opentelemetry-jaeger 0.17.0

//! Collects OpenTelemetry spans and reports them to a given Jaeger
//! `agent` or `collector` endpoint, propagate the tracing context between the applications using [Jaeger propagation format].
//!
//! See the [Jaeger Docs] for details about Jaeger and deployment information.
//!
//! *Compiler support: [requires `rustc` 1.56+][msrv]*
//!
//! [Jaeger Docs]: https://www.jaegertracing.io/docs/
//! [msrv]: #supported-rust-versions
//! [jaeger propagation format]: https://www.jaegertracing.io/docs/1.18/client-libraries/#propagation-format
//!
//! ## Quickstart
//!
//! First make sure you have a running version of the Jaeger instance
//! you want to send data to:
//!
//! ```shell
//! $ docker run -d -p6831:6831/udp -p6832:6832/udp -p16686:16686 -p14268:14268 jaegertracing/all-in-one:latest
//! ```
//!
//! Then install a new jaeger pipeline with the recommended defaults to start
//! exporting telemetry:
//!
//! ```no_run
//! use opentelemetry::trace::Tracer;
//! use opentelemetry::global;
//!
//! #[tokio::main]
//! async fn main() -> Result<(), opentelemetry::trace::TraceError> {
//!     global::set_text_map_propagator(opentelemetry_jaeger::Propagator::new());
//!     let tracer = opentelemetry_jaeger::new_agent_pipeline().install_simple()?;
//!
//!     tracer.in_span("doing_work", |cx| {
//!         // Traced app logic here...
//!     });
//!
//!     global::shutdown_tracer_provider(); // export remaining spans
//!
//!     Ok(())
//! }
//! ```
//!
//! Or if you are running on an async runtime like Tokio and want to report spans in batches
//! ```no_run
//! use opentelemetry::trace::Tracer;
//! use opentelemetry::global;
//! use opentelemetry::runtime::Tokio;
//!
//! fn main() -> Result<(), opentelemetry::trace::TraceError> {
//!     global::set_text_map_propagator(opentelemetry_jaeger::Propagator::new());
//!     let tracer = opentelemetry_jaeger::new_agent_pipeline().install_batch(Tokio)?;
//!
//!     tracer.in_span("doing_work", |cx| {
//!         // Traced app logic here...
//!     });
//!
//!     global::shutdown_tracer_provider(); // export remaining spans
//!
//!     Ok(())
//! }
//! ```
//! ## Performance
//!
//! For optimal performance, a batch exporter is recommended as the simple exporter
//! will export each span synchronously on drop. You can enable the `rt-tokio`,
//! `rt-tokio-current-thread` or `rt-async-std` features and specify a runtime
//! on the pipeline builder to have a batch exporter configured for you
//! automatically.
//!
//! ```toml
//! [dependencies]
//! opentelemetry = { version = "*", features = ["rt-tokio"] }
//! opentelemetry-jaeger = { version = "*", features = ["rt-tokio"] }
//! ```
//!
//! ```no_run
//! # fn main() -> Result<(), opentelemetry::trace::TraceError> {
//! let tracer = opentelemetry_jaeger::new_agent_pipeline()
//!     .install_batch(opentelemetry::runtime::Tokio)?;
//! # Ok(())
//! # }
//! ```
//!
//! [`tokio`]: https://tokio.rs
//! [`async-std`]: https://async.rs
//!
//! ## Jaeger Exporter From Environment Variables
//!
//! The jaeger pipeline builder can be configured dynamically via environment
//! variables. All variables are optional, a full list of accepted options can
//! be found in the [jaeger variables spec].
//!
//! [jaeger variables spec]: https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/sdk-environment-variables.md#jaeger-exporter
//!
//! ## Jaeger Collector Example
//!
//! If you want to skip the agent and submit spans directly to a Jaeger collector,
//! you can enable the optional `collector_client` feature for this crate. This
//! example expects a Jaeger collector running on `http://localhost:14268`.
//!
//! ```toml
//! [dependencies]
//! opentelemetry-jaeger = { version = "..", features = ["collector_client", "isahc_collector_client"] }
//! ```
//!
//! Then you can use the [`with_endpoint`] method to specify the endpoint:
//!
//! [`with_endpoint`]: exporter::config::collector::CollectorPipeline::with_endpoint
//!
//! ```ignore
//! // Note that this requires the `collector_client` feature.
//! // We enabled the `isahc_collector_client` feature for a default isahc http client.
//! // You can also provide your own implementation via .with_http_client() method.
//! use opentelemetry::trace::{Tracer, TraceError};
//!
//! fn main() -> Result<(), TraceError> {
//!     let tracer = opentelemetry_jaeger::new_collector_pipeline()
//!         .with_endpoint("http://localhost:14268/api/traces")
