| // Copyright 2018, OpenCensus Authors |
| // |
| // 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. |
| |
| package trace |
| |
| import ( |
| "context" |
| "encoding/hex" |
| |
| "go.opencensus.io/exemplar" |
| ) |
| |
| func init() { |
| exemplar.RegisterAttachmentExtractor(attachSpanContext) |
| } |
| |
| func attachSpanContext(ctx context.Context, a exemplar.Attachments) exemplar.Attachments { |
| span := FromContext(ctx) |
| if span == nil { |
| return a |
| } |
| sc := span.SpanContext() |
| if !sc.IsSampled() { |
| return a |
| } |
| if a == nil { |
| a = make(exemplar.Attachments) |
| } |
| a[exemplar.KeyTraceID] = hex.EncodeToString(sc.TraceID[:]) |
| a[exemplar.KeySpanID] = hex.EncodeToString(sc.SpanID[:]) |
| return a |
| } |
