Idempotency Keys

Idempotentlik kalitlari

Bankomatdan pul yechayotganda, tarmoq bir lahzaga uzilib, ekranda "kutilmoqda" chiqib qoladi. Siz яна "tasdiqlash" tugmasini bosasiz. Yaxshi ishlab chiqilgan bankomat buni BILADI: u bitta AMALNI ikki marta bajarmaydi, chunki u har bir so'rovni NOYOB "amal raqami" bilan belgilaydi va shu raqamni ALLAQACHON bajarilgan bo'lsa, natijani QAYTA HISOBLAMASDAN eski natijani qaytaradi. Idempotentlik kaliti (Idempotency Key) — API'da aynan shu himoyani beradi: mijoz HAR BIR mantiqiy amal uchun noyob kalit yuboradi, server esa bitta kalitni IKKI MARTA bajarmaydi.

example.go

package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strconv"
	"strings"
	"sync"
)

type Book struct {
	ID     string  `json:"id"`
	Title  string  `json:"title"`
	Author string  `json:"author"`
	Price  float64 `json:"price"`
}

type BookStore struct {
	mu     sync.Mutex
	books  map[string]*Book
	nextID int
}

func NewBookStore() *BookStore { return &BookStore{books: make(map[string]*Book)} }

func (s *BookStore) Create(title, author string, price float64) *Book {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.nextID++
	id := strconv.Itoa(s.nextID)
	book := &Book{ID: id, Title: title, Author: author, Price: price}
	s.books[id] = book
	return book
}

type IdempotencyStore struct {
	mu      sync.Mutex
	results map[string]*Book
}

// GetOrCreate — key ALLAQACHON ko'rilgan bo'lsa, ESKI natijani qaytaradi (replayed=true);
// aks holda create() ni chaqirib, natijani key bilan ESLAB QOLADI
func (s *IdempotencyStore) GetOrCreate(key string, create func() *Book) (book *Book, replayed bool) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if existing, ok := s.results[key]; ok {
		return existing, true
	}
	book = create()
	s.results[key] = book
	return book, false
}

func main() {
	store := NewBookStore()
	idem := &IdempotencyStore{results: make(map[string]*Book)}

	mux := http.NewServeMux()
	mux.HandleFunc("POST /books", func(w http.ResponseWriter, r *http.Request) {
		key := r.Header.Get("Idempotency-Key")
		var req struct {
			Title  string  `json:"title"`
			Author string  `json:"author"`
			Price  float64 `json:"price"`
		}
		json.NewDecoder(r.Body).Decode(&req)

		book, replayed := idem.GetOrCreate(key, func() *Book {
			return store.Create(req.Title, req.Author, req.Price)
		})
		if replayed {
			w.Header().Set("X-Idempotent-Replayed", "true")
		}
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusCreated)
		json.NewEncoder(w).Encode(book)
	})

	body := `{"title":"Go bilan tanishuv","author":"A. Karimov","price":45000}`

	req1 := httptest.NewRequest("POST", "/books", strings.NewReader(body))
	req1.Header.Set("Idempotency-Key", "key-123")
	rec1 := httptest.NewRecorder()
	mux.ServeHTTP(rec1, req1)
	fmt.Println("1-urinish, replayed:", rec1.Header().Get("X-Idempotent-Replayed"))

	req2 := httptest.NewRequest("POST", "/books", strings.NewReader(body))
	req2.Header.Set("Idempotency-Key", "key-123")
	rec2 := httptest.NewRecorder()
	mux.ServeHTTP(rec2, req2)
	fmt.Println("2-urinish (tarmoq qayta yuborgan), replayed:", rec2.Header().Get("X-Idempotent-Replayed"))

	fmt.Println("bazadagi kitoblar soni:", len(store.books))
}

IdempotencyStore.GetOrCreate — MARKAZIY g'oyani ifodalaydi: key (mijoz Idempotency-Key sarlavhasida yuborgan noyob satr) ALLAQACHON results xaritasida bo'lsa, create() funksiyasi UMUMAN chaqirilmaydi — ESKI natija QAYTARILADI. Aks holda, create() chaqiriladi VA natija key bilan SAQLANADI, keyingi safar QAYTA ishlatish uchun.

E'tibor bering: ikkinchi so'rov (xuddi shu "key-123" bilan) store.Create ni UMUMAN chaqirmadi — natijada store.booksda FAQAT bitta kitob bor, garchi POST /books IKKI marta chaqirilgan bo'lsa ham. Bu — HAQIQIY hayotda mijoz "internet uzildi, yana bosayapman" deganda YUZ beradigan vaziyatni AYNAN takrorlaydi: server bitta AMALNI IKKI MARTA bajarmaydi.

>_ Exercise

Idempotentlikning "faqat BIR KALIT uchun" ishlashini isbotlang.

•yordamchi send(key string) funksiyasini yozing: berilgan Idempotency-Key bilan bitta POST /books so'rovi yuborsin
•send("key-123") ni IKKI marta chaqiring (xuddi shu kalit — tarmoq qayta yuborgani)
•send("key-456") ni BIR marta chaqiring (BOSHQA kalit — bu YANGI, mustaqil amal)
•oxirida store.books xaritasidagi kitoblar SONINI chop eting

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Key Takeaway

Key Takeaway:

Idempotentlik kaliti — mijoz tarmoq xatosi tufayli BIR XIL so'rovni QAYTA yuborganda, serverning uni IKKI MARTA bajarib yubormasligini kafolatlaydi; kalit ESLAB QOLINGAN natijani qaytarish orqali, amal FAQAT bir marta haqiqatan sodir bo'ladi.

NEXT UP

API Versioning Strategies

OUTPUT

$ go run main.go
Kodingizni ishga tushiring