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

stats/opencensus/opencensus.go

@@ -0,0 +1,251 @@
+/*
+ * 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 implements opencensus instrumentation code for gRPC-Go
+// clients and servers.
+package opencensus
+
+import (
+	"context"
+	"strings"
+	"time"
+
+	ocstats "go.opencensus.io/stats"
+	"go.opencensus.io/tag"
+	"go.opencensus.io/trace"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+)
+
+var (
+	joinDialOptions = internal.JoinDialOptions.(func(...grpc.DialOption) grpc.DialOption)
+)
+
+// TraceOptions are the tracing options for opencensus instrumentation.
+type TraceOptions struct {
+	// TS is the Sampler used for tracing.
+	TS trace.Sampler
+	// DisableTrace determines whether traces are disabled for an OpenCensus
+	// Dial or Server option. will overwrite any global option setting.
+	DisableTrace bool
+}
+
+// DialOption returns a dial option which enables OpenCensus instrumentation
+// code for a grpc.ClientConn.
+//
+// Client applications interested in instrumenting their grpc.ClientConn should
+// pass the dial option returned from this function as the first dial option to
+// grpc.Dial().
+//
+// Using this option will always lead to instrumentation, however in order to
+// use the data an exporter must be registered with the OpenCensus trace package
+// for traces and the OpenCensus view package for metrics. Client side has
+// retries, so a Unary and Streaming Interceptor are registered to handle per
+// RPC traces/metrics, and a Stats Handler is registered to handle per RPC
+// attempt trace/metrics. These three components registered work together in
+// conjunction, and do not work standalone. It is not supported to use this
+// alongside another stats handler dial option.
+func DialOption(to TraceOptions) grpc.DialOption {
+	csh := &clientStatsHandler{to: to}
+	return joinDialOptions(grpc.WithChainUnaryInterceptor(csh.unaryInterceptor), grpc.WithChainStreamInterceptor(csh.streamInterceptor), grpc.WithStatsHandler(csh))
+}
+
+// ServerOption returns a server option which enables OpenCensus instrumentation
+// code for a grpc.Server.
+//
+// Server applications interested in instrumenting their grpc.Server should
+// pass the server option returned from this function as the first argument to
+// grpc.NewServer().
+//
+// Using this option will always lead to instrumentation, however in order to
+// use the data an exporter must be registered with the OpenCensus trace package
+// for traces and the OpenCensus view package for metrics. Server side does not
+// have retries, so a registered Stats Handler is the only option that is
+// returned. It is not supported to use this alongside another stats handler
+// server option.
+func ServerOption(to TraceOptions) grpc.ServerOption {
+	return grpc.StatsHandler(&serverStatsHandler{to: to})
+}
+
+// createCallSpan creates a call span if tracing is enabled, which will be put
+// in the context provided if created.
+func (csh *clientStatsHandler) createCallSpan(ctx context.Context, method string) (context.Context, *trace.Span) {
+	var span *trace.Span
+	if !csh.to.DisableTrace {
+		mn := strings.ReplaceAll(removeLeadingSlash(method), "/", ".")
+		ctx, span = trace.StartSpan(ctx, mn, trace.WithSampler(csh.to.TS), trace.WithSpanKind(trace.SpanKindClient))
+	}
+	return ctx, span
+}
+
+// perCallTracesAndMetrics records per call spans and metrics.
+func perCallTracesAndMetrics(err error, span *trace.Span, startTime time.Time, method string) {
+	s := status.Convert(err)
+	if span != nil {
+		span.SetStatus(trace.Status{Code: int32(s.Code()), Message: s.Message()})
+		span.End()
+	}
+	callLatency := float64(time.Since(startTime)) / float64(time.Millisecond)
+	ocstats.RecordWithOptions(context.Background(),
+		ocstats.WithTags(
+			tag.Upsert(keyClientMethod, removeLeadingSlash(method)),
+			tag.Upsert(keyClientStatus, canonicalString(s.Code())),
+		),
+		ocstats.WithMeasurements(
+			clientAPILatency.M(callLatency),
+		),
+	)
+}
+
+// unaryInterceptor handles per RPC context management. It also handles per RPC
+// tracing and stats by creating a top level call span and recording the latency
+// for the full RPC call.
+func (csh *clientStatsHandler) unaryInterceptor(ctx context.Context, method string, req, reply any, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+	startTime := time.Now()
+	ctx, span := csh.createCallSpan(ctx, method)
+	err := invoker(ctx, method, req, reply, cc, opts...)