//!         // optionally set username and password for authentication of the exporter.
//!         .with_username("username")
//!         .with_password("s3cr3t")
//!         .with_isahc()
//!         //.with_http_client(<your client>) provide custom http client implementation
//!         .install_batch(opentelemetry::runtime::Tokio)?;
//!
//!     tracer.in_span("doing_work", |cx| {
//!         // Traced app logic here...
//!     });
//!
//!     Ok(())
//! }
//! ```
//! ## Resource, tags and service name
//! In order to export the spans in different format. opentelemetry uses its own
//! model internally. Most of the jaeger spans' concept can be found in this model.
//! The full list of this mapping can be found in [OpenTelemetry to Jaeger Transformation].
//!
//! The **process tags** in jaeger spans will be mapped as resource in opentelemetry. You can
//! set it through `OTEL_RESOURCE_ATTRIBUTES` environment variable or using [`with_trace_config`].
//!
//! Note that to avoid copying data multiple times. Jaeger exporter will uses resource stored in [`Exporter`].
//!
//! The **tags** in jaeger spans will be mapped as attributes in opentelemetry spans. You can
//! set it through [`set_attribute`] method.
//!
//! Each jaeger span requires a **service name**. This will be mapped as a resource with `service.name` key.
//! You can set it using one of the following methods from highest priority to lowest priority.
//! 1. [`with_service_name`].
//! 2. include a `service.name` key value pairs when configure resource using [`with_trace_config`].
//! 3. set the service name as `OTEL_SERVCE_NAME` environment variable.
//! 4. set the `service.name` attributes in `OTEL_RESOURCE_ATTRIBUTES`.
//! 5. if the service name is not provided by the above method. `unknown_service` will be used.
//!
//! Based on the service name, we update/append the `service.name` process tags in jaeger spans.
//!
//! [`with_service_name`]: crate::exporter::config::agent::AgentPipeline::with_service_name
//! [`with_trace_config`]: crate::exporter::config::agent::AgentPipeline::with_trace_config
//! [`set_attribute`]: opentelemetry::trace::Span::set_attribute
//! [OpenTelemetry to Jaeger Transformation]:https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk_exporters/jaeger.md
//!
//! ## Kitchen Sink Full Configuration
//!
//! Example showing how to override all configuration options. See the
//! [`CollectorPipeline`] and [`AgentPipeline`] docs for details of each option.
//!
//! [`CollectorPipeline`]: config::collector::CollectorPipeline
//! [`AgentPipeline`]: config::agent::AgentPipeline
//!
//! ### Export to agents
//! ```no_run
//! use opentelemetry::{sdk::{trace::{self, RandomIdGenerator, Sampler}, Resource}, global, KeyValue, trace::{Tracer, TraceError}};
//!
//! fn main() -> Result<(), TraceError> {
//!     global::set_text_map_propagator(opentelemetry_jaeger::Propagator::new());
//!     let tracer = opentelemetry_jaeger::new_agent_pipeline()
//!         .with_endpoint("localhost:6831")
//!         .with_service_name("my_app")
//!         .with_max_packet_size(9_216)
//!         .with_auto_split_batch(true)
//!         .with_instrumentation_library_tags(false)
//!         .with_trace_config(
//!             trace::config()
//!                 .with_sampler(Sampler::AlwaysOn)
//!                 .with_id_generator(RandomIdGenerator::default())
//!                 .with_max_events_per_span(64)
//!                 .with_max_attributes_per_span(16)
//!                 .with_max_events_per_span(16)
//!                  // resources will translated to tags in jaeger spans
//!                 .with_resource(Resource::new(vec![KeyValue::new("key", "value"),
//!                           KeyValue::new("process_key", "process_value")])),
//!         )
//!         .install_batch(opentelemetry::runtime::Tokio)?;
//!
//!     tracer.in_span("doing_work", |cx| {
//!         // Traced app logic here...
//!     });
//!
//!     // export remaining spans. It's optional if you can accept spans loss for the last batch.
//!     global::shutdown_tracer_provider();
//!
//!     Ok(())
//! }
//! ```
//!
//! ### Export to collectors
//! Note that this example requires `collecotr_client` and `isahc_collector_client` feature.
//! ```ignore
//! use opentelemetry::{sdk::{trace::{self, RandomIdGenerator, Sampler}, Resource}, global, KeyValue, trace::{Tracer, TraceError}};
//!
//! fn main() -> Result<(), TraceError> {
