ratelimit

ratelimit implements the x/sync/errgroup interface, but enforces a max throughput that the functions will be executed at. This is useful when making concurrent requests to backends that have either have rate limiting or cannot handle excessive throughput.

Usage

See the godoc page for full documentation.

import (
    "context"
    "fmt"
    "time"

    "github.com/cyrusaf/ratelimit"
)

func ExampleErrGroup() {
	ctx := context.Background()
	start := time.Now()

	// Create ratelimited errgroup with max 10 executions per second
	eg, ctx := ratelimit.WithContext(ctx, 10)

	// Kick off 10 goroutines.
	for i := 0; i < 10; i++ {
		// Shadow i so that it can be used in concurrent goroutines without
		// future loop iterations changing its value.
		i := i
		eg.Go(func() error {
			fmt.Printf("%d: %s\n", i, time.Since(start).Round(time.Millisecond*10))
			return nil
		})
	}

	err := eg.Wait()
	if err != nil {
		panic(err)
	}

	// Output:
	// 0: 100ms
	// 1: 200ms
	// 2: 300ms
	// 3: 400ms
	// 4: 500ms
	// 5: 600ms
	// 6: 700ms
	// 7: 800ms
	// 8: 900ms
	// 9: 1s
}