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//! Utilities for working with global telemetry primitives
//!
//! ## Global Trace API
//!
//! The global trace API **provides applications access to their configured
//! [`TracerProvider`] instance from anywhere in the codebase**. This allows
//! applications to be less coupled to the specific Open Telemetry SDK while not
//! manually passing 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 in Applications
//!
//! Applications configure their tracer either by installing a trace pipeline,
//! or calling [`set_tracer_provider`].
//!
//! ```
//! # #[cfg(feature="trace")]
//! # {
//! use opentelemetry::trace::{Tracer, noop::NoopTracerProvider};
//! use opentelemetry::global;
//!
//! fn init_tracer() {
//!     // Swap this no-op provider for your tracing service of choice (jaeger, zipkin, etc)
//!     let provider = NoopTracerProvider::new();
//!
//!     // Configure the global `TracerProvider` singleton when your app starts
//!     // (there is a no-op default if this is not set by your application)
//!     let _ = global::set_tracer_provider(provider);
//! }
//!
//! fn do_something_tracked() {
//!     // Then you can get a named tracer instance anywhere in your codebase.
//!     let tracer = global::tracer("my-component");
//!
//!     tracer.in_span("doing_work", |cx| {
//!         // Traced app logic here...
//!     });
//! }
//!
//! // in main or other app start
//! init_tracer();
//! do_something_tracked();
//! # }
//! ```
//!
//! ### Usage in Libraries
//!
//! ```
//! # #[cfg(feature="trace")]
//! # {
//! use opentelemetry::trace::{Tracer, TracerProvider};
//! use opentelemetry::global;
//!
//! pub fn my_traced_library_function() {
//!     // End users of your library will configure their global tracer provider
//!     // so you can use the global tracer without any setup
//!     let tracer = global::tracer_provider().tracer_builder("my-library-name").
//!         with_version(env!("CARGO_PKG_VERSION")).
//!         with_schema_url("https://opentelemetry.io/schemas/1.17.0").
//!         build();
//!
//!     tracer.in_span("doing_library_work", |cx| {
//!         // Traced library logic here...
//!     });
//! }
//! # }
//! ```
//!
//! [`TracerProvider`]: crate::trace::TracerProvider
//! [`Span`]: crate::trace::Span
//!
//! ## Global Metrics API
//!
//! The global metrics API **provides applications access to their configured
//! [`MeterProvider`] instance from anywhere in the codebase**. This allows
//! applications to be less coupled to the specific Open Telemetry SDK while not
//! manually passing references to each part of the code that needs to create
//! metric instruments. Additionally, **3rd party middleware** or **library code** can be
//! written against this generic API and not constrain users to a specific
//! implementation choice.
//!
//! ### Usage in Applications and libraries
//!
//! Applications and libraries can obtain meter from the global meter provider,
//! and use the meter to create instruments to emit measurements.
//!
//! ```
//! # #[cfg(feature="metrics")]
//! # {
//! use opentelemetry::metrics::{Meter};
//! use opentelemetry::{global, KeyValue};
//!
//!    fn do_something_instrumented() {
//!     let meter = global::meter("my-component");
//!     // It is recommended to reuse the same counter instance for the
//!     // lifetime of the application
//!     let counter = meter.u64_counter("my_counter").init();
//!
//!     // record measurements
//!     counter.add(1, &[KeyValue::new("mykey", "myvalue")]);
//!     }
//! }
//! ```
//!
//! ### Usage in Applications
//! Application owners have the responsibility to set the global meter provider.
//! The global meter provider can be set using the [`set_meter_provider`] function.
//! As set_meter_provider takes ownership of the provider, it is recommended to
//! provide a clone of the provider, if the application needs to use the provider
//! later to perform operations like shutdown.
//! ```
//! # #[cfg(feature="metrics")]
//! # {
//! use opentelemetry::{global, KeyValue};
//!
//! fn main() {
//!    // Set the global meter provider
//!    // global::set_meter_provider(my_meter_provider().clone());
//! }
//! # }
//! ```
//!
//! [`MeterProvider`]: crate::metrics::MeterProvider
//! [`set_meter_provider`]: crate::global::set_meter_provider

mod error_handler;
#[cfg(feature = "metrics")]
mod metrics;
#[cfg(feature = "trace")]
mod propagation;
#[cfg(feature = "trace")]
mod trace;

pub use error_handler::{handle_error, set_error_handler, Error};
#[cfg(feature = "metrics")]
#[cfg_attr(docsrs, doc(cfg(feature = "metrics")))]
pub use metrics::*;
#[cfg(feature = "trace")]
#[cfg_attr(docsrs, doc(cfg(feature = "trace")))]
pub use propagation::*;
#[cfg(feature = "trace")]
#[cfg_attr(docsrs, doc(cfg(feature = "trace")))]
pub use trace::*;