// Package pool tracks worker busy state for one worker type. Workers are
// spawn domains reached over channels; the pool owns only the scheduling
// state, and the caller owns the channels and the spawned domains.
package pool

// Pool tracks which worker of a type is currently processing a request.
type Pool struct {
	Busy []bool
}

// NewPool creates a Pool with capacity n.
func NewPool(n int32) (p Pool) {
	return Pool{Busy: []bool{:n}}
}

// Len returns the number of workers.
func (p *Pool) Len() (n int32) { return len(p.Busy) }

// IdleIndex returns the index of the first idle worker, or -1 if all busy.
func (p *Pool) IdleIndex() (n int32) {
	for i, busy := range p.Busy {
		if !busy {
			return i
		}
	}
	return -1
}