text: // Unless explicitly stated otherwise all files in this repository are licensed
  // under the Apache License Version 2.0.
  // This product includes software developed at Datadog (https://www.datadoghq.com/).
  // Copyright 2016-2020 Datadog, Inc.
  
  // Package gin provides functions to trace the gin-gonic/gin package (https://github.com/gin-gonic/gin).
  package gin // import "gopkg.in/DataDog/dd-trace-go.v1/contrib/gin-gonic/gin"
  
  import (
  	"fmt"
  	"math"
  	"net/http"
  	"strconv"
  
  	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
  	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
  	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
  
  	"github.com/gin-gonic/gin"
  )
  
  // Middleware returns middleware that will trace incoming requests.
  func Middleware(service string, opts ...Option) gin.HandlerFunc {
  	cfg := newConfig()
  	for _, opt := range opts {
  		opt(cfg)
  	}
  	return func(c *gin.Context) {
  		resource := cfg.resourceNamer(c)
  		opts := []ddtrace.StartSpanOption{
  			tracer.ServiceName(service),
  			tracer.ResourceName(resource),
  			tracer.SpanType(ext.SpanTypeWeb),
  			tracer.Tag(ext.HTTPMethod, c.Request.Method),
  			tracer.Tag(ext.HTTPURL, c.Request.URL.Path),
  			tracer.Measured(),
  		}
  		if !math.IsNaN(cfg.analyticsRate) {
  			opts = append(opts, tracer.Tag(ext.EventSampleRate, cfg.analyticsRate))
  		}
  		if spanctx, err := tracer.Extract(tracer.HTTPHeadersCarrier(c.Request.Header)); err == nil {
  			opts = append(opts, tracer.ChildOf(spanctx))
  		}
  		span, ctx := tracer.StartSpanFromContext(c.Request.Context(), "http.request", opts...)
  		defer span.Finish()
  
  		// pass the span through the request context
  		c.Request = c.Request.WithContext(ctx)
  
  		// serve the request to the next middleware
  		c.Next()
  
  		status := c.Writer.Status()
  		span.SetTag(ext.HTTPCode, strconv.Itoa(status))
  		if status >= 500 && status < 600 {
  			span.SetTag(ext.Error, fmt.Errorf("%d: %s", status, http.StatusText(status)))
  		}
  
  		if len(c.Errors) > 0 {
  			span.SetTag("gin.errors", c.Errors.String())
  		}
  	}
  }
  
  // HTML will trace the rendering of the template as a child of the span in the given context.
  func HTML(c *gin.Context, code int, name string, obj interface{}) {
  	span, _ := tracer.StartSpanFromContext(c.Request.Context(), "gin.render.html")
  	span.SetTag("go.template", name)
  	defer func() {
  		if r := recover(); r != nil {
  			err := fmt.Errorf("error rendering tmpl:%s: %s", name, r)
  			span.Finish(tracer.WithError(err))
  			panic(r)
  		} else {
  			span.Finish()
  		}
  	}()
  	c.HTML(code, name, obj)
  }
  