//!     global::set_text_map_propagator(opentelemetry_jaeger::Propagator::new());
//!     let tracer = opentelemetry_jaeger::new_collector_pipeline()
//!         .with_endpoint("http://localhost:14250/api/trace") // set collector endpoint
//!         .with_service_name("my_app") // the name of the application
//!         .with_trace_config(
//!             trace::config()
//!                 .with_sampler(Sampler::AlwaysOn)
//!                 .with_id_generator(RandomIdGenerator::default())
//!                 .with_max_events_per_span(64)
//!                 .with_max_attributes_per_span(16)
//!                 .with_max_events_per_span(16)
//!                 // resources will translated to tags in jaeger spans
//!                 .with_resource(Resource::new(vec![KeyValue::new("key", "value"),
//!                           KeyValue::new("process_key", "process_value")])),
//!         )
//!         // we config a surf http client with 2 seconds timeout
//!         // and have basic authentication header with username=username, password=s3cr3t
//!         .with_isahc() // requires `isahc_collector_client` feature
//!         .with_username("username")
//!         .with_password("s3cr3t")
//!         .with_timeout(std::time::Duration::from_secs(2))
//!         .install_batch(opentelemetry::runtime::Tokio)?;
//!
//!     tracer.in_span("doing_work", |cx| {
//!         // Traced app logic here...
//!     });
//!
//!     // export remaining spans. It's optional if you can accept spans loss for the last batch.
//!     global::shutdown_tracer_provider();
//!
//!     Ok(())
//! }
//! ```
//!
//! # Crate Feature Flags
//!
//! The following crate feature flags are available:
//!
//! * `collector_client`: Export span data directly to a Jaeger collector. User MUST provide the http client.
//!
//! * `hyper_collector_client`: Export span data with Jaeger collector backed by a hyper default http client.
//!
//! * `surf_collector_client`: Export span data with Jaeger collector backed by a surf default http client.
//!
//! * `reqwest_collector_client`: Export span data with Jaeger collector backed by a reqwest http client.
//!
//! * `reqwest_blocking_collector_client`: Export span data with Jaeger collector backed by a reqwest blocking http client.
//!
//! * `isahc_collector_client`: Export span data with Jaeger collector backed by a isahc http client.
//!
//! * `wasm_collector_client`: Enable collector in wasm.
//!
//! Support for recording and exporting telemetry asynchronously can be added
//! via the following flags, it extends the [`opentelemetry`] feature:
//!
//! * `rt-tokio`: Enable sending UDP packets to Jaeger agent asynchronously when the tokio
//!   [`Multi-Threaded Scheduler`] is used.
//!
//! * `rt-tokio-current-thread`: Enable sending UDP packets to Jaeger agent asynchronously when the
//!   tokio [`Current-Thread Scheduler`] is used.
//!
//! * `rt-async-std`: Enable sending UDP packets to Jaeger agent asynchronously when the
//!   [`async-std`] runtime is used.
//!
//! [`Multi-Threaded Scheduler`]: https://docs.rs/tokio/latest/tokio/runtime/index.html#multi-thread-scheduler
//! [`Current-Thread Scheduler`]: https://docs.rs/tokio/latest/tokio/runtime/index.html#current-thread-scheduler
//! [`async-std`]: https://async.rs
//! [`opentelemetry`]: https://crates.io/crates/opentelemetry
//!
//! # Supported Rust Versions
//!
//! OpenTelemetry is built against the latest stable release. The minimum
//! supported version is 1.56. The current OpenTelemetry version is not
//! guaranteed to build on Rust versions earlier than the minimum supported
//! version.
//!
//! The current stable Rust compiler and the three most recent minor versions
//! before it will always be supported. For example, if the current stable
//! compiler version is 1.56, the minimum supported version will not be
//! increased past 1.46, three minor versions prior. Increasing the minimum
//! supported compiler version is not considered a semver breaking change as
//! long as doing so complies with this policy.
#![warn(
    future_incompatible,
    missing_debug_implementations,
    missing_docs,
    nonstandard_style,
    rust_2018_idioms,
    unreachable_pub,
    unused
)]
#![cfg_attr(
    docsrs,
    feature(doc_cfg, doc_auto_cfg),
    deny(rustdoc::broken_intra_doc_links)
)]
#![doc(
    html_logo_url = "https://raw.githubusercontent.com/open-telemetry/opentelemetry-rust/main/assets/logo.svg"
)]
#![cfg_attr(test, deny(warnings))]

