Pochta jo'natmasini kuzatish sahifasida "jo'natildi", "yo'lda", "yetkazildi" kabi holatlarni ko'rasiz — bu sizga jo'natma HOZIR qayerda ekanini aytadi, hatto siz uni jismonan ko'rmasangiz ham. Bizning Task Queue'da ham xuddi shunday — foydalanuvchi vazifasini yuborgandan keyin, uning HOZIRGI holatini (pending, running, completed, failed) BILISHNI xohlaydi.

package main

import (
	"fmt"
	"sync"
)

type TaskStatus string

const (
	StatusPending   TaskStatus = "pending"
	StatusRunning   TaskStatus = "running"
	StatusCompleted TaskStatus = "completed"
)

// StatusTracker — barcha vazifalarning holatini markazlashtirib saqlaydi
type StatusTracker struct {
	mu       sync.RWMutex
	statuses map[string]TaskStatus
}

func NewStatusTracker() *StatusTracker {
	return &StatusTracker{statuses: make(map[string]TaskStatus)}
}

func (t *StatusTracker) SetStatus(taskID string, status TaskStatus) {
	t.mu.Lock()
	defer t.mu.Unlock()
	t.statuses[taskID] = status
}

func (t *StatusTracker) GetStatus(taskID string) (TaskStatus, bool) {
	t.mu.RLock()
	defer t.mu.RUnlock()
	status, ok := t.statuses[taskID]
	return status, ok
}

func main() {
	tracker := NewStatusTracker()
	tracker.SetStatus("task-1", StatusPending)
	tracker.SetStatus("task-1", StatusRunning)
	tracker.SetStatus("task-1", StatusCompleted)

	status, _ := tracker.GetStatus("task-1")
	fmt.Println(status)
}

StatusTracker — "URL Shortener"dagi Store bilan bir xil naqsh (sync.RWMutex + xarita), lekin endi vazifaning "hozirgi holatini" saqlaydi. Worker vazifani BOSHLASHDAN oldin SetStatus(id, StatusRunning), tugatgandan keyin SetStatus(id, StatusCompleted) chaqiradi — bu orqali TASHQI dunyo (masalan HTTP API orqali, keyingi darslarda) istalgan vaqtda vazifaning holatini SO'RASHI mumkin.

Bu — "Distributed Tracing Basics" darsida ko'rgan g'oyaning yana bir ko'rinishi: vazifaning "hayoti" davomida sodir bo'lgan HAR BIR o'zgarish, MARKAZIY bir joyda kuzatib boriladi, shuning uchun istalgan vaqtda "bu vazifa hozir qayerda?" degan savolga javob berish mumkin.