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//! # OpenTelemetry Global API //! //! The global API **provides applications access to their configured //! [`Provider`] instance from anywhere in the codebase**. This allows //! applications to be less coupled to the specific Open Telemetry SDK as //! well as not manually pass references to each part of the code that needs //! to create [`Span`]s. Additionally, **3rd party middleware** or **library code** //! can be written against this generic API and not constrain users to a //! specific implementation choice. //! //! ## Usage //! //! ```rust //! use opentelemetry::api::{Provider, Tracer}; //! use opentelemetry::global; //! //! fn init_tracer() { //! let provider = opentelemetry::api::NoopProvider {}; //! //! // Configure the global `Provider` singleton when your app starts //! // (there is a no-op default if this is not set by your application) //! global::set_provider(provider); //! } //! //! fn do_something_tracked() { //! // Then you can access the configured provider via `trace_provider`. //! let provider = global::trace_provider(); //! let _span = provider.get_tracer("my-component").start("span-name", None); //! } //! //! // in main or other app start //! init_tracer(); //! do_something_tracked(); //! ``` //! //! ## Implementation //! //! This module provides types for working with the Open Telemetry API in an //! abstract implementation-agnostic way through the use of [trait objects]. //! There is a **performance penalty** due to global synchronization as well //! as heap allocation and dynamic dispatch (e.g. `Box<dyn api::Span>` vs //! `sdk::Span`), but for many applications this overhead is likely either //! insignificant or unavoidable as it is in the case of 3rd party integrations //! that do not know the span type at compile time. //! //! ### Generic interface //! //! The generic interface is provided by the [`GlobalProvider`] struct which //! can be accessed anywhere via [`trace_provider`] and allows applications to //! use the [`BoxedTracer`] and [`BoxedSpan`] instances that implement //! [`Tracer`] and [`Span`]. They wrap a boxed dyn [`GenericProvider`], //! [`GenericTracer`], and [`Span`] respectively allowing the underlying //! implementation to be set at runtime. //! //! [`Provider`]: ../api/trace/provider/trait.Provider.html //! [`Tracer`]: ../api/trace/tracer/trait.Tracer.html //! [`Span`]: ../api/trace/span/trait.Span.html //! [`GenericProvider`]: trait.GenericProvider.html //! [`GenericTracer`]: trait.GenericTracer.html //! [`GlobalProvider`]: struct.GlobalProvider.html //! [`BoxedTracer`]: struct.BoxedTracer.html //! [`BoxedSpan`]: struct.BoxedSpan.html //! [`trace_provider`]: fn.trace_provider.html //! [trait objects]: https://doc.rust-lang.org/reference/types/trait-object.html#trait-objects use crate::api; use std::any::Any; use std::fmt; use std::sync::{Arc, RwLock}; use std::time::SystemTime; /// Wraps the [`BoxedTracer`]'s [`Span`] so it can be used generically by /// applications without knowing the underlying type. /// /// [`BoxedTracer`]: struct.BoxedTracer.html /// [`Span`]: ../api/trace/span/trait.Span.html #[derive(Debug)] pub struct BoxedSpan(Box<dyn api::Span>); impl api::Span for BoxedSpan { /// Records events at a specific time in the context of a given `Span`. /// /// Note that the OpenTelemetry project documents certain ["standard event names and /// keys"](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/data-semantic-conventions.md) /// which have prescribed semantic meanings. fn add_event_with_timestamp( &self, name: String, timestamp: SystemTime, attributes: Vec<api::KeyValue>, ) { self.0.add_event_with_timestamp(name, timestamp, attributes) } /// Returns the `SpanContext` for the given `Span`. fn get_context(&self) -> api::SpanContext { self.0.get_context() } /// Returns true if this `Span` is recording information like events with the `add_event` /// operation, attributes using `set_attributes`, status with `set_status`, etc. fn is_recording(&self) -> bool { self.0.is_recording() } /// Sets a single `Attribute` where the attribute properties are passed as arguments. /// /// Note that the OpenTelemetry project documents certain ["standard /// attributes"](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/data-semantic-conventions.md) /// that have prescribed semantic meanings. fn