pub use exporter::config;
#[cfg(feature = "collector_client")]
pub use exporter::config::collector::new_collector_pipeline;
#[cfg(feature = "wasm_collector_client")]
pub use exporter::config::collector::new_wasm_collector_pipeline;
pub use exporter::{
    config::agent::new_agent_pipeline, runtime::JaegerTraceRuntime, Error, Exporter, Process,
};
pub use propagator::Propagator;

mod exporter;

#[cfg(feature = "integration_test")]
#[doc(hidden)]
pub mod testing;

mod propagator {
    use opentelemetry::{
        global::{self, Error},
        propagation::{text_map_propagator::FieldIter, Extractor, Injector, TextMapPropagator},
        trace::{
            SpanContext, SpanId, TraceContextExt, TraceError, TraceFlags, TraceId, TraceState,
        },
        Context,
    };
    use std::borrow::Cow;
    use std::str::FromStr;

    const JAEGER_HEADER: &str = "uber-trace-id";
    const JAEGER_BAGGAGE_PREFIX: &str = "uberctx-";
    const DEPRECATED_PARENT_SPAN: &str = "0";

    const TRACE_FLAG_DEBUG: TraceFlags = TraceFlags::new(0x04);

    /// The Jaeger propagator propagates span contexts in [Jaeger propagation format].
    ///
    /// Cross-cutting concerns send their state to the next process using `Propagator`s,
    /// which are defined as objects used to read and write context data to and from messages
    /// exchanged by the applications. Each concern creates a set of `Propagator`s for every
    /// supported `Propagator` type.
    ///
    /// Note that jaeger header can be set in http header or encoded as url.
    ///
    /// ## Examples
    /// ```
    /// # use opentelemetry::{global, trace::{Tracer, TraceContextExt}, Context};
    /// # use opentelemetry_jaeger::Propagator as JaegerPropagator;
    /// # fn send_request() {
    /// // setup jaeger propagator
    /// global::set_text_map_propagator(JaegerPropagator::default());
    /// // You also can init propagator with custom header name
    /// // global::set_text_map_propagator(JaegerPropagator::with_custom_header("my-custom-header"));
    ///
    /// // before sending requests to downstream services.
    /// let mut headers = std::collections::HashMap::new(); // replace by http header of the outgoing request
    /// let caller_span = global::tracer("caller").start("say hello");
    /// let cx = Context::current_with_span(caller_span);
    /// global::get_text_map_propagator(|propagator| {
    ///     propagator.inject_context(&cx, &mut headers); // propagator serialize the tracing context
    /// });
    /// // Send the request..
    /// # }
    ///
    ///
    /// # fn receive_request() {
    /// // Receive the request sent above on the other service...
    /// // setup jaeger propagator
    /// global::set_text_map_propagator(JaegerPropagator::new());
    /// // You also can init propagator with custom header name
    /// // global::set_text_map_propagator(JaegerPropagator::with_custom_header("my-custom-header"));
    ///
    /// let headers = std::collections::HashMap::new(); // replace this with http header map from incoming requests.
    /// let parent_context = global::get_text_map_propagator(|propagator| {
    ///      propagator.extract(&headers)
    /// });
    ///
    /// // this span's parent span will be caller_span in send_request functions.
