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package otgrpc
import (
"github.com/opentracing/opentracing-go"
"github.com/opentracing/opentracing-go/ext"
"github.com/opentracing/opentracing-go/log"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
)
// OpenTracingServerInterceptor returns a grpc.UnaryServerInterceptor suitable
// for use in a grpc.NewServer call.
//
// For example:
//
// s := grpc.NewServer(
// ..., // (existing ServerOptions)
// grpc.UnaryInterceptor(otgrpc.OpenTracingServerInterceptor(tracer)))
//
// All gRPC server spans will look for an OpenTracing SpanContext in the gRPC
// metadata; if found, the server span will act as the ChildOf that RPC
// SpanContext.
//
// Root or not, the server Span will be embedded in the context.Context for the
// application-specific gRPC handler(s) to access.
func OpenTracingServerInterceptor(tracer opentracing.Tracer, optFuncs ...Option) grpc.UnaryServerInterceptor {
otgrpcOpts := newOptions()
otgrpcOpts.apply(optFuncs...)
return func(
ctx context.Context,
req interface{},
info *grpc.UnaryServerInfo,
handler grpc.UnaryHandler,
) (resp interface{}, err error) {
spanContext, err := extractSpanContext(ctx, tracer)
if err != nil && err != opentracing.ErrSpanContextNotFound {
// TODO: establish some sort of error reporting mechanism here. We
// don't know where to put such an error and must rely on Tracer
// implementations to do something appropriate for the time being.
}
if otgrpcOpts.inclusionFunc != nil &&
!otgrpcOpts.inclusionFunc(spanContext, info.FullMethod, req, nil) {
return handler(ctx, req)
}
serverSpan := tracer.StartSpan(
info.FullMethod,
ext.RPCServerOption(spanContext),
gRPCComponentTag,
)
defer serverSpan.Finish()
ctx = opentracing.ContextWithSpan(ctx, serverSpan)
if otgrpcOpts.logPayloads {
serverSpan.LogFields(log.Object("gRPC request", req))
}
resp, err = handler(ctx, req)
if err == nil {
if otgrpcOpts.logPayloads {
serverSpan.LogFields(log.Object("gRPC response", resp))
}
} else {
SetSpanTags(serverSpan, err, false)
serverSpan.LogFields(log.String("event", "error"), log.String("message", err.Error()))
}
if otgrpcOpts.decorator != nil {
otgrpcOpts.decorator(serverSpan, info.FullMethod, req, resp, err)
}
return resp, err
}
}
// OpenTracingStreamServerInterceptor returns a grpc.StreamServerInterceptor suitable
// for use in a grpc.NewServer call. The interceptor instruments streaming RPCs by
// creating a single span to correspond to the lifetime of the RPC's stream.
//
// For example:
//
// s := grpc.NewServer(
// ..., // (existing ServerOptions)
// grpc.StreamInterceptor(otgrpc.OpenTracingStreamServerInterceptor(tracer)))
//
// All gRPC server spans will look for an OpenTracing SpanContext in the gRPC
// metadata; if found, the server span will act as the ChildOf that RPC
// SpanContext.
//
// Root or not, the server Span will be embedded in the context.Context for the
// application-specific gRPC handler(s) to access.
func OpenTracingStreamServerInterceptor(tracer opentracing.Tracer, optFuncs ...Option) grpc.StreamServerInterceptor {
otgrpcOpts := newOptions()
otgrpcOpts.apply(optFuncs...)
return func(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
spanContext, err := extractSpanContext(ss.Context(), tracer)
if err != nil && err != opentracing.ErrSpanContextNotFound {
// TODO: establish some sort of error reporting mechanism here. We
// don't know where to put such an error and must rely on Tracer
// implementations to do something appropriate for the time being.
}
if otgrpcOpts.inclusionFunc != nil &&
!otgrpcOpts.inclusionFunc(spanContext, info.FullMethod, nil, nil) {
return handler(srv, ss)
}
serverSpan := tracer.StartSpan(
info.FullMethod,
ext.RPCServerOption(spanContext),
gRPCComponentTag,
)
defer serverSpan.Finish()
ss = &openTracingServerStream{
ServerStream: ss,
ctx: opentracing.ContextWithSpan(ss.Context(), serverSpan),
}
err = handler(srv, ss)
if err != nil {
SetSpanTags(serverSpan, err, false)
serverSpan.LogFields(log.String("event", "error"), log.String("message", err.Error()))
}
if otgrpcOpts.decorator != nil {
otgrpcOpts.decorator(serverSpan, info.FullMethod, nil, nil, err)
}
return err
}
}
type openTracingServerStream struct {
grpc.ServerStream
ctx context.Context
}
func (ss *openTracingServerStream) Context() context.Context {
return ss.ctx
}
func extractSpanContext(ctx context.Context, tracer opentracing.Tracer) (opentracing.SpanContext, error) {
md, ok := metadata.FromIncomingContext(ctx)
if !ok {
md = metadata.New(nil)
}
return tracer.Extract(opentracing.HTTPHeaders, metadataReaderWriter{md})
}
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