Struct Metadata 

pub struct Metadata {
    pub parameters: MetadataParameters,
    /* private fields */
}

Additional data that is sent as part of output messages.

Includes a timestamp and additional user-provided parameters. The payload is a self-describing Arrow IPC stream, so the message carries no separate type descriptor.

A node receives a Metadata alongside every input. The timestamp and metadata_version are read through accessors, while parameters — the user-provided key/value pairs — is a public field read and written directly.

Examples

use dora_message::metadata::{get_integer_param, Metadata, Parameter};

let timestamp = uhlc::HLC::default().new_timestamp();
let mut metadata = Metadata::new(timestamp);

// A fresh `Metadata` carries the current wire-format version and no
// user parameters.
assert_eq!(metadata.metadata_version(), Metadata::CURRENT_VERSION);
assert!(metadata.parameters.is_empty());

// Attach a typed parameter and read it back with the matching getter.
metadata
    .parameters
    .insert("frame".to_string(), Parameter::Integer(7));
assert_eq!(get_integer_param(&metadata.parameters, "frame"), Some(7));

Fields

parameters: MetadataParameters

User-provided key/value parameters carried alongside the payload.

A BTreeMap of Parameter values keyed by name. Read the common scalar cases through the type-checked get_string_param, get_integer_param, and get_bool_param helpers rather than matching on the Parameter variant directly.

Implementations

impl Metadata

pub const CURRENT_VERSION: u16 = 2

Current metadata wire-format version, stamped on every outgoing message.

Bumped from 0 to 1 when the ArrowTypeInfo sidecar was dropped and the wire format became Arrow-IPC-only, and from 1 to 2 when the binary encoding moved from bincode to postcard (varint integers and length prefixes, so the byte layout differs even though the field order does not). A receiver can compare metadata_version against this to detect a peer speaking an incompatible format and report it clearly instead of failing with a cryptic positional-deserialization error.

pub fn new(timestamp: Timestamp) -> Self

Create metadata with the given timestamp and no user parameters.

pub fn startup_marker(timestamp: Timestamp) -> Self

Metadata for a startup route-probe marker (see STARTUP_MARKER_PARAM).

pub fn is_startup_marker(&self) -> bool

Whether this message is a startup route-probe marker rather than node data. Markers are consumed by the receiving node’s startup barrier and must never be decoded or surfaced to user code — see STARTUP_MARKER_PARAM.

pub fn startup_ack( timestamp: Timestamp, consumer_node: &str, input_id: &str, ) -> Self

Metadata for a startup route-probe ack: the consumer-side reply to a startup marker, identifying which consumer input received it (see STARTUP_ACK_PARAM).

pub fn startup_ack_identity(&self) -> Option<(&str, &str)>

Some((consumer_node, input_id)) iff this message is a well-formed startup route-probe ack — see STARTUP_ACK_PARAM. Malformed acks (missing or wrongly-typed identity parameters) return None and are ignored by producers, which keeps the affected output on the reliable daemon path instead of switching on bad evidence.

pub fn from_parameters( timestamp: Timestamp, parameters: MetadataParameters, ) -> Self

Create metadata with the given timestamp and user parameters, stamping the current wire-format version (CURRENT_VERSION).

pub fn metadata_version(&self) -> u16

The wire-format version stamped on this metadata. Compare against CURRENT_VERSION on receive to reject peers using an incompatible format.

pub fn timestamp(&self) -> Timestamp

The hybrid-logical-clock timestamp assigned when this message was sent.

pub fn open_telemetry_context(&self) -> String

The serialized OpenTelemetry propagation context carried in the open_telemetry_context parameter, or an empty string if absent.

Trait Implementations

impl Clone for Metadata

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Metadata

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Metadata

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Metadata

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for Metadata

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Metadata