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pub(crate) use tracing_core::span::Id;
#[derive(Debug)]
struct ContextId {
id: Id,
duplicate: bool,
}
/// `SpanStack` tracks what spans are currently executing on a thread-local basis.
///
/// A "separate current span" for each thread is a semantic choice, as each span
/// can be executing in a different thread.
#[derive(Debug, Default)]
pub(crate) struct SpanStack {
stack: Vec<ContextId>,
}
impl SpanStack {
#[inline]
pub(super) fn push(&mut self, id: Id) -> bool {
let duplicate = self.stack.iter().any(|i| i.id == id);
self.stack.push(ContextId { id, duplicate });
!duplicate
}
#[inline]
pub(super) fn pop(&mut self, expected_id: &Id) -> bool {
if let Some((idx, _)) = self
.stack
.iter()
.enumerate()
.rev()
.find(|(_, ctx_id)| ctx_id.id == *expected_id)
{
let ContextId { id: _, duplicate } = self.stack.remove(idx);
return !duplicate;
}
false
}
#[inline]
pub(crate) fn iter(&self) -> impl Iterator<Item = &Id> {
self.stack
.iter()
.rev()
.filter_map(|ContextId { id, duplicate }| if !*duplicate { Some(id) } else { None })
}
#[inline]
pub(crate) fn current(&self) -> Option<&Id> {
self.iter().next()
}
}
#[cfg(test)]
mod tests {
use super::{Id, SpanStack};
#[test]
fn pop_last_span() {
let mut stack = SpanStack::default();
let id = Id::from_u64(1);
stack.push(id.clone());
assert!(stack.pop(&id));
}
#[test]
fn pop_first_span() {
let mut stack = SpanStack::default();
stack.push(Id::from_u64(1));
stack.push(Id::from_u64(2));
let id = Id::from_u64(1);
assert!(stack.pop(&id));
}
}
|