    /// let receiver_span = global::tracer("receiver").start_with_context("hello", &parent_context);
    /// # }
    /// ```
    ///
    ///  [jaeger propagation format]: https://www.jaegertracing.io/docs/1.18/client-libraries/#propagation-format
    #[derive(Clone, Debug)]
    pub struct Propagator {
        baggage_prefix: &'static str,
        header_name: &'static str,
        fields: [String; 1],
    }

    // Implement default using Propagator::new() to not break compatibility with previous versions
    impl Default for Propagator {
        fn default() -> Self {
            Propagator::new()
        }
    }

    impl Propagator {
        /// Create a Jaeger propagator
        pub fn new() -> Self {
            Self::with_custom_header_and_baggage(JAEGER_HEADER, JAEGER_BAGGAGE_PREFIX)
        }

        /// Create a Jaeger propagator with custom header name
        pub fn with_custom_header(custom_header_name: &'static str) -> Self {
            Self::with_custom_header_and_baggage(custom_header_name, JAEGER_BAGGAGE_PREFIX)
        }

        /// Create a Jaeger propagator with custom header name and baggage prefix
        ///
        /// NOTE: it's implicitly fallback to the default header names when the ane of provided custom_* is empty
        /// Default header-name is `uber-trace-id` and baggage-prefix is `uberctx-`
        /// The format of serialized context and baggage's stays unchanged and not depending
        /// on provided header name and prefix.
        pub fn with_custom_header_and_baggage(
            custom_header_name: &'static str,
            custom_baggage_prefix: &'static str,
        ) -> Self {
            let custom_header_name = if custom_header_name.trim().is_empty() {
                JAEGER_HEADER
            } else {
                custom_header_name
            };

            let custom_baggage_prefix = if custom_baggage_prefix.trim().is_empty() {
                JAEGER_BAGGAGE_PREFIX
            } else {
                custom_baggage_prefix
            };

            Propagator {
                baggage_prefix: custom_baggage_prefix.trim(),
                header_name: custom_header_name.trim(),
                fields: [custom_header_name.to_owned()],
            }
        }

        /// Extract span context from header value
        fn extract_span_context(&self, extractor: &dyn Extractor) -> Result<SpanContext, ()> {
            let mut header_value = Cow::from(extractor.get(self.header_name).unwrap_or(""));
            // if there is no :, it means header_value could be encoded as url, try decode first
            if !header_value.contains(':') {
                header_value = Cow::from(header_value.replace("%3A", ":"));
            }

            let parts = header_value.split_terminator(':').collect::<Vec<&str>>();
            if parts.len() != 4 {
                return Err(());
            }

            // extract trace id
            let trace_id = self.extract_trace_id(parts[0])?;
            let span_id = self.extract_span_id(parts[1])?;
            // Ignore parent span id since it's deprecated.
            let flags = self.extract_trace_flags(parts[3])?;
            let state = self.extract_trace_state(extractor)?;

