Advanced code explainers

ruby

class ThumbnailPool
  def initialize(worker_count: 4, capacity: 100)
    @queue = SizedQueue.new(capacity)
    @running = true

A thread pool for thumbnail jobs in Ruby

concurrency thread-pool bounded-queue

Advanced 7 steps

java

public class RequestCoalescer<K, V> {
 
    private final ConcurrentHashMap<K, CompletableFuture<V>> inFlight = new ConcurrentHashMap<>();
    private final Function<K, V> loader;

Coalescing duplicate requests in Java

concurrency caching completablefuture

Advanced 6 steps

rust

use axum::{
    extract::State,
    response::sse::{Event, KeepAlive, Sse},
    Json,

Proxying an SSE chat stream in Axum

server-sent-events streaming async-generators

Advanced 10 steps

javascript

async function uploadInBatches(records, uploadFn, { batchSize = 100, concurrency = 3 } = {}) {
  const batches = [];
  for (let i = 0; i < records.length; i += batchSize) {
    batches.push(records.slice(i, i + batchSize));

Uploading records with bounded concurrency

concurrency worker-pool async-await

Advanced 8 steps

python

from copy import deepcopy
 
 
class CowSnapshot:

Copy-on-write attribute snapshots in Python

copy-on-write descriptors attribute-interception

Advanced 7 steps

php

<?php
 
namespace App\RateLimiting;

Sliding-window rate limiting with Redis sorted sets

rate-limiting redis sorted-sets

Advanced 8 steps

ruby

class CircuitBreaker
  class OpenCircuitError < StandardError; end
 
  def initialize(failure_threshold: 5, reset_timeout: 30, half_open_max: 1)

How a circuit breaker guards failing calls

state-machine fault-tolerance concurrency

Advanced 9 steps

php

<?php
 
namespace App\Http\Controllers;

Server-Sent Events in Laravel

server-sent-events streaming long-polling

Advanced 9 steps

go

package middleware
 
import (
	"crypto/sha256"

Deduplicating concurrent requests in Gin

singleflight request-coalescing middleware

Advanced 8 steps

php

<?php
 
namespace App\Actions\Imports;

Streaming CSV imports with Laravel batches

lazy-collections job-batching streaming

Advanced 9 steps

javascript

const express = require('express');
const jwt = require('jsonwebtoken');
const crypto = require('crypto');

Refresh token rotation in Express

jwt token-rotation authentication

Advanced 9 steps

python

from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import Request
from starlette.responses import JSONResponse, Response
from starlette.status import HTTP_413_REQUEST_ENTITY_TOO_LARGE

Enforcing a max request body size in FastAPI

middleware streaming request-limits

Advanced 6 steps

rust

use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::thread;
use std::time::Duration;

Graceful thread shutdown with an atomic flag

concurrency atomics memory-ordering

Advanced 7 steps

javascript

const express = require('express');
const EventEmitter = require('events');
 
const router = express.Router();

Server-Sent Events with Express

server-sent-events streaming event-emitter

Advanced 8 steps

python

import json
import time
import queue

Server-Sent Events streaming in Flask

server-sent-events streaming pub-sub

Advanced 9 steps

php

<?php
 
namespace App\Http\Middleware;

Idempotency keys in Laravel middleware

idempotency middleware caching

Advanced 8 steps

typescript

type DeepPartial<T> = T extends object
  ? { [K in keyof T]?: DeepPartial<T[K]> }
  : T;

Type-safe deep merge in TypeScript

recursion conditional-types mapped-types

Advanced 7 steps

php

<?php
 
namespace App\Models;

Debouncing Eloquent jobs in Laravel

debounce model-events queued-jobs

Advanced 7 steps