codesnips

concurrency

javascript 
class BatchLoader {
  constructor(batchFn, { cacheKeyFn = (k) => k } = {}) {
    this.batchFn = batchFn;
    this.cacheKeyFn = cacheKeyFn;
    this.cache = new Map();
    this.queue = [];

Coalescing Concurrent Reads with a DataLoader-Style Batch Loader in Node

dataloader batching graphql
by codesnips 3 tabs
go 
package mailer

import (
	"crypto/sha256"
	"encoding/hex"
	"strings"

Idempotent Email Sending with a Redis Fingerprint Set in Go

redis idempotency email
by codesnips 3 tabs
rust 
use tokio::sync::broadcast;

pub struct Shutdown {
    is_shutdown: bool,
    notify: broadcast::Receiver<()>,
}

Graceful Shutdown for a Tokio TCP Server on Ctrl-C with a Broadcast Signal

tokio async graceful-shutdown
by codesnips 3 tabs
ruby 
class InventoryLevel < ApplicationRecord
  belongs_to :warehouse

  UPSERT_COLUMNS = %w[warehouse_id sku on_hand reserved updated_at].freeze

  def self.upsert_counts(rows)

Bulk-Upsert Inventory Counts in One Query From a Sidekiq Job

rails postgres upsert
by codesnips 3 tabs
ruby 
class Order < ApplicationRecord
  class InvalidTransition < StandardError; end

  enum status: { pending: 0, paid: 1, shipped: 2, cancelled: 3 }

  has_many :order_transitions, -> { order(:created_at) }, dependent: :destroy

Order State Machine With Guarded Transitions and an Audit Trail in Rails

rails state-machine activerecord
by codesnips 3 tabs
go 
package health

import (
	"context"
	"sync"
	"time"

Concurrent Readiness Health Check Endpoint in Go with Timeouts

go health-check readiness
by codesnips 3 tabs
python 
from collections import defaultdict
from dataclasses import dataclass, field
from typing import Callable, Dict, List, Set


class CycleError(Exception):

Topological Task Scheduling With Cycle Detection and Parallel Waves

scheduling topological-sort dag
by codesnips 3 tabs
rust 
use notify::{Event, RecommendedWatcher, RecursiveMode, Watcher};
use std::path::{Path, PathBuf};
use std::sync::mpsc;

pub fn spawn_watcher(root: &Path) -> notify::Result<(RecommendedWatcher, flume::Receiver<PathBuf>)> {
    let (raw_tx, raw_rx) = mpsc::channel::<notify::Result<Event>>();

Debouncing Rapid Filesystem Events in a Rust Directory Watcher

rust filesystem notify
by codesnips 3 tabs
go 
package authtransport

import (
	"errors"
	"net/http"
)

Injecting Auth Headers via a Custom http.RoundTripper Decorator in Go

go http middleware
by codesnips 3 tabs
ruby 
require 'set'
require 'json'

class Broadcaster
  def initialize
    @mutex = Mutex.new

Stream Server-Sent Events from a Sinatra Route With Keep-Alive Pings

sinatra sse streaming
by codesnips 3 tabs
python 
import asyncio
from typing import Awaitable, Callable, Dict, TypeVar

T = TypeVar("T")

Coalesce Duplicate In-Flight Requests with an Asyncio Single-Flight Cache

asyncio concurrency caching
by codesnips 3 tabs
go 
package limit

import (
  "context"

  "golang.org/x/sync/semaphore"

Concurrency limiting with a context-aware semaphore

go concurrency context
by Leah Thompson 1 tab