            Ok(SpanContext::new(trace_id, span_id, flags, true, state))
        }

        /// Extract trace id from the header.
        fn extract_trace_id(&self, trace_id: &str) -> Result<TraceId, ()> {
            if trace_id.len() > 32 {
                return Err(());
            }

            TraceId::from_hex(trace_id).map_err(|_| ())
        }

        /// Extract span id from the header.
        fn extract_span_id(&self, span_id: &str) -> Result<SpanId, ()> {
            if span_id.len() != 16 {
                return Err(());
            }

            SpanId::from_hex(span_id).map_err(|_| ())
        }

        /// Extract flag from the header
        ///
        /// First bit control whether to sample
        /// Second bit control whether it's a debug trace
        /// Third bit is not used.
        /// Forth bit is firehose flag, which is not supported in OT now.
        fn extract_trace_flags(&self, flag: &str) -> Result<TraceFlags, ()> {
            if flag.len() > 2 {
                return Err(());
            }
            let flag = u8::from_str(flag).map_err(|_| ())?;
            if flag & 0x01 == 0x01 {
                if flag & 0x02 == 0x02 {
                    Ok(TraceFlags::SAMPLED | TRACE_FLAG_DEBUG)
                } else {
                    Ok(TraceFlags::SAMPLED)
                }
            } else {
                // Debug flag should only be set when sampled flag is set.
                // So if debug flag is set alone. We will just use not sampled flag
                Ok(TraceFlags::default())
            }
        }

        fn extract_trace_state(&self, extractor: &dyn Extractor) -> Result<TraceState, ()> {
            let baggage_keys = extractor
                .keys()
                .into_iter()
                .filter(|key| key.starts_with(self.baggage_prefix))
                .filter_map(|key| {
                    extractor
                        .get(key)
                        .map(|value| (key.to_string(), value.to_string()))
                });

            match TraceState::from_key_value(baggage_keys) {
                Ok(trace_state) => Ok(trace_state),
                Err(trace_state_err) => {
                    global::handle_error(Error::Trace(TraceError::Other(Box::new(
                        trace_state_err,
                    ))));
                    Err(()) //todo: assign an error type instead of using ()
                }
            }
        }
    }

    impl TextMapPropagator for Propagator {
        fn inject_context(&self, cx: &Context, injector: &mut dyn Injector) {
            let span = cx.span();
            let span_context = span.span_context();
            if span_context.is_valid() {
                let flag: u8 = if span_context.is_sampled() {
                    if span_context.trace_flags() & TRACE_FLAG_DEBUG == TRACE_FLAG_DEBUG {
                        0x03
                    } else {
                        0x01
                    }
                } else {
                    0x00
                };
                let header_value = format!(
                    "{:032x}:{:016x}:{:01}:{:01x}",
                    span_context.trace_id(),
                    span_context.span_id(),
                    DEPRECATED_PARENT_SPAN,
                    flag,
                );
                injector.set(self.header_name, header_value);
            }
        }

        fn extract_with_context(&self, cx: &Context, extractor: &dyn Extractor) -> Context {
            self.extract_span_context(extractor)
                .map(|sc| cx.with_remote_span_context(sc))
                .unwrap_or_else(|_| cx.clone())
        }

        fn fields(&self) -> FieldIter<'_> {
            FieldIter::new(self.fields.as_ref())
        }
    }

    #[cfg(test)]
    mod tests {
        use super::*;
        use opentelemetry::{
            propagation::{Injector, TextMapPropagator},
            testing::trace::TestSpan,
            trace::{SpanContext, SpanId, TraceContextExt, TraceFlags, TraceId, TraceState},
            Context,
        };
        use std::collections::HashMap;

        const LONG_TRACE_ID_STR: &str = "000000000000004d0000000000000016";
        const SHORT_TRACE_ID_STR: &str = "4d0000000000000016";
        const TRACE_ID: u128 = 0x0000_0000_0000_004d_0000_0000_0000_0016;
        const SPAN_ID_STR: &str = "0000000000017c29";
        const SPAN_ID: u64 = 0x0000_0000_0001_7c29;

