Struct IndirectCauses 

pub struct IndirectCauses<M = &'static Metadata<'static>>
where
    M: Clone + Debug,
{ /* private fields */ }

The indirect (follows_from) causes of a Span.

Implementations

impl<M> IndirectCauses<M>

where M: Clone + Debug,

pub fn contains(&self, span: &Span<M>) -> bool

Returns true if the given id is among this span’s indirect causes.

use std::sync::Arc;
use tracing::{Subscriber, trace_span};
use tracing_causality::{self as causality, data::IndirectCauses};
use tracing_subscriber::{prelude::*, registry::{LookupSpan, SpanData, Registry}};

let subscriber: Arc<dyn Subscriber + Send + Sync > =
    Arc::new(Registry::default().with(causality::Layer));
subscriber.clone().init();
let subscriber: Arc<dyn Subscriber> = subscriber;
let registry = subscriber.downcast_ref::<Registry>().unwrap();

let root = trace_span!("root");
let root_id_and_metadata = causality::Span {
    id: root.id().unwrap(),
    metadata: root.metadata().unwrap()
};
let consequence = trace_span!("consequence");
let consequence_id_and_metadata = causality::Span {
    id: consequence.id().unwrap(),
    metadata: consequence.metadata().unwrap()
};
consequence.follows_from(&root_id_and_metadata.id);
consequence.follows_from(&consequence_id_and_metadata.id);

let consequence_data = registry.span_data(&consequence_id_and_metadata.id).unwrap();
let consequence_extensions = consequence_data.extensions();
let consequence_causes = consequence_extensions.get::<IndirectCauses>().unwrap();
assert!(consequence_causes.contains(&root_id_and_metadata));
assert!(consequence_causes.contains(&consequence_id_and_metadata));

pub fn iter(&self) -> impl Iterator<Item = &Span<M>>

Produces an iterator over this span’s indirect causes.

use std::sync::Arc;
use tracing::{Subscriber, trace_span};
use tracing_causality::{self as causality, data::IndirectCauses};
use tracing_subscriber::{prelude::*, registry::{LookupSpan, SpanData, Registry}};

let subscriber: Arc<dyn Subscriber + Send + Sync > =
    Arc::new(Registry::default().with(causality::Layer));
subscriber.clone().init();
let subscriber: Arc<dyn Subscriber> = subscriber;
let registry = subscriber.downcast_ref::<Registry>().unwrap();

let root = trace_span!("root");
let root_id_and_metadata = causality::Span {
    id: root.id().unwrap(),
    metadata: root.metadata().unwrap()
};
let consequence = trace_span!("consequence");
let consequence_id_and_metadata = causality::Span {
    id: consequence.id().unwrap(),
    metadata: consequence.metadata().unwrap()
};
consequence.follows_from(&root_id_and_metadata.id);

let consequence_data = registry.span_data(&consequence_id_and_metadata.id).unwrap();
let consequence_extensions = consequence_data.extensions();
let consequence_causes = consequence_extensions.get::<IndirectCauses>().unwrap();
assert_eq!(
    consequence_causes.iter().next(),
    Some(&root_id_and_metadata)
);