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This adds an implementation of the [Correlations API](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/correlationcontext/api.md) which is used to annotate telemetry, adding context and information to metrics, traces, and logs. It is an abstract data type represented by a set of name/value pairs describing user-defined properties. Example: ```rust let propagator = CorrelationContextPropagator::new(); // can extract from any type that impls `Carrier`, usually an HTTP header map let cx = propagator.extract(&headers); // Iterate over extracted name / value pairs for (name, value) in cx.correlation_context() { // ... } // Add new correlations let cx_with_additions = cx.with_correlations(vec![Key::new("server_id").u64(42)]); // Inject correlations into http request propagator.inject_context(&cx_with_additions, &mut headers); ``` Resolves #62
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,161 @@ | ||
| //! # OpenTelemetry Correlation Context API | ||
| //! | ||
| //! A Correlation Context is used to annotate telemetry, adding context and | ||
| //! information to metrics, traces, and logs. It is an abstract data type | ||
| //! represented by a set of name/value pairs describing user-defined properties. | ||
| //! Each name in a [`CorrelationContext`] is associated with exactly one value. | ||
| //! `CorrelationContext`s are serialized according to the editor's draft of | ||
| //! the [W3C Correlation Context] specification. | ||
| //! | ||
| //! [`CorrelationContext`]: struct.CorrelationContext.html | ||
| //! [W3C Correlation Context]: https://w3c.github.io/correlation-context/ | ||
| //! | ||
| //! # Examples | ||
| //! | ||
| //! ``` | ||
| //! use opentelemetry::api::{ | ||
| //! CorrelationContextExt, CorrelationContextPropagator, HttpTextFormat, Key | ||
| //! }; | ||
| //! use std::collections::HashMap; | ||
| //! | ||
| //! // Example correlation value passed in externally via http headers | ||
| //! let mut headers = HashMap::new(); | ||
| //! headers.insert("Correlation-Context", "user_id=1".to_string()); | ||
| //! | ||
| //! let propagator = CorrelationContextPropagator::new(); | ||
| //! // can extract from any type that impls `Carrier`, usually an HTTP header map | ||
| //! let cx = propagator.extract(&headers); | ||
| //! | ||
| //! // Iterate over extracted name / value pairs | ||
| //! for (name, value) in cx.correlation_context() { | ||
| //! // ... | ||
| //! } | ||
| //! | ||
| //! // Add new correlations | ||
| //! let cx_with_additions = cx.with_correlations(vec![Key::new("server_id").u64(42)]); | ||
| //! | ||
| //! // Inject correlations into http request | ||
| //! propagator.inject_context(&cx_with_additions, &mut headers); | ||
| //! | ||
| //! let header_value = headers.get("Correlation-Context").expect("header is injected"); | ||
| //! assert!(header_value.contains("user_id=1"), "still contains previous name / value"); | ||
| //! assert!(header_value.contains("server_id=42"), "contains new name / value pair"); | ||
| //! ``` | ||
| use crate::api; | ||
| use std::collections::{hash_map, HashMap}; | ||
| use std::iter::FromIterator; | ||
|
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| mod propagation; | ||
|
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| pub use propagation::{CorrelationContextExt, CorrelationContextPropagator}; | ||
|
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| /// A set of name/value pairs describing user-defined properties across systems. | ||
| #[derive(Debug, Default)] | ||
| pub struct CorrelationContext { | ||
| inner: HashMap<api::Key, api::Value>, | ||
| } | ||
|
|
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| impl CorrelationContext { | ||
| /// Creates an empty `CorrelationContext`. | ||
| pub fn new() -> Self { | ||
| CorrelationContext { | ||
| inner: HashMap::default(), | ||
| } | ||
| } | ||
|
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| /// Returns a reference to the value associated with a given name | ||
| /// | ||
| /// # Examples | ||
| /// | ||
| /// ``` | ||
| /// use opentelemetry::api::{CorrelationContext, Value}; | ||
| /// | ||
| /// let mut cc = CorrelationContext::new(); | ||
| /// let _ = cc.insert("my-name", "my-value"); | ||
| /// | ||
| /// assert_eq!(cc.get("my-name"), Some(&Value::String("my-value".to_string()))) | ||
| /// ``` | ||
| pub fn get<T: Into<api::Key>>(&self, key: T) -> Option<&api::Value> { | ||
| self.inner.get(&key.into()) | ||
| } | ||
|
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| /// Inserts a name-value pair into the correlation context. | ||
| /// | ||
| /// If the name was not present, [`None`] is returned. If the name was present, | ||
| /// the value is updated, and the old value is returned. | ||
| /// | ||
| /// # Examples | ||
| /// | ||
| /// ``` | ||
| /// use opentelemetry::api::{CorrelationContext, Value}; | ||
| /// | ||
| /// let mut cc = CorrelationContext::new(); | ||
| /// let _ = cc.insert("my-name", "my-value"); | ||
| /// | ||
| /// assert_eq!(cc.get("my-name"), Some(&Value::String("my-value".to_string()))) | ||
| /// ``` | ||
| pub fn insert<K, V>(&mut self, key: K, value: V) -> Option<api::Value> | ||
| where | ||
| K: Into<api::Key>, | ||
| V: Into<api::Value>, | ||
| { | ||
| self.inner.insert(key.into(), value.into()) | ||
| } | ||
|
|
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| /// Removes a name from the correlation context, returning the value | ||
| /// corresponding to the name if the pair was previously in the map. | ||
| pub fn remove<K: Into<api::Key>>(&mut self, key: K) -> Option<api::Value> { | ||
| self.inner.remove(&key.into()) | ||
| } | ||
|
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| /// Returns the number of attributes for this correlation context | ||
| pub fn len(&self) -> usize { | ||
| self.inner.len() | ||
| } | ||
|
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| /// Returns `true` if the correlation context contains no items. | ||
| pub fn is_empty(&self) -> bool { | ||
| self.inner.is_empty() | ||
| } | ||
|
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| /// Gets an iterator over the correlation context items, sorted by name. | ||
| pub fn iter(&self) -> Iter { | ||
| self.into_iter() | ||
| } | ||
| } | ||
|
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| /// An iterator over the entries of a `CorrelationContext`. | ||
| #[derive(Debug)] | ||
| pub struct Iter<'a>(hash_map::Iter<'a, api::Key, api::Value>); | ||
| impl<'a> Iterator for Iter<'a> { | ||
| type Item = (&'a api::Key, &'a api::Value); | ||
|
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| fn next(&mut self) -> Option<Self::Item> { | ||
| self.0.next() | ||
| } | ||
| } | ||
|
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| impl<'a> IntoIterator for &'a CorrelationContext { | ||
| type Item = (&'a api::Key, &'a api::Value); | ||
| type IntoIter = Iter<'a>; | ||
|
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| fn into_iter(self) -> Self::IntoIter { | ||
| Iter(self.inner.iter()) | ||
| } | ||
| } | ||
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| impl FromIterator<(api::Key, api::Value)> for CorrelationContext { | ||
| fn from_iter<I: IntoIterator<Item = (api::Key, api::Value)>>(iter: I) -> Self { | ||
| CorrelationContext { | ||
| inner: iter.into_iter().collect(), | ||
| } | ||
| } | ||
| } | ||
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| impl FromIterator<api::KeyValue> for CorrelationContext { | ||
| fn from_iter<I: IntoIterator<Item = api::KeyValue>>(iter: I) -> Self { | ||
| CorrelationContext { | ||
| inner: iter.into_iter().map(|kv| (kv.key, kv.value)).collect(), | ||
| } | ||
| } | ||
| } |
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