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use tonic::{
metadata::{MetadataKey, MetadataMap, MetadataValue},
Status,
};
use tracing::{warn, Span};
#[cfg(feature = "otlp")]
use opentelemetry::{global, propagation::Injector};
#[cfg(feature = "otlp")]
use opentelemetry_http::HeaderExtractor;
#[cfg(feature = "otlp")]
use tracing_opentelemetry::OpenTelemetrySpanExt;
/// Trace context propagation: associate the current span with the otlp trace of the given request,
/// if any and valid. This only sets the parent trace if the otlp feature is also enabled.
pub fn accept_trace<B>(request: http::Request<B>) -> http::Request<B> {
// we only extract and set a parent trace if otlp feature is enabled, otherwise this feature is
// an noop and we return the request as is
#[cfg(feature = "otlp")]
{
// Current context, if no or invalid data is received.
let parent_context = global::get_text_map_propagator(|propagator| {
propagator.extract(&HeaderExtractor(request.headers()))
});
Span::current().set_parent(parent_context);
}
request
}
#[cfg(feature = "otlp")]
struct MetadataInjector<'a>(&'a mut MetadataMap);
#[cfg(feature = "otlp")]
impl Injector for MetadataInjector<'_> {
fn set(&mut self, key: &str, value: String) {
match MetadataKey::from_bytes(key.as_bytes()) {
Ok(key) => match MetadataValue::try_from(&value) {
Ok(value) => {
self.0.insert(key, value);
}
Err(error) => warn!(value, error = format!("{error:#}"), "parse metadata value"),
},
Err(error) => warn!(key, error = format!("{error:#}"), "parse metadata key"),
}
}
}
/// Trace context propagation: send the trace context by injecting it into the metadata of the given
/// request. This only injects the current span if the otlp feature is also enabled.
pub fn send_trace<T>(mut request: tonic::Request<T>) -> Result<tonic::Request<T>, Status> {
#[cfg(feature = "otlp")]
{
global::get_text_map_propagator(|propagator| {
let context = Span::current().context();
propagator.inject_context(&context, &mut MetadataInjector(request.metadata_mut()))
});
}
Ok(request)
}
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