opentelemetry_spanprocessor_any/propagation/
text_map_propagator.rs

1//! # Text Propagator
2//!
3//! `TextMapPropagator` is a formatter to serialize and deserialize a value into a
4//! text format.
5use crate::{
6    propagation::{Extractor, Injector},
7    Context,
8};
9use std::fmt::Debug;
10use std::slice;
11
12/// Methods to inject and extract a value as text into injectors and extractors that travel
13/// in-band across process boundaries.
14pub trait TextMapPropagator: Debug {
15    /// Properly encodes the values of the current [`Context`] and injects them into
16    /// the [`Injector`].
17    ///
18    /// [`Context`]: crate::Context
19    /// [`Injector`]: crate::propagation::Injector
20    fn inject(&self, injector: &mut dyn Injector) {
21        self.inject_context(&Context::current(), injector)
22    }
23
24    /// Properly encodes the values of the [`Context`] and injects them into the
25    /// [`Injector`].
26    ///
27    /// [`Context`]: crate::Context
28    /// [`Injector`]: crate::propagation::Injector
29    fn inject_context(&self, cx: &Context, injector: &mut dyn Injector);
30
31    /// Retrieves encoded data using the provided [`Extractor`]. If no data for this
32    /// format was retrieved OR if the retrieved data is invalid, then the current
33    /// [`Context`] is returned.
34    ///
35    /// [`Context`]: crate::Context
36    /// [`Injector`]: crate::propagation::Extractor
37    fn extract(&self, extractor: &dyn Extractor) -> Context {
38        self.extract_with_context(&Context::current(), extractor)
39    }
40
41    /// Retrieves encoded data using the provided [`Extractor`]. If no data for this
42    /// format was retrieved OR if the retrieved data is invalid, then the given
43    /// [`Context`] is returned.
44    ///
45    /// [`Context`]: crate::Context
46    /// [`Injector`]: crate::propagation::Extractor
47    fn extract_with_context(&self, cx: &Context, extractor: &dyn Extractor) -> Context;
48
49    /// Returns iter of fields used by [`TextMapPropagator`]
50    ///
51    fn fields(&self) -> FieldIter<'_>;
52}
53
54/// An iterator over fields of a [`TextMapPropagator`]
55///
56#[derive(Debug)]
57pub struct FieldIter<'a>(slice::Iter<'a, String>);
58
59impl<'a> FieldIter<'a> {
60    /// Create a new `FieldIter` from a slice of propagator fields
61    pub fn new(fields: &'a [String]) -> Self {
62        FieldIter(fields.iter())
63    }
64}
65
66impl<'a> Iterator for FieldIter<'a> {
67    type Item = &'a str;
68    fn next(&mut self) -> Option<Self::Item> {
69        self.0.next().map(|field| field.as_str())
70    }
71}
opentelemetry_spanprocessor_any/propagation/text_map_propagator.rs

opentelemetry_spanprocessor_any/propagation/
text_map_propagator.rs
