71 lines
2.3 KiB
Go
71 lines
2.3 KiB
Go
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package opentracing
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import (
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"context"
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"encoding/base64"
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"strings"
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"github.com/opentracing/opentracing-go"
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"github.com/opentracing/opentracing-go/ext"
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"google.golang.org/grpc/metadata"
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"github.com/go-kit/kit/log"
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)
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// ToGRPCRequest returns a grpc RequestFunc that injects an OpenTracing Span
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// found in `ctx` into the grpc Metadata. If no such Span can be found, the
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// RequestFunc is a noop.
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func ToGRPCRequest(tracer opentracing.Tracer, logger log.Logger) func(ctx context.Context, md *metadata.MD) context.Context {
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return func(ctx context.Context, md *metadata.MD) context.Context {
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if span := opentracing.SpanFromContext(ctx); span != nil {
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// There's nothing we can do with an error here.
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if err := tracer.Inject(span.Context(), opentracing.TextMap, metadataReaderWriter{md}); err != nil {
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logger.Log("err", err)
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}
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}
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return ctx
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}
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}
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// FromGRPCRequest returns a grpc RequestFunc that tries to join with an
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// OpenTracing trace found in `req` and starts a new Span called
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// `operationName` accordingly. If no trace could be found in `req`, the Span
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// will be a trace root. The Span is incorporated in the returned Context and
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// can be retrieved with opentracing.SpanFromContext(ctx).
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func FromGRPCRequest(tracer opentracing.Tracer, operationName string, logger log.Logger) func(ctx context.Context, md metadata.MD) context.Context {
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return func(ctx context.Context, md metadata.MD) context.Context {
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var span opentracing.Span
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wireContext, err := tracer.Extract(opentracing.TextMap, metadataReaderWriter{&md})
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if err != nil && err != opentracing.ErrSpanContextNotFound {
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logger.Log("err", err)
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}
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span = tracer.StartSpan(operationName, ext.RPCServerOption(wireContext))
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return opentracing.ContextWithSpan(ctx, span)
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}
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}
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// A type that conforms to opentracing.TextMapReader and
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// opentracing.TextMapWriter.
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type metadataReaderWriter struct {
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*metadata.MD
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}
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func (w metadataReaderWriter) Set(key, val string) {
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key = strings.ToLower(key)
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if strings.HasSuffix(key, "-bin") {
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val = string(base64.StdEncoding.EncodeToString([]byte(val)))
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}
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(*w.MD)[key] = append((*w.MD)[key], val)
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}
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func (w metadataReaderWriter) ForeachKey(handler func(key, val string) error) error {
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for k, vals := range *w.MD {
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for _, v := range vals {
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if err := handler(k, v); err != nil {
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return err
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}
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}
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}
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return nil
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}
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