        fn get_extract_data() -> Vec<(&'static str, &'static str, u8, SpanContext)> {
            vec![
                (
                    LONG_TRACE_ID_STR,
                    SPAN_ID_STR,
                    1,
                    SpanContext::new(
                        TraceId::from_u128(TRACE_ID),
                        SpanId::from_u64(SPAN_ID),
                        TraceFlags::SAMPLED,
                        true,
                        TraceState::default(),
                    ),
                ),
                (
                    SHORT_TRACE_ID_STR,
                    SPAN_ID_STR,
                    1,
                    SpanContext::new(
                        TraceId::from_u128(TRACE_ID),
                        SpanId::from_u64(SPAN_ID),
                        TraceFlags::SAMPLED,
                        true,
                        TraceState::default(),
                    ),
                ),
                (
                    LONG_TRACE_ID_STR,
                    SPAN_ID_STR,
                    3,
                    SpanContext::new(
                        TraceId::from_u128(TRACE_ID),
                        SpanId::from_u64(SPAN_ID),
                        TRACE_FLAG_DEBUG | TraceFlags::SAMPLED,
                        true,
                        TraceState::default(),
                    ),
                ),
                (
                    LONG_TRACE_ID_STR,
                    SPAN_ID_STR,
                    0,
                    SpanContext::new(
                        TraceId::from_u128(TRACE_ID),
                        SpanId::from_u64(SPAN_ID),
                        TraceFlags::default(),
                        true,
                        TraceState::default(),
                    ),
                ),
                (
                    "invalidtractid",
                    SPAN_ID_STR,
                    0,
                    SpanContext::empty_context(),
                ),
                (
                    LONG_TRACE_ID_STR,
                    "invalidspanID",
                    0,
                    SpanContext::empty_context(),
                ),
                (
                    LONG_TRACE_ID_STR,
                    SPAN_ID_STR,
                    120,
                    SpanContext::empty_context(),
                ),
            ]
        }

        fn get_inject_data() -> Vec<(SpanContext, String)> {
            vec![
                (
                    SpanContext::new(
                        TraceId::from_u128(TRACE_ID),
                        SpanId::from_u64(SPAN_ID),
                        TraceFlags::SAMPLED,
                        true,
                        TraceState::default(),
                    ),
                    format!("{}:{}:0:1", LONG_TRACE_ID_STR, SPAN_ID_STR),
                ),
                (
                    SpanContext::new(
                        TraceId::from_u128(TRACE_ID),
                        SpanId::from_u64(SPAN_ID),
                        TraceFlags::default(),
                        true,
                        TraceState::default(),
                    ),
                    format!("{}:{}:0:0", LONG_TRACE_ID_STR, SPAN_ID_STR),
                ),
                (
                    SpanContext::new(
                        TraceId::from_u128(TRACE_ID),
                        SpanId::from_u64(SPAN_ID),
                        TRACE_FLAG_DEBUG | TraceFlags::SAMPLED,
                        true,
                        TraceState::default(),
                    ),
                    format!("{}:{}:0:3", LONG_TRACE_ID_STR, SPAN_ID_STR),
                ),
            ]
        }

        /// Try to extract the context using the created Propagator with custom header name
        /// from the Extractor under the `context_key` key.
        fn _test_extract_with_header(construct_header: &'static str, context_key: &'static str) {
            let propagator = Propagator::with_custom_header(construct_header);
            for (trace_id, span_id, flag, expected) in get_extract_data() {
                let mut map: HashMap<String, String> = HashMap::new();
                map.set(context_key, format!("{}:{}:0:{}", trace_id, span_id, flag));
                let context = propagator.extract(&map);
                assert_eq!(context.span().span_context(), &expected);
            }
        }