+	perCallTracesAndMetrics(err, span, startTime, method)
+	return err
+}
+
+// streamInterceptor handles per RPC context management. It also handles per RPC
+// tracing and stats by creating a top level call span and recording the latency
+// for the full RPC call.
+func (csh *clientStatsHandler) streamInterceptor(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
+	startTime := time.Now()
+	ctx, span := csh.createCallSpan(ctx, method)
+	callback := func(err error) {
+		perCallTracesAndMetrics(err, span, startTime, method)
+	}
+	opts = append([]grpc.CallOption{grpc.OnFinish(callback)}, opts...)
+	s, err := streamer(ctx, desc, cc, method, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return s, nil
+}
+
+type rpcInfo struct {
+	mi *metricsInfo
+	ti *traceInfo
+}
+
+type rpcInfoKey struct{}
+
+func setRPCInfo(ctx context.Context, ri *rpcInfo) context.Context {
+	return context.WithValue(ctx, rpcInfoKey{}, ri)
+}
+
+// getRPCInfo returns the rpcInfo stored in the context, or nil
+// if there isn't one.
+func getRPCInfo(ctx context.Context) *rpcInfo {
+	ri, _ := ctx.Value(rpcInfoKey{}).(*rpcInfo)
+	return ri
+}
+
+// SpanContextFromContext returns the Span Context about the Span in the
+// context. Returns false if no Span in the context.
+func SpanContextFromContext(ctx context.Context) (trace.SpanContext, bool) {
+	ri, ok := ctx.Value(rpcInfoKey{}).(*rpcInfo)
+	if !ok {
+		return trace.SpanContext{}, false
+	}
+	if ri.ti == nil || ri.ti.span == nil {
+		return trace.SpanContext{}, false
+	}
+	sc := ri.ti.span.SpanContext()
+	return sc, true
+}
+
+type clientStatsHandler struct {
+	to TraceOptions
+}
+
+// TagConn exists to satisfy stats.Handler.
+func (csh *clientStatsHandler) TagConn(ctx context.Context, _ *stats.ConnTagInfo) context.Context {
+	return ctx
+}
+
+// HandleConn exists to satisfy stats.Handler.
+func (csh *clientStatsHandler) HandleConn(context.Context, stats.ConnStats) {}
+
+// TagRPC implements per RPC attempt context management.
+func (csh *clientStatsHandler) TagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	ctx, mi := csh.statsTagRPC(ctx, rti)
+	var ti *traceInfo
+	if !csh.to.DisableTrace {
+		ctx, ti = csh.traceTagRPC(ctx, rti)
+	}
+	ri := &rpcInfo{
+		mi: mi,
+		ti: ti,
+	}
+	return setRPCInfo(ctx, ri)
+}
+
+func (csh *clientStatsHandler) HandleRPC(ctx context.Context, rs stats.RPCStats) {
+	ri := getRPCInfo(ctx)
+	if ri == nil {
+		// Shouldn't happen because TagRPC populates this information.
+		return
+	}
+	recordRPCData(ctx, rs, ri.mi)
+	if !csh.to.DisableTrace {
+		populateSpan(ctx, rs, ri.ti)
+	}
+}
+
+type serverStatsHandler struct {
+	to TraceOptions
+}
+
+// TagConn exists to satisfy stats.Handler.
+func (ssh *serverStatsHandler) TagConn(ctx context.Context, _ *stats.ConnTagInfo) context.Context {
+	return ctx
+}
+
+// HandleConn exists to satisfy stats.Handler.
+func (ssh *serverStatsHandler) HandleConn(context.Context, stats.ConnStats) {}
+
+// TagRPC implements per RPC context management.
+func (ssh *serverStatsHandler) TagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	ctx, mi := ssh.statsTagRPC(ctx, rti)
+	var ti *traceInfo
+	if !ssh.to.DisableTrace {
+		ctx, ti = ssh.traceTagRPC(ctx, rti)
+	}
+	ri := &rpcInfo{
+		mi: mi,
+		ti: ti,
+	}
+	return setRPCInfo(ctx, ri)
+}
+
+// HandleRPC implements per RPC tracing and stats implementation.
+func (ssh *serverStatsHandler) HandleRPC(ctx context.Context, rs stats.RPCStats) {
+	ri := getRPCInfo(ctx)
+	if ri == nil {
+		// Shouldn't happen because TagRPC populates this information.
+		return
+	}
+	recordRPCData(ctx, rs, ri.mi)
+	if !ssh.to.DisableTrace {
+		populateSpan(ctx, rs, ri.ti)
+	}
+}