channel/limited_runner.go

package channel

// LimitedRunner is a Runner which runs its methods
// in a pre-defined amount of routines
type LimitedRunner struct {
	limiter chan struct{}
}

var _ Runner = &LimitedRunner{}

// NewLimitedRunner returns a new LimitedRunner with the given amount
// of allowed routines
func NewLimitedRunner(routineLimit int) *LimitedRunner {
	return &LimitedRunner{
		limiter: make(chan struct{}, routineLimit),
	}
}

// Run blocks if the limit is currently exceeded.
// It blocks until a routine becomes available again.
// For non-blocking behavior, use go syntax
func (r *LimitedRunner) Run(f func()) {
	r.limiter <- struct{}{}
	go func() {
		defer func() { <-r.limiter }()
		f()
	}()
}