diff --git a/CHANGELOG.md b/CHANGELOG.md index 24874f856e3..9b62be0c145 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -8,6 +8,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm ## [Unreleased] +### Changed + +- Improve `go.opentelemetry.io/otel/propagation.TraceContext`'s performance. (#4721) + ## [1.21.0/0.44.0] 2023-11-16 ### Removed diff --git a/propagation/trace_context.go b/propagation/trace_context.go index 75a8f3435a5..63e5d62221f 100644 --- a/propagation/trace_context.go +++ b/propagation/trace_context.go @@ -18,7 +18,7 @@ import ( "context" "encoding/hex" "fmt" - "regexp" + "strings" "go.opentelemetry.io/otel/trace" ) @@ -28,6 +28,7 @@ const ( maxVersion = 254 traceparentHeader = "traceparent" tracestateHeader = "tracestate" + delimiter = "-" ) // TraceContext is a propagator that supports the W3C Trace Context format @@ -41,8 +42,8 @@ const ( type TraceContext struct{} var ( - _ TextMapPropagator = TraceContext{} - traceCtxRegExp = regexp.MustCompile("^(?P[0-9a-f]{2})-(?P[a-f0-9]{32})-(?P[a-f0-9]{16})-(?P[a-f0-9]{2})(?:-.*)?$") + _ TextMapPropagator = TraceContext{} + versionPart = fmt.Sprintf("%.2X", supportedVersion) ) // Inject set tracecontext from the Context into the carrier. @@ -59,12 +60,19 @@ func (tc TraceContext) Inject(ctx context.Context, carrier TextMapCarrier) { // Clear all flags other than the trace-context supported sampling bit. flags := sc.TraceFlags() & trace.FlagsSampled - h := fmt.Sprintf("%.2x-%s-%s-%s", - supportedVersion, - sc.TraceID(), - sc.SpanID(), - flags) - carrier.Set(traceparentHeader, h) + var sb strings.Builder + sb.Grow(2 + 32 + 16 + 2 + 3) + _, _ = sb.WriteString(versionPart) + traceID := sc.TraceID() + spanID := sc.SpanID() + flagByte := [1]byte{byte(flags)} + var buf [32]byte + for _, src := range [][]byte{traceID[:], spanID[:], flagByte[:]} { + _ = sb.WriteByte(delimiter[0]) + n := hex.Encode(buf[:], src) + _, _ = sb.Write(buf[:n]) + } + carrier.Set(traceparentHeader, sb.String()) } // Extract reads tracecontext from the carrier into a returned Context. @@ -86,21 +94,8 @@ func (tc TraceContext) extract(carrier TextMapCarrier) trace.SpanContext { return trace.SpanContext{} } - matches := traceCtxRegExp.FindStringSubmatch(h) - - if len(matches) == 0 { - return trace.SpanContext{} - } - - if len(matches) < 5 { // four subgroups plus the overall match - return trace.SpanContext{} - } - - if len(matches[1]) != 2 { - return trace.SpanContext{} - } - ver, err := hex.DecodeString(matches[1]) - if err != nil { + var ver [1]byte + if !extractPart(ver[:], &h, 2) { return trace.SpanContext{} } version := int(ver[0]) @@ -108,36 +103,24 @@ func (tc TraceContext) extract(carrier TextMapCarrier) trace.SpanContext { return trace.SpanContext{} } - if version == 0 && len(matches) != 5 { // four subgroups plus the overall match - return trace.SpanContext{} - } - - if len(matches[2]) != 32 { - return trace.SpanContext{} - } - var scc trace.SpanContextConfig - - scc.TraceID, err = trace.TraceIDFromHex(matches[2][:32]) - if err != nil { + if !extractPart(scc.TraceID[:], &h, 32) { return trace.SpanContext{} } - - if len(matches[3]) != 16 { - return trace.SpanContext{} - } - scc.SpanID, err = trace.SpanIDFromHex(matches[3]) - if err != nil { + if !extractPart(scc.SpanID[:], &h, 16) { return trace.SpanContext{} } - if len(matches[4]) != 2 { + var opts [1]byte + if !extractPart(opts[:], &h, 2) { return trace.SpanContext{} } - opts, err := hex.DecodeString(matches[4]) - if err != nil || len(opts) < 1 || (version == 0 && opts[0] > 2) { + if version == 0 && (h != "" || opts[0] > 2) { + // version 0 not allow extra + // version 0 not allow other flag return trace.SpanContext{} } + // Clear all flags other than the trace-context supported sampling bit. scc.TraceFlags = trace.TraceFlags(opts[0]) & trace.FlagsSampled @@ -155,6 +138,29 @@ func (tc TraceContext) extract(carrier TextMapCarrier) trace.SpanContext { return sc } +// upperHex detect hex is upper case Unicode characters. +func upperHex(v string) bool { + for _, c := range v { + if c >= 'A' && c <= 'F' { + return true + } + } + return false +} + +func extractPart(dst []byte, h *string, n int) bool { + part, left, _ := strings.Cut(*h, delimiter) + *h = left + // hex.Decode decodes unsupported upper-case characters, so exclude explicitly. + if len(part) != n || upperHex(part) { + return false + } + if p, err := hex.Decode(dst, []byte(part)); err != nil || p != n/2 { + return false + } + return true +} + // Fields returns the keys who's values are set with Inject. func (tc TraceContext) Fields() []string { return []string{traceparentHeader, tracestateHeader}