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// Copyright 2017 Palantir Technologies, Inc. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. //! Trace contexts. use {TraceId, SpanId}; /// A `TraceContext` represents a distributed trace request. /// /// It consists of a trace ID, the ID of the parent span, the ID of the /// context's span, and flags dealing with the sampling of the span. /// /// The trace context is sent to remote services on requests. For example, /// it is included in a standard set of headers in HTTP requests. #[derive(Copy, Clone)] pub struct TraceContext { trace_id: TraceId, parent_id: Option<SpanId>, span_id: SpanId, pub(crate) sampled: Option<bool>, debug: bool, } impl TraceContext { /// Returns a builder used to construct a `TraceContext`. pub fn builder() -> Builder { Builder { parent_id: None, sampled: None, debug: false, } } /// Returns the ID of the trace associated with this context. pub fn trace_id(&self) -> TraceId { self.trace_id } /// Returns the ID of the parent of the span associated with this context. pub fn parent_id(&self) -> Option<SpanId> { self.parent_id } /// Returns the ID of the span associated with this context. pub fn span_id(&self) -> SpanId { self.span_id } /// Determines if sampling has been requested for this context. /// /// A value of `None` indicates that the service working in the context is /// responsible for determining if it should be sampled. pub fn sampled(&self) -> Option<bool> { self.sampled } /// Determines if this context is in debug mode. /// /// Debug contexts should always be sampled, regardless of the value of /// `sampled()`. pub fn debug(&self) -> bool { self.debug } } /// A builder type for `TraceContext`s. pub struct Builder { parent_id: Option<SpanId>, sampled: Option<bool>, debug: bool, } impl Builder { /// Sets the ID of the parent span of this context. /// /// Defaults to `None`. pub fn parent_id(&mut self, parent_id: SpanId) -> &mut Builder { self.parent_id = Some(parent_id); self } /// Sets the sampling request for this context. /// /// Defaults to `None`. pub fn sampled(&mut self, sampled: bool) -> &mut Builder { self.sampled = Some(sampled); self } /// Sets the debug flag for this request. /// /// Defaults to `false`. pub fn debug(&mut self, debug: bool) -> &mut Builder { self.debug = debug; self } /// Constructs a `TraceContext`. pub fn build(&self, trace_id: TraceId, span_id: SpanId) -> TraceContext { TraceContext { trace_id, parent_id: self.parent_id, span_id, sampled: if self.debug { Some(true) } else { self.sampled }, debug: self.debug, } } }