nstreams_core/
event.rs

1use serde::{Deserialize, Serialize};
2
3/// A monotonically increasing version assigned per namespace stream.
4pub type EventVersion = u64;
5
6/// Wire envelope for a versioned stream event (internal / typed use).
7#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
8pub struct StreamEventEnvelope<T> {
9    pub version: EventVersion,
10    pub payload: T,
11}
12
13/// Event delivered to a subscriber. Namespace is fixed per subscription so it is omitted.
14#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
15pub struct DeliveredEvent {
16    pub request_id: String,
17    pub version: EventVersion,
18    pub payload: Vec<u8>,
19}
20
21impl DeliveredEvent {
22    pub fn from_stream_event(request_id: impl Into<String>, event: &StreamEvent) -> Self {
23        Self {
24            request_id: request_id.into(),
25            version: event.version,
26            payload: event.payload.clone(),
27        }
28    }
29
30    pub fn payload_json<T: for<'de> Deserialize<'de>>(&self) -> crate::Result<T> {
31        serde_json::from_slice(&self.payload)
32            .map_err(|e| crate::Error::Serialization(e.to_string()))
33    }
34}
35
36/// Opaque serialized event stored in backends.
37#[derive(Debug, Clone, PartialEq, Eq)]
38pub struct StreamEvent {
39    pub namespace: String,
40    pub version: EventVersion,
41    pub payload: Vec<u8>,
42}
43
44impl StreamEvent {
45    pub fn envelope<T: for<'de> Deserialize<'de>>(
46        &self,
47    ) -> crate::Result<StreamEventEnvelope<T>> {
48        let payload = serde_json::from_slice(&self.payload)
49            .map_err(|e| crate::Error::Serialization(e.to_string()))?;
50        Ok(StreamEventEnvelope {
51            version: self.version,
52            payload,
53        })
54    }
55}
56
57/// Encodes and decodes typed payloads for a namespace.
58pub trait EventCodec: Send + Sync {
59    type Event: Serialize + for<'de> Deserialize<'de> + Send + Sync;
60
61    fn encode(&self, event: &Self::Event) -> crate::Result<Vec<u8>> {
62        serde_json::to_vec(event).map_err(|e| crate::Error::Serialization(e.to_string()))
63    }
64
65    fn decode(&self, bytes: &[u8]) -> crate::Result<Self::Event> {
66        serde_json::from_slice(bytes).map_err(|e| crate::Error::Serialization(e.to_string()))
67    }
68}
nstreams_core/event.rs

nstreams_core/
event.rs
