Limit concurrent function executions using Go channels

limiter.go

package limiter

import (
	"errors"
	"time"
)

type Limiter struct {
	timeout time.Duration
	ch      chan struct{}
}

func NewLimiter(limit int, timeout time.Duration) *Limiter {
	return &Limiter{
		timeout: timeout,
		ch:      make(chan struct{}, limit),
	}
}

func (l *Limiter) Execute(f func()) error {
	select {
	case l.ch <- struct{}{}:
		// Added execution for running...
	case <-time.After(l.timeout):
		return errors.New("execution timed out")
	}

	// On exit, remove this execution from limit channel
	defer func() {
		<-l.ch
	}()

	f()

	return nil
}