http

// Licensed to SkyAPM org under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. SkyAPM org licenses this file to you 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 main

import (
	"fmt"
	"log"
	"net/http"
	"net/http/httptest"
	"time"

	"github.com/gorilla/mux"

	"github.com/SkyAPM/go2sky"
	"github.com/SkyAPM/go2sky/reporter"
)

func main() {
	// Use gRPC reporter for production
	r, err := reporter.NewLogReporter()
	if err != nil {
		log.Fatalf("new reporter error %v \n", err)
	}
	defer r.Close()

	tracer, err := go2sky.NewTracer("example", go2sky.WithReporter(r))
	if err != nil {
		log.Fatalf("create tracer error %v \n", err)
	}
	tracer.WaitUntilRegister()

	sm, err := NewServerMiddleware(tracer)
	if err != nil {
		log.Fatalf("create server middleware error %v \n", err)
	}

	client, err := NewClient(tracer)
	if err != nil {
		log.Fatalf("create client error %v \n", err)
	}

	router := mux.NewRouter()

	// create test server
	ts := httptest.NewServer(sm(router))
	defer ts.Close()

	// add handlers
	router.Methods("GET").Path("/middle").HandlerFunc(middleFunc(client, ts.URL))
	router.Methods("POST").Path("/end").HandlerFunc(endFunc())

	// call end service
	request, err := http.NewRequest("GET", fmt.Sprintf("%s/middle", ts.URL), nil)
	if err != nil {
		log.Fatalf("unable to create http request: %+v\n", err)
	}
	res, err := client.Do(request)
	if err != nil {
		log.Fatalf("unable to do http request: %+v\n", err)
	}
	_ = res.Body.Close()
	time.Sleep(time.Second)

}

func middleFunc(client *http.Client, url string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		log.Printf("middle func called with method: %s\n", r.Method)

		// do some operation
		time.Sleep(100 * time.Millisecond)

		newRequest, err := http.NewRequest("POST", url+"/end", nil)
		if err != nil {
			log.Printf("unable to create client: %+v\n", err)
			http.Error(w, err.Error(), 500)
			return
		}

		//Link the context of entry and exit spans
		newRequest = newRequest.WithContext(r.Context())

		res, err := client.Do(newRequest)
		if err != nil {
			log.Printf("call to end fund returned error: %+v\n", err)
			http.Error(w, err.Error(), 500)
			return
		}
		_ = res.Body.Close()
	}
}

func endFunc() http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		log.Printf("end func called with method: %s\n", r.Method)
		time.Sleep(50 * time.Millisecond)
	}
}