Advanced code explainers

go

package theme
 
import (
	"fmt"

Per-tenant HTML templates with Gin's renderer

multi-tenancy concurrency html-templates

Advanced 8 steps

python

import time
import threading
from enum import Enum
from functools import wraps

Building a circuit breaker in Python

circuit-breaker resilience decorators

Advanced 7 steps

typescript

import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent, HttpErrorResponse } from '@angular/common/http';
import { BehaviorSubject, Observable, throwError } from 'rxjs';
import { catchError, filter, take, switchMap } from 'rxjs/operators';

Refreshing auth tokens in an Angular interceptor

http-interceptor token-refresh rxjs

Advanced 8 steps

php

<?php
 
namespace App\Http\Middleware;

Idempotent requests with Laravel middleware

idempotency middleware caching

Advanced 8 steps

python

from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector
from django.core.cache import cache
from django.db.models import F
from django.http import JsonResponse

Ranked full-text search in Django

full-text-search debouncing caching

Advanced 9 steps

java

@Repository
public interface OrderRepository extends JpaRepository<Order, Long> {
 
    @Query("""

Keyset pagination with Spring Data JPA

pagination cursor jpa

Advanced 8 steps

java

@RestController
@RequestMapping("/api/quotes")
public class QuoteStreamController {

Streaming market quotes with Spring WebFlux

reactive-streams backpressure server-sent-events

Advanced 9 steps

javascript

import { useState, useCallback, useRef } from 'react';
 
function LikeButton({ postId, initialLiked, initialCount }) {
  const [liked, setLiked] = useState(initialLiked);

Optimistic like button with React

optimistic-ui abortcontroller error-handling

Advanced 7 steps

java

@Component
required to import
public class OutboxEventPublisher {

The transactional outbox pattern in Spring

transactional-outbox event-driven reliability

Advanced 7 steps

java

@RestController
@RequestMapping("/api/payments")
public class PaymentController {

Polymorphic payment requests in Spring

polymorphic deserialization sealed interfaces bean validation

Advanced 7 steps

php

<?php
 
namespace App\Services;

Optimistic locking on invoices in Laravel

optimistic-locking transactions concurrency

Advanced 6 steps

rust

use axum::{
    async_trait,
    body::Bytes,
    extract::FromRequest,

A strict JSON extractor in Axum

extractors traits content-negotiation

Advanced 7 steps

typescript

export class Semaphore {
  private available: number;
  private readonly waiters: Array<() => void> = [];

Building an async Semaphore in TypeScript

concurrency async-await promises

Advanced 6 steps

php

<?php
 
function fetchAll(array $urls, int $concurrency = 10, int $timeout = 15): array
{

Bounded-concurrency HTTP fetching with curl_multi

concurrency http curl

Advanced 8 steps

php

<?php
 
namespace App\Support;

How TOTP codes are generated in PHP

totp hmac two-factor-auth

Advanced 7 steps

java

@RestController
@RequestMapping("/api/notifications")
public class NotificationStreamController {

Server-Sent Events per user in Spring

server-sent-events concurrency event-driven

Advanced 8 steps

javascript

import { useState, useRef, useCallback, useLayoutEffect } from "react";
 
export function useResizeObserver({ debounce = 0 } = {}) {
  const [size, setSize] = useState({ width: 0, height: 0 });

A resize-observing hook in React

custom-hook resizeobserver callback-ref

Advanced 8 steps

ruby

class InventoryItem < ApplicationRecord
  belongs_to :warehouse
 
  validates :quantity, numericality: { greater_than_or_equal_to: 0 }

Safe inventory updates in Rails

concurrency pessimistic-locking optimistic-locking

Advanced 7 steps