codesnips

cron

ruby 
class Cart < ApplicationRecord
  has_many :cart_items, dependent: :destroy

  EXPIRY_WINDOW = 2.hours

  scope :active, -> { where(state: :active) }

Expire Stale Shopping Carts With a Rails Scope and a Recurring Reaper Job

rails activerecord background-jobs
by codesnips 3 tabs
typescript 
import { Pool } from "pg";

async function keyFor(pool: Pool, name: string): Promise<string> {
  const { rows } = await pool.query<{ key: string }>(
    "SELECT hashtextextended($1, 0) AS key",
    [name]

Postgres advisory lock for one-at-a-time work

postgres concurrency reliability
by codesnips 3 tabs
go 
package scheduler

import (
	"context"
	"log"
	"sync"

Graceful Cron-Style Scheduler in Go With Ticker and Context Cancellation

scheduler ticker context
by codesnips 3 tabs
ruby 
class DailySignupRollup < ApplicationRecord
  validates :day, presence: true, uniqueness: true
  validates :total, :verified, numericality: { greater_than_or_equal_to: 0 }

  scope :for_range, ->(from, to) do
    where(day: from.to_date..to.to_date).order(:day)

Nightly Signup Rollups in Rails with a Scheduled Job and Upsert

rails postgres background-jobs
by codesnips 3 tabs
ruby 
namespace :cleanup do
  desc "Enqueue a job to purge expired sessions"
  task expired_sessions: :environment do
    job = ExpiredSessionCleanupJob.perform_later
    Rails.logger.info("[cleanup:expired_sessions] enqueued job #{job.job_id}")
  end

Recurring Cleanup with a Rake Task and an Idempotent Active Job in Rails

rails background-jobs active-job
by codesnips 4 tabs
typescript 
export interface CronFields {
  minute: Set<number>;
  hour: Set<number>;
  dayOfMonth: Set<number>;
  month: Set<number>;
  dayOfWeek: Set<number>;

Cron-Expression Scheduler with Field Parser and a Tick Loop in TypeScript

cron scheduler parser
by codesnips 3 tabs