set_attribute(&self, attribute: api::KeyValue) { self.0.set_attribute(attribute) } /// Sets the status of the `Span`. If used, this will override the default `Span` /// status, which is `OK`. fn set_status(&self, code: api::StatusCode, message: String) { self.0.set_status(code, message) } /// Updates the `Span`'s name. fn update_name(&self, new_name: String) { self.0.update_name(new_name) } /// Finishes the span. fn end(&self) { self.0.end() } /// Returns self as any fn as_any(&self) -> &dyn Any { self.0.as_any() } /// Mark span as currently active /// /// This is the _synchronous_ api. If you are using futures, you /// need to use the async api via [`instrument`]. /// /// [`instrument`]: ../api/trace/futures/trait.Instrument.html#method.instrument fn mark_as_active(&self) { self.0.mark_as_active() } /// Mark span as no longer active /// /// This is the _synchronous_ api. If you are using futures, you /// need to use the async api via [`instrument`]. /// /// [`instrument`]: ../api/trace/futures/trait.Instrument.html#method.instrument fn mark_as_inactive(&self) { self.0.mark_as_inactive() } } /// Wraps the [`GlobalProvider`]'s [`Tracer`] so it can be used generically by /// applications without knowing the underlying type. /// /// [`GlobalProvider`]: struct.GlobalProvider.html /// [`Tracer`]: ../api/trace/tracer/trait.Tracer.html #[derive(Debug)] pub struct BoxedTracer(Box<dyn GenericTracer + Send + Sync>); impl api::Tracer for BoxedTracer { /// Global tracer uses `BoxedSpan`s so that it can be a global singleton, /// which is not possible if it takes generic type parameters. type Span = BoxedSpan; /// Returns a span with an inactive `SpanContext`. Used by functions that /// need to return a default span like `get_active_span` if no span is present. fn invalid(&self) -> Self::Span { BoxedSpan(self.0.invalid_boxed()) } /// Starts a new `Span`. /// /// Each span has zero or one parent spans and zero or more child spans, which /// represent causally related operations. A tree of related spans comprises a /// trace. A span is said to be a _root span_ if it does not have a parent. Each /// trace includes a single root span, which is the shared ancestor of all other /// spans in the trace. fn start(&self, name: &str, parent_span: Option<api::SpanContext>) -> Self::Span { BoxedSpan(self.0.start_boxed(name, parent_span)) } /// Creates a span builder /// /// An ergonomic way for attributes to be configured before the `Span` is started. fn span_builder(&self, name: &str) -> api::SpanBuilder { api::SpanBuilder::from_name(name.to_string()) } /// Create a span from a `SpanBuilder` fn build(&self, builder: api::SpanBuilder) -> Self::Span { BoxedSpan(self.0.build_boxed(builder)) } /// Returns the current active span. /// /// When getting the current `Span`, the `Tracer` will return a placeholder /// `Span` with an invalid `SpanContext` if there is no currently active `Span`. fn get_active_span(&self) -> Self::Span { BoxedSpan(self.0.get_active_span_boxed()) } /// Mark a given `Span` as active. fn mark_span_as_active(&self, span: &Self::Span) { self.0.mark_span_as_active_boxed(span) } /// Mark a given `Span` as inactive. fn mark_span_as_inactive(&self, span_id: api::SpanId) { self.0.mark_span_as_inactive_boxed(span_id) } /// Clone span fn clone_span(&self, span: &Self::Span) -> Self::Span { BoxedSpan(self.0.clone_span_boxed(span)) } } /// Allows a specific [`Tracer`] to be used generically by [`BoxedTracer`] /// instances by mirroring the interface and boxing the return types. /// /// [`Tracer`]: ../api/trace/tracer/trait.Tracer.html /// [`BoxedTracer`]: struct.BoxedTracer.html pub trait GenericTracer: fmt::Debug + 'static { /// Create a new invalid span for use in cases where there are no active spans. fn invalid_boxed(&self) -> Box<dyn api::Span>; /// Returns a trait object so the underlying implementation can be swapped /// out at runtime. fn start_boxed(&self, name: &str, parent: Option<api::SpanContext>) -> Box<dyn api::Span>; /// Returns a trait object so the underlying implementation can be swapped /// out at runtime. fn build_boxed(&self, builder: api::SpanBuilder) -> Box<dyn api::Span>; /// Returns the currently active span as a BoxedSpan fn get_active_span_boxed(&self) -> Box<dyn api::Span>; /// Returns the currently active span as a BoxedSpan fn mark_span_as_active_boxed(&self, span: &dyn api::Span); /// Marks the current span as inactive fn mark_span_as_inactive_boxed(&self, span_id: api::SpanId); /// Clone span fn clone_span_boxed(&self, span: &dyn api::Span) -> Box<dyn api::Span>; } impl<S, T> GenericTracer for T where S: api::Span, T: api::Tracer<Span = S>, { /// Create a new invalid span for use in cases where there are no active spans. fn invalid_boxed(&self) -> Box<dyn api::Span> { Box::new(self.invalid()) } /// Returns a trait object so the underlying implementation can be swapped /// out at runtime. fn start_boxed(&self, name: &str, parent: Option<api::SpanContext>) -> Box<dyn api::Span> { Box::new(self.start(name, parent)) } /// Returns a trait object so the underlying implementation can be swapped /// out at runtime. fn build_boxed(&self, builder: api::SpanBuilder) -> Box<dyn api::Span> { Box::new(self.build(builder)) } /// Returns the current active span. fn get_active_span_boxed(&self) -> Box<dyn api::Span> { Box::new(self.get_active_span()) } /// Mark span as active. fn mark_span_as_active_boxed(&self, some_span: &dyn api::Span) { if let Some(span) = some_span.as_any().downcast_ref::<S>() { self.mark_span_as_active(span) }; } /// Mark span as inactive. fn mark_span_as_inactive_boxed(&self, span_id: api::SpanId) { self.mark_span_as_inactive(span_id) } /// Clone span fn clone_span_boxed(&self, some_span: &dyn api::Span) -> Box<dyn api::Span> { if let Some(span) = some_span.as_any().downcast_ref::<S>() { Box::new(self.clone_span(span)) } else { self.invalid_boxed() } } } /// Allows a specific [`Provider`] to be used generically by the /// [`GlobalProvider`] by mirroring the interface and boxing the return types. /// /// [`Provider`]: ../api/trace/provider/trait.Provider.html /// [`GlobalProvider`]: struct.GlobalProvider.html pub trait GenericProvider: fmt::Debug + 'static { /// Creates a named tracer instance that is a trait object through the underlying `Provider`. fn get_tracer_boxed(&self, name: &'static str) -> Box<dyn GenericTracer + Send + Sync>; } impl<S, T, P> GenericProvider for P where S: api::Span, T: api::Tracer<Span = S> + Send + Sync, P: api::Provider<Tracer = T>, { /// Return a boxed generic tracer fn get_tracer_boxed(&self, name: &'static str) -> Box<dyn GenericTracer + Send + Sync> { Box::new(self.get_tracer(name)) } } /// Represents the globally configured [`Provider`] instance for this /// application. This allows generic tracing through the returned /// [`BoxedTracer`] instances. /// /// [`Provider`]: ../api/trace/provider/trait.Provider.html /// [`BoxedTracer`]: struct.BoxedTracer.html #[derive(Clone, Debug)] pub struct GlobalProvider { provider: Arc<dyn GenericProvider + Send + Sync>, } impl GlobalProvider { /// Create a new GlobalProvider instance from a struct that implements `Provider`. fn new<P, T, S>(provider: P) -> Self where S: api::Span, T: api::Tracer<Span = S> + Send + Sync, P: api::Provider<Tracer = T> + Send + Sync, { GlobalProvider { provider: Arc::new(provider), } } } impl api::Provider for GlobalProvider { type Tracer = BoxedTracer; /// Find or create a named tracer using the global provider. fn get_tracer(&self, name: &'static str) -> Self::Tracer { BoxedTracer(self.provider.get_tracer_boxed(name)) } } lazy_static::lazy_static! { /// The global `Tracer` singleton. static ref GLOBAL_TRACER_PROVIDER: RwLock<GlobalProvider> = RwLock::new(GlobalProvider::new(api::NoopProvider {})); } /// Returns an instance of the currently configured global [`Provider`] through /// [`GlobalProvider`]. /// /// [`Provider`]: ../api/trace/provider/trait.Provider.html /// [`GlobalProvider`]: struct.GlobalProvider.html pub fn trace_provider() -> GlobalProvider { GLOBAL_TRACER_PROVIDER .read() .expect("GLOBAL_TRACER_PROVIDER RwLock poisoned") .clone() } /// Sets the given [`Provider`] instance as the current global provider. /// /// [`Provider`]: ../api/trace/provider/trait.Provider.html pub fn set_provider<P, T, S>(new_provider: P) where S: api::Span, T: api::Tracer<Span = S> + Send + Sync, P: api::Provider<Tracer = T> + Send + Sync, { let mut global_provider = GLOBAL_TRACER_PROVIDER .write() .expect("GLOBAL_TRACER_PROVIDER RwLock poisoned"); *global_provider = GlobalProvider::new(new_provider); } /// Returns [`NoopMeter`] for now /// /// [`NoopMeter`]: ../api/trace/noop/struct.NoopMeter.html pub fn global_meter() -> crate::api::NoopMeter { crate::api::NoopMeter {} }