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package mocktracer
import (
"fmt"
"net/url"
"strconv"
"strings"
"github.com/opentracing/opentracing-go"
)
const mockTextMapIdsPrefix = "mockpfx-ids-"
const mockTextMapBaggagePrefix = "mockpfx-baggage-"
var emptyContext = MockSpanContext{}
// Injector is responsible for injecting SpanContext instances in a manner suitable
// for propagation via a format-specific "carrier" object. Typically the
// injection will take place across an RPC boundary, but message queues and
// other IPC mechanisms are also reasonable places to use an Injector.
type Injector interface {
// Inject takes `SpanContext` and injects it into `carrier`. The actual type
// of `carrier` depends on the `format` passed to `Tracer.Inject()`.
//
// Implementations may return opentracing.ErrInvalidCarrier or any other
// implementation-specific error if injection fails.
Inject(ctx MockSpanContext, carrier interface{}) error
}
// Extractor is responsible for extracting SpanContext instances from a
// format-specific "carrier" object. Typically the extraction will take place
// on the server side of an RPC boundary, but message queues and other IPC
// mechanisms are also reasonable places to use an Extractor.
type Extractor interface {
// Extract decodes a SpanContext instance from the given `carrier`,
// or (nil, opentracing.ErrSpanContextNotFound) if no context could
// be found in the `carrier`.
Extract(carrier interface{}) (MockSpanContext, error)
}
// TextMapPropagator implements Injector/Extractor for TextMap and HTTPHeaders formats.
type TextMapPropagator struct {
HTTPHeaders bool
}
// Inject implements the Injector interface
func (t *TextMapPropagator) Inject(spanContext MockSpanContext, carrier interface{}) error {
writer, ok := carrier.(opentracing.TextMapWriter)
if !ok {
return opentracing.ErrInvalidCarrier
}
// Ids:
writer.Set(mockTextMapIdsPrefix+"traceid", strconv.Itoa(spanContext.TraceID))
writer.Set(mockTextMapIdsPrefix+"spanid", strconv.Itoa(spanContext.SpanID))
writer.Set(mockTextMapIdsPrefix+"sampled", fmt.Sprint(spanContext.Sampled))
// Baggage:
for baggageKey, baggageVal := range spanContext.Baggage {
safeVal := baggageVal
if t.HTTPHeaders {
safeVal = url.QueryEscape(baggageVal)
}
writer.Set(mockTextMapBaggagePrefix+baggageKey, safeVal)
}
return nil
}
// Extract implements the Extractor interface
func (t *TextMapPropagator) Extract(carrier interface{}) (MockSpanContext, error) {
reader, ok := carrier.(opentracing.TextMapReader)
if !ok {
return emptyContext, opentracing.ErrInvalidCarrier
}
rval := MockSpanContext{0, 0, true, nil}
err := reader.ForeachKey(func(key, val string) error {
lowerKey := strings.ToLower(key)
switch {
case lowerKey == mockTextMapIdsPrefix+"traceid":
// Ids:
i, err := strconv.Atoi(val)
if err != nil {
return err
}
rval.TraceID = i
case lowerKey == mockTextMapIdsPrefix+"spanid":
// Ids:
i, err := strconv.Atoi(val)
if err != nil {
return err
}
rval.SpanID = i
case lowerKey == mockTextMapIdsPrefix+"sampled":
b, err := strconv.ParseBool(val)
if err != nil {
return err
}
rval.Sampled = b
case strings.HasPrefix(lowerKey, mockTextMapBaggagePrefix):
// Baggage:
if rval.Baggage == nil {
rval.Baggage = make(map[string]string)
}
safeVal := val
if t.HTTPHeaders {
// unescape errors are ignored, nothing can be done
if rawVal, err := url.QueryUnescape(val); err == nil {
safeVal = rawVal
}
}
rval.Baggage[lowerKey[len(mockTextMapBaggagePrefix):]] = safeVal
}
return nil
})
if rval.TraceID == 0 || rval.SpanID == 0 {
return emptyContext, opentracing.ErrSpanContextNotFound
}
if err != nil {
return emptyContext, err
}
return rval, nil
}
|
