forked from looplab/eventhorizon
/
context.go
67 lines (62 loc) · 2.23 KB
/
context.go
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// Copyright (c) 2020 - The Event Horizon 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 tracing
import (
"context"
"encoding/json"
"log"
eh "github.com/looplab/eventhorizon"
"github.com/opentracing/opentracing-go"
"github.com/opentracing/opentracing-go/ext"
)
// The string keys to marshal the context.
const (
tracingSpanKeyStr = "eh_tracing_span"
)
func init() {
eh.RegisterContextMarshaler(func(ctx context.Context, vals map[string]interface{}) {
if span := opentracing.SpanFromContext(ctx); span != nil {
tracer := opentracing.GlobalTracer()
carrier := opentracing.TextMapCarrier{}
if err := tracer.Inject(span.Context(), opentracing.TextMap, &carrier); err != nil {
log.Printf("eventhorizon: could not inject tracing span: %s", err)
return
}
js, err := json.Marshal(carrier)
if err != nil {
log.Printf("eventhorizon: could not marshal tracing span: %s", err)
return
}
vals[tracingSpanKeyStr] = string(js)
}
})
eh.RegisterContextUnmarshaler(func(ctx context.Context, vals map[string]interface{}) context.Context {
if js, ok := vals[tracingSpanKeyStr].(string); ok {
tracer := opentracing.GlobalTracer()
carrier := opentracing.TextMapCarrier{}
if err := json.Unmarshal([]byte(js), &carrier); err != nil {
log.Printf("eventhorizon: could not unmarshal tracing span: %s", err)
return ctx
}
parentSpanContext, err := tracer.Extract(opentracing.TextMap, carrier)
if err != nil && err != opentracing.ErrSpanContextNotFound {
log.Printf("eventhorizon: could not extract tracing span: %s", err)
return ctx
}
span := tracer.StartSpan("eventbus", ext.RPCServerOption(parentSpanContext))
ctx = opentracing.ContextWithSpan(ctx, span)
}
return ctx
})
}