From 2eaeda0b17366be669962cd397af66d66fc546f3 Mon Sep 17 00:00:00 2001
From: Tony Chen <zhihui_chen@foxmail.com>
Date: Thu, 18 Mar 2021 10:57:05 +0800
Subject: [PATCH] remove unused (#786)

---
 examples/blog/pkg/middleware/trace.go | 109 --------------------------
 1 file changed, 109 deletions(-)
 delete mode 100644 examples/blog/pkg/middleware/trace.go

diff --git a/examples/blog/pkg/middleware/trace.go b/examples/blog/pkg/middleware/trace.go
deleted file mode 100644
index 2cbe97155..000000000
--- a/examples/blog/pkg/middleware/trace.go
+++ /dev/null
@@ -1,109 +0,0 @@
-package tracing
-
-import (
-	"context"
-	"go.opentelemetry.io/otel"
-	"go.opentelemetry.io/otel/label"
-	"go.opentelemetry.io/otel/propagation"
-	"google.golang.org/grpc/metadata"
-
-	"github.com/go-kratos/kratos/v2/middleware"
-	"github.com/go-kratos/kratos/v2/transport/grpc"
-	"github.com/go-kratos/kratos/v2/transport/http"
-
-	oteltrace "go.opentelemetry.io/otel/trace"
-)
-
-var _ propagation.TextMapCarrier = &MetadataCarrier{}
-
-// Option is tracing option.
-type Option func(*options)
-
-type options struct {
-	TracerProvider oteltrace.TracerProvider
-	Propagators    propagation.TextMapPropagator
-}
-
-func WithPropagators(propagators propagation.TextMapPropagator) Option {
-	return func(opts *options) {
-		opts.Propagators = propagators
-	}
-}
-
-func WithTracerProvider(provider oteltrace.TracerProvider) Option {
-	return func(opts *options) {
-		opts.TracerProvider = provider
-	}
-}
-
-type MetadataCarrier struct {
-	md *metadata.MD
-}
-
-func (mc MetadataCarrier) Get(key string) string {
-	values := mc.md.Get(key)
-	if len(values) == 0 {
-		return ""
-	}
-	return values[0]
-}
-
-// Set stores the key-value pair.
-func (mc MetadataCarrier) Set(key string, value string) {
-	mc.md.Set(key, value)
-}
-
-// Server returns a new server middleware for OpenTelemetry.
-func Server(opts ...Option) middleware.Middleware {
-	options := options{}
-	for _, o := range opts {
-		o(&options)
-	}
-	if options.TracerProvider == nil {
-		options.TracerProvider = otel.GetTracerProvider()
-	}
-	if options.TracerProvider == nil {
-		options.TracerProvider = otel.GetTracerProvider()
-	}
-	tracer := options.TracerProvider.Tracer(
-		"default",
-	)
-	if options.Propagators == nil {
-		options.Propagators = otel.GetTextMapPropagator()
-	}
-	return func(handler middleware.Handler) middleware.Handler {
-		return func(ctx context.Context, req interface{}) (reply interface{}, err error) {
-			var (
-				component string
-				operation string
-			)
-			if info, ok := http.FromServerContext(ctx); ok {
-				// HTTP span
-				component = "HTTP"
-				operation = info.Request.RequestURI
-				ctx = propagation.NewCompositeTextMapPropagator(options.Propagators).Extract(ctx, info.Request.Header)
-			} else if info, ok := grpc.FromServerContext(ctx); ok {
-				// gRPC span
-				component = "gRPC"
-				operation = info.FullMethod
-				if md, ok := metadata.FromIncomingContext(ctx); ok {
-					ctx = propagation.NewCompositeTextMapPropagator(options.Propagators).Extract(ctx, MetadataCarrier{md: &md})
-				}
-			}
-			ctx, span := tracer.Start(ctx,
-				operation,
-				oteltrace.WithAttributes(label.String("component", component)),
-				oteltrace.WithSpanKind(oteltrace.SpanKindServer),
-			)
-			defer span.End()
-			if reply, err = handler(ctx, req); err != nil {
-				span.RecordError(err)
-				span.SetAttributes(
-					label.String("event", "error"),
-					label.String("message", err.Error()),
-				)
-			}
-			return
-		}
-	}
-}