snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

stats/opencensus/trace.go

@@ -0,0 +1,130 @@
+/*
+ * Copyright 2022 gRPC 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 opencensus
+
+import (
+	"context"
+	"strings"
+	"sync/atomic"
+
+	"go.opencensus.io/trace"
+	"go.opencensus.io/trace/propagation"
+
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+)
+
+// traceInfo is data used for recording traces.
+type traceInfo struct {
+	span         *trace.Span
+	countSentMsg uint32
+	countRecvMsg uint32
+}
+
+// traceTagRPC populates context with a new span, and serializes information
+// about this span into gRPC Metadata.
+func (csh *clientStatsHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo) (context.Context, *traceInfo) {
+	// TODO: get consensus on whether this method name of "s.m" is correct.
+	mn := "Attempt." + strings.ReplaceAll(removeLeadingSlash(rti.FullMethodName), "/", ".")
+	// Returned context is ignored because will populate context with data that
+	// wraps the span instead. Don't set span kind client on this attempt span
+	// to prevent backend from prepending span name with "Sent.".
+	_, span := trace.StartSpan(ctx, mn, trace.WithSampler(csh.to.TS))
+
+	tcBin := propagation.Binary(span.SpanContext())
+	return metadata.AppendToOutgoingContext(ctx, "grpc-trace-bin", string(tcBin)), &traceInfo{
+		span:         span,
+		countSentMsg: 0, // msg events scoped to scope of context, per attempt client side
+		countRecvMsg: 0,
+	}
+}
+
+// traceTagRPC populates context with new span data, with a parent based on the
+// spanContext deserialized from context passed in (wire data in gRPC metadata)
+// if present. If multiple spanContexts exist, it takes the last one.
+func (ssh *serverStatsHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo) (context.Context, *traceInfo) {
+	mn := strings.ReplaceAll(removeLeadingSlash(rti.FullMethodName), "/", ".")
+
+	var tcBin []byte
+	if tcValues := metadata.ValueFromIncomingContext(ctx, "grpc-trace-bin"); len(tcValues) > 0 {
+		tcBin = []byte(tcValues[len(tcValues)-1])
+	}
+
+	var span *trace.Span
+	if sc, ok := propagation.FromBinary(tcBin); ok {
+		// Returned context is ignored because will populate context with data
+		// that wraps the span instead.
+		_, span = trace.StartSpanWithRemoteParent(ctx, mn, sc, trace.WithSpanKind(trace.SpanKindServer), trace.WithSampler(ssh.to.TS))
+		span.AddLink(trace.Link{TraceID: sc.TraceID, SpanID: sc.SpanID, Type: trace.LinkTypeChild})
+	} else {
+		// Returned context is ignored because will populate context with data
+		// that wraps the span instead.
+		_, span = trace.StartSpan(ctx, mn, trace.WithSpanKind(trace.SpanKindServer), trace.WithSampler(ssh.to.TS))
+	}
+
+	return ctx, &traceInfo{
+		span:         span,
+		countSentMsg: 0,
+		countRecvMsg: 0,
+	}
+}
+
+// populateSpan populates span information based on stats passed in (invariants
+// of the RPC lifecycle), and also ends span which triggers the span to be
+// exported.
+func populateSpan(_ context.Context, rs stats.RPCStats, ti *traceInfo) {
+	if ti == nil || ti.span == nil {
+		// Shouldn't happen, tagRPC call comes before this function gets called
+		// which populates this information.
+		logger.Error("ctx passed into stats handler tracing event handling has no span present")
+		return
+	}
+	span := ti.span
+
+	switch rs := rs.(type) {
+	case *stats.Begin:
+		// Note: Go always added these attributes even though they are not
+		// defined by the OpenCensus gRPC spec. Thus, they are unimportant for
+		// correctness.
+		span.AddAttributes(
+			trace.BoolAttribute("Client", rs.Client),
+			trace.BoolAttribute("FailFast", rs.FailFast),
+		)
+	case *stats.PickerUpdated:
+		span.Annotate(nil, "Delayed LB pick complete")
+	case *stats.InPayload:
+		// message id - "must be calculated as two different counters starting
+		// from one for sent messages and one for received messages."
+		mi := atomic.AddUint32(&ti.countRecvMsg, 1)
+		span.AddMessageReceiveEvent(int64(mi), int64(rs.Length), int64(rs.CompressedLength))
+	case *stats.OutPayload:
+		mi := atomic.AddUint32(&ti.countSentMsg, 1)
+		span.AddMessageSendEvent(int64(mi), int64(rs.Length), int64(rs.CompressedLength))
+	case *stats.End:
+		if rs.Error != nil {
+			// "The mapping between gRPC canonical codes and OpenCensus codes
+			// can be found here", which implies 1:1 mapping to gRPC statuses
+			// (OpenCensus statuses are based off gRPC statuses and a subset).
+			s := status.Convert(rs.Error)
+			span.SetStatus(trace.Status{Code: int32(s.Code()), Message: s.Message()})
+		} else {
+			span.SetStatus(trace.Status{Code: trace.StatusCodeOK}) // could get rid of this else conditional and just leave as 0 value, but this makes it explicit
+		}
+		span.End()
+	}
+}