pool/maxto.go

package pool

import (
	"code.squareroundforest.org/arpio/times"
	"time"
)

type maxTimeout struct {
	clock   times.Clock
	max     int
	to      time.Duration
	items   []time.Time
	lastPut int
}

func makeMaxTimeout(max int, to time.Duration) *maxTimeout {
	return &maxTimeout{
		max: max,
		to:  to,
	}
}

func (a *maxTimeout) setClock(c times.Clock) {
	a.clock = c
}

func (a *maxTimeout) Target(s Stats) (int, time.Duration) {
	if a.max <= 0 && a.to <= 0 {
		return s.Idle, 0
	}

	if a.max > 0 && a.to <= 0 {
		t := s.Idle
		if t > a.max {
			t = a.max
		}

		return t, 0
	}

	var zero time.Time
	