server.go

package main

import (
	"fmt"
	"net"
	"net/http"
	"sync"
	"time"
)

type UserTask struct {
	mtx1  sync.Mutex
	mtx2  sync.Mutex
	isNew bool
}

var (
	userTaskMap map[string]*UserTask
	mapMtx      sync.Mutex
)

func main() {
	userTaskMap = make(map[string]*UserTask)

	http.HandleFunc("/", handleRequest)
	fmt.Println("Starting server on :8080")
	http.ListenAndServe(":8080", nil)
}

func handleRequest(w http.ResponseWriter, r *http.Request) {
	ip, _, err := net.SplitHostPort(r.RemoteAddr)
	if err != nil {
		http.Error(w, "Error parsing IP address", http.StatusInternalServerError)
		return
	}

	mapMtx.Lock()
	task, ok := userTaskMap[ip]
	if !ok {
		task = &UserTask{
			isNew: true,
		}
		userTaskMap[ip] = task
	}
	mapMtx.Unlock()

	task.mtx1.Lock()
	task.isNew = true
	task.mtx2.Unlock()

	go func() {
		time.Sleep(1 * time.Second)
		task.mtx2.Lock()
		task.isNew = false
		task.mtx1.Unlock()
	}()

	task.mtx2.Lock()
	if task.isNew {
		task.mtx1.Unlock()
		fmt.Fprintf(w, "Skipping request from %s\n", ip)
		return
	}

	longRunningTask(task)

	fmt.Fprintf(w, "Task completed for IP: %s\n", ip)
}

func longRunningTask(task *UserTask) {
	task.mtx2.Unlock()
	time.Sleep(5 * time.Second)
	task.mtx2.Lock()
	task.mtx2.Unlock()
}