        /// Try to inject the context using the created Propagator with custom header name
        /// and expect the serialized context existence under `expect_header` key.
        fn _test_inject_with_header(construct_header: &'static str, expect_header: &'static str) {
            let propagator = Propagator::with_custom_header(construct_header);
            for (span_context, header_value) in get_inject_data() {
                let mut injector = HashMap::new();
                propagator.inject_context(
                    &Context::current_with_span(TestSpan(span_context)),
                    &mut injector,
                );
                assert_eq!(injector.get(expect_header), Some(&header_value));
            }
        }

        #[test]
        fn test_extract_empty() {
            let map: HashMap<String, String> = HashMap::new();
            let propagator = Propagator::new();
            let context = propagator.extract(&map);
            assert_eq!(context.span().span_context(), &SpanContext::empty_context())
        }

        #[test]
        fn test_inject_extract_with_default() {
            let propagator = Propagator::default();
            for (span_context, header_value) in get_inject_data() {
                let mut injector = HashMap::new();
                propagator.inject_context(
                    &Context::current_with_span(TestSpan(span_context)),
                    &mut injector,
                );
                assert_eq!(injector.get(JAEGER_HEADER), Some(&header_value));
            }
            for (trace_id, span_id, flag, expected) in get_extract_data() {
                let mut map: HashMap<String, String> = HashMap::new();
                map.set(
                    JAEGER_HEADER,
                    format!("{}:{}:0:{}", trace_id, span_id, flag),
                );
                let context = propagator.extract(&map);
                assert_eq!(context.span().span_context(), &expected);
            }
        }

        #[test]
        fn test_extract_too_many_parts() {
            let mut map: HashMap<String, String> = HashMap::new();
            map.set(
                JAEGER_HEADER,
                format!("{}:{}:0:1:aa", LONG_TRACE_ID_STR, SPAN_ID_STR),
            );
            let propagator = Propagator::new();
            let context = propagator.extract(&map);
            assert_eq!(context.span().span_context(), &SpanContext::empty_context());
        }

        #[test]
        fn test_extract_invalid_flag() {
            let mut map: HashMap<String, String> = HashMap::new();
            map.set(
                JAEGER_HEADER,
                format!("{}:{}:0:aa", LONG_TRACE_ID_STR, SPAN_ID_STR),
            );
            let propagator = Propagator::new();
            let context = propagator.extract(&map);
            assert_eq!(context.span().span_context(), &SpanContext::empty_context());
        }

        #[test]
        fn test_extract_from_url() {
            let mut map: HashMap<String, String> = HashMap::new();
            map.set(
                JAEGER_HEADER,
                format!("{}%3A{}%3A0%3A1", LONG_TRACE_ID_STR, SPAN_ID_STR),
            );
            let propagator = Propagator::new();
            let context = propagator.extract(&map);
            assert_eq!(
                context.span().span_context(),
                &SpanContext::new(
                    TraceId::from_u128(TRACE_ID),
                    SpanId::from_u64(SPAN_ID),
                    TraceFlags::SAMPLED,
                    true,
                    TraceState::default(),
                )
            );
        }

        #[test]
        fn test_extract() {
            _test_extract_with_header(JAEGER_HEADER, JAEGER_HEADER)
        }

        #[test]
        fn test_inject() {
            _test_inject_with_header(JAEGER_HEADER, JAEGER_HEADER)
        }

        #[test]
        fn test_extract_with_invalid_header() {
            for construct in &["", "   "] {
                _test_extract_with_header(construct, JAEGER_HEADER)
            }
        }

        #[test]
        fn test_extract_with_valid_header() {
            for construct in &["custom-header", "custom-header   ", "   custom-header   "] {
                _test_extract_with_header(construct, "custom-header")
            }
        }

        #[test]
        fn test_inject_with_invalid_header() {
            for construct in &["", "   "] {
                _test_inject_with_header(construct, JAEGER_HEADER)
            }
        }

        #[test]
        fn test_inject_with_valid_header() {
            for construct in &["custom-header", "custom-header   ", "   custom-header   "] {
                _test_inject_with_header(construct, "custom-header")
            }
        }
    }
}