Struct EventHeader

#[repr(C, align(64))]pub struct EventHeader {
    pub event_id: EventId,
    pub correlation_id: EventId,
    pub timestamp: i64,
    pub position: DagPosition,
    pub payload_size: u32,
    pub event_kind: EventKind,
    pub flags: EventFlags,
    pub random_seed: Option<u64>,
    pub causality: Option<Causality>,
    _reserved: [u8; 5],
}

Expand description

Event header with all metadata needed for processing.

This structure is 64 bytes and cache-line aligned for optimal performance. The payload is stored separately and referenced by the header.

Layout (64 bytes total, ordered by alignment to minimize padding):

event_id: 16 bytes (UUIDv7)
correlation_id: 16 bytes (UUIDv7)
timestamp: 8 bytes (microseconds since epoch)
position: 12 bytes (DagPosition)
payload_size: 4 bytes (u32)
event_kind: 2 bytes (EventKind)
flags: 1 byte (EventFlags)
_reserved: 5 bytes (padding to 64)

Fields§

§event_id: EventId

Unique event identifier (UUIDv7 for timestamp-sortable IDs)

§correlation_id: EventId

Correlation ID for tracing related events

§timestamp: i64

Timestamp in microseconds since Unix epoch

§position: DagPosition

Position in the event DAG

§payload_size: u32

Size of the payload in bytes

§event_kind: EventKind

Event kind (category + type)

§flags: EventFlags

Processing flags

§random_seed: Option<u64>

Random seed captured at emit time for deterministic replay

§causality: Option<Causality>

Optional causality context for distributed tracing.

When present, links this event to an OpenTelemetry trace via W3C Trace Context. Populated by the CausalitySpanLinker in the telemetry layer; omitted from serialization when absent.

§_reserved: [u8; 5]

Implementations§

impl EventHeader

pub fn new( event_id: EventId, correlation_id: EventId, timestamp: i64, position: DagPosition, payload_size: u32, event_kind: EventKind, flags: EventFlags, random_seed: Option<u64>, ) -> EventHeader

Create a new event header.

pub fn with_causality(self, causality: Causality) -> EventHeader

Attach a causality context to this header for distributed tracing.

pub fn requires_ack(&self) -> bool

Check if this event requires acknowledgment.

pub fn is_transactional(&self) -> bool

Check if this event is part of a transaction.

pub fn is_replay(&self) -> bool

Check if this event is a replay.

pub fn is_acknowledged(&self) -> bool

Check if this event has been acknowledged.

pub fn is_critical(&self) -> bool

Check if this event is critical.

pub fn acknowledge(&mut self)

Mark this event as acknowledged.

pub fn age_micros(&self, now_micros: i64) -> i64

Get the event age in microseconds from a reference time.

Trait Implementations§

impl Clone for EventHeader

fn clone(&self) -> EventHeader

Returns a duplicate of the value. Read more

1.0.0 · Source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more

impl Debug for EventHeader

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more

impl<'de> Deserialize<'de> for EventHeader

fn deserialize<D>( deserializer: D, ) -> Result<EventHeader, <D as Deserializer<'de>>::Error>
where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more

impl PartialEq for EventHeader

fn eq(&self, other: &EventHeader) -> bool

Tests for self and other values to be equal, and is used by ==.

1.0.0 · Source§

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for EventHeader

fn serialize<S>( &self, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
where S: Serializer,

Serialize this value into the given Serde serializer. Read more

impl ToSchema for EventHeader

fn name() -> Cow<'static, str>

Return name of the schema. Read more

fn schemas(schemas: &mut Vec<(String, RefOr<Schema>)>)

Implement reference [utoipa::openapi::schema::Schema]s for this type. Read more

impl Eq for EventHeader

impl StructuralPartialEq for EventHeader

Auto Trait Implementations§

impl Freeze for EventHeader

impl RefUnwindSafe for EventHeader

impl Send for EventHeader

impl Sync for EventHeader

impl Unpin for EventHeader

impl UnwindSafe for EventHeader

Blanket Implementations§

impl<T> Any for T
where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

impl<T> Borrow<T> for T
where T: ?Sized,

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for T
where T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

impl<T> CloneToUninit for T
where T: Clone,

unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)

Performs copy-assignment from self to dest. Read more

impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

fn equivalent(&self, key: &K) -> bool

Compare self to key and return true if they are equal.

impl<T> From<T> for T

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> Instrument for T

fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided [Span], returning an Instrumented wrapper. Read more

fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

impl<T, U> Into<U> for T
where U: From<T>,

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

impl<T> PartialSchema for T
where T: ComposeSchema + ?Sized,

fn schema() -> RefOr<Schema>

Return ref or schema of implementing type that can then be used to construct combined schemas.

impl<T> PolicyExt for T
where T: ?Sized,

fn and<P, B, E>(self, other: P) -> And<T, P>
where T: Policy<B, E>, P: Policy<B, E>,

Create a new Policy that returns [Action::Follow] only if self and other return Action::Follow. Read more

fn or<P, B, E>(self, other: P) -> Or<T, P>
where T: Policy<B, E>, P: Policy<B, E>,

Create a new Policy that returns [Action::Follow] if either self or other returns Action::Follow. Read more

impl<T> Same for T

type Output = T

Should always be Self

impl<T> ToOwned for T
where T: Clone,

type Owned = T

The resulting type after obtaining ownership.

fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more

impl<T, U> TryFrom<U> for T
where U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

impl<T> WithSubscriber for T

fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a [WithDispatch] wrapper. Read more

fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a [WithDispatch] wrapper. Read more

impl<T> DeserializeOwned for T
where T: for<'de> Deserialize<'de>,