codesnips

concurrency

go 
package watch

import (
	"sync"
	"time"
)

Debounce Filesystem Change Events Before Triggering a Rebuild in Go

fsnotify debounce filewatcher
by codesnips 3 tabs
ruby 
module RequestStore
  def self.store
    Thread.current[:request_store] ||= {}
  end

  def self.fetch(key)

Hot Path Memoization (within request only)

rails performance memoization
by codesnips 4 tabs
rust 
use std::time::Duration;
use tokio_util::sync::CancellationToken;

pub struct Worker {
    id: usize,
    token: CancellationToken,

Graceful Task Shutdown in Tokio Using CancellationToken

tokio async cancellation
by codesnips 3 tabs
java 
@Configuration
@EnableAsync
public class AsyncConfig {

    @Bean(name = "orderExecutor")
    public ThreadPoolTaskExecutor orderExecutor() {

Debouncing Order Recalculations with Spring @Async and a Configured ThreadPoolTaskExecutor

spring-boot async thread-pool
by codesnips 3 tabs
sql 
CREATE TYPE outbox_status AS ENUM ('pending', 'retry', 'processing', 'done', 'dead');

CREATE TABLE outbox_events (
    id           BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    dedupe_key   TEXT        NOT NULL,
    topic        TEXT        NOT NULL,

Atomic “Read + Mark Processed” with UPDATE … RETURNING

postgres concurrency reliability
by codesnips 3 tabs
ruby 
class CounterBuffer
  DELTA_HASH = "counter:deltas".freeze

  READ_RESET = <<~LUA.freeze
    local v = redis.call('HGET', KEYS[1], ARGV[1])
    if v then redis.call('HDEL', KEYS[1], ARGV[1]) end

Debounce Expensive Counter Cache Updates with a Throttled Redis Buffer in Rails

rails redis counter-cache
by codesnips 3 tabs
go 
package main

import (
	"context"
	"log"
	"net/http"

Graceful HTTP Server Shutdown in Go with SIGINT and Context Cancellation

go http graceful-shutdown
by codesnips 2 tabs
ruby 
class AddSlugToPosts < ActiveRecord::Migration[7.1]
  def change
    add_column :posts, :slug, :string, null: false
    add_index :posts, :slug, unique: true
  end
end

Database-Backed Unique Slugs with Retry

rails postgres slugs
by codesnips 4 tabs
python 
from django.db import transaction
from django.shortcuts import get_object_or_404
from django.http import JsonResponse
from .models import Product

Django select_for_update for database locking

django python database
by Priya Sharma 1 tab
python 
import asyncio
import uuid
from dataclasses import dataclass, field
from typing import Any, Dict, Optional

Long-Polling a Background Job's Status with a Shared Result Registry in FastAPI

fastapi asyncio long-polling
by codesnips 3 tabs
lua 
-- KEYS[1] = bucket key
-- ARGV[1] = capacity, ARGV[2] = refill_per_sec, ARGV[3] = now (float seconds)
local capacity = tonumber(ARGV[1])
local rate = tonumber(ARGV[2])
local now = tonumber(ARGV[3])

Redis-Backed Token Bucket Rate Limiter as FastAPI Middleware

fastapi redis rate-limiting
by codesnips 4 tabs
rust 
use crate::hashing::double_hash;

pub struct BloomFilter {
    bits: Vec<u64>,
    m: usize, // number of bits
    k: u32,   // number of hash probes

Bloom Filter for Deduplicating Seen URLs in a Web Crawler

bloom-filter probabilistic hashing
by codesnips 3 tabs