new_with_history(Some("HistoryBus".to_string()), Some(100), true);
let event = bus.emit(SomeEvent {
    ..Default::default()
});
block_on(event.now());

let count = bus.event_history_size();
let ids = bus.event_history_ids();
let loaded = bus.runtime_payload_for_test().get(&ids[0]).cloned();

Accessor methods

All runtimes expose explicit accessors in addition to mapping methods where the language supports them.

Python
TypeScript
Go
Rust

add_event(event)
get_event(event_id)
remove_event(event_id)
has_event(event_id)
find(...)
filter(...)
trim_event_history(...)

addEvent(event)
getEvent(event_id)
removeEvent(event_id)
hasEvent(event_id)
find(...)
filter(...)
trimEventHistory(...)

AddEvent(event)
GetEvent(event_id)
RemoveEvent(event_id)
Has(event_id)
Find(...)
Filter(...)
TrimEventHistory(...)

event_history_size()
event_history_ids()
find(...)
filter(...)
max_history_size()
max_history_drop()

`find(...)`

EventHistory.find(...) supports:

event pattern ('EventType', class, or '*')
where predicate filtering
field equality filters (**event_fields in Python, options object fields in TypeScript)
past / future windows
child_of constraints

EventBus.find(...) delegates to event_history.find(...). Future waiter ownership remains on EventBus; the bus injects the callback used for future waits.

`filter(...)`

Same as find(...) but returns the list of all matching events (newest to oldest) instead of just the first match. Accepts an additional limit argument to cap the result count. find(...) is implemented as filter(..., limit=1) returning the first result or None / null.

Retention and trim methods

trim_event_history / trimEventHistory applies configured retention policy.
on_remove callbacks let the caller run cleanup side effects when history entries are removed.

Constructor options

Python
TypeScript
Go
Rust

history = EventHistory(max_history_size=100, max_history_drop=False)

const history = new EventHistory({ max_history_size: 100, max_history_drop: false })

maxSize := 100
history := abxbus.NewEventHistory(&maxSize, false)

let bus = EventBus::new_with_history(Some("HistoryBus".to_string()), Some(100), false);

Getting Started

Features

API Reference

Concurrency Control

Integrations

Further Reading

Common fields

Mapping interface

Accessor methods

`find(...)`

`filter(...)`

Retention and trim methods

Constructor options

Getting Started

Features

API Reference

Concurrency Control

Integrations

Further Reading

Documentation Index

​Common fields

​Mapping interface

​Accessor methods

​find(...)

​filter(...)

​Retention and trim methods

​Constructor options

Common fields

Mapping interface

Accessor methods

`find(...)`

`filter(...)`

Retention and trim methods

Constructor options