codesnips

concurrency

python 
CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379/1",
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient",

Custom DRF Throttle Class for a Public API With Sliding-Window Rate Limits

django drf rate-limiting
by codesnips 3 tabs
go 
package pool

import "context"

type Job func(ctx context.Context) error

Bounded worker pool with backpressure

go concurrency worker-pool
by Leah Thompson 1 tab
ruby 
class CreateAccountsAndLedger < ActiveRecord::Migration[7.1]
  def change
    create_table :accounts do |t|
      t.string :name, null: false
      t.string :currency, null: false, default: "USD"
      t.bigint :balance_cents, null: false, default: 0

Atomic Account Transfers in Rails With Row Locks and a Balance Service

rails postgres transactions
by codesnips 4 tabs
rust 
use std::sync::Arc;
use std::time::Duration;

use futures::stream::{FuturesUnordered, StreamExt};
use reqwest::Client;
use tokio::sync::Semaphore;

Bounded Concurrent HTTP Fan-Out With FuturesUnordered and Semaphore in Rust

rust async tokio
by codesnips 3 tabs
ruby 
class TypingPresence
  EXPIRE_AFTER = 6 # seconds

  def initialize(room, redis: Redis.current)
    @room = room
    @redis = redis

Broadcast Typing Indicators in Rails Chat with ActionCable and a Redis Presence Tracker

rails actioncable websockets
by codesnips 3 tabs
go 
package worker

import "context"

func (p *Pool) Submit(job Job) error {
	// Reject fast if draining, otherwise enqueue with backpressure.

Graceful Drain of In-Flight Jobs Before Worker Shutdown in Go

go graceful-shutdown concurrency
by codesnips 3 tabs
ruby 
class CreateIdempotencyKeys < ActiveRecord::Migration[7.1]
  def change
    create_table :idempotency_keys do |t|
      t.string :key, null: false
      t.string :request_path, null: false
      t.datetime :locked_at

Idempotent Form Submissions in Rails with an Idempotency-Key Column and before_action Guard

rails idempotency postgres
by codesnips 4 tabs
ruby 
module ConnectionHealth
  extend ActiveSupport::Concern

  def with_fresh_connection
    conn = ActiveRecord::Base.connection
    conn.verify! # pings and reconnects if the socket is dead

Keep DB Connections Healthy in Long Jobs

rails activerecord background-jobs
by codesnips 3 tabs
typescript 
import type { Redis } from "ioredis";

export interface StoredResponse {
  status: "pending" | "completed";
  fingerprint: string;
  httpStatus?: number;

Idempotent POST Requests in Express with a Redis-Backed Middleware

express redis idempotency
by codesnips 3 tabs
java 
public final class Debouncer implements AutoCloseable {

    private final ScheduledExecutorService scheduler;
    private final long delayMillis;
    private final AtomicReference<ScheduledFuture<?>> pending = new AtomicReference<>();

Debouncing Rapid Method Calls in Java with a Scheduler and Cancellable Futures

java concurrency debounce
by codesnips 3 tabs
go 
package metrics

import "time"

type bucket struct {
	start time.Time

Time-Bucketed Metric Aggregation With a Concurrent Ring of Windows in Go

go metrics time-series
by codesnips 3 tabs
rust 
use std::sync::{Arc, Mutex};
use std::thread;

fn main() {
    let counter = Arc::new(Mutex::new(0));
    let mut handles = vec![];

Arc and Mutex for safe shared mutable state across threads

rust concurrency threading
by Marcus Chen 1 tab