How to Implement Idempotent Job Processing in Go

Implement idempotent job processing by tracking completed job IDs in a persistent store and checking for existence before execution. Use a sync.Map for in-memory deduplication or a database for durability across restarts.

import (
	"sync"
)

var completedJobs = sync.Map{}

func ProcessJob(jobID string, fn func()) {
	if _, loaded := completedJobs.LoadOrStore(jobID, struct{}{}); loaded {
		return // Job already processed
	}
	fn()
}

Idempotent processing ensures that running a job multiple times produces the same result as running it once. You achieve this by recording the ID of every job you finish and skipping it if you see it again. Think of it like a to-do list where you cross off items immediately so you never do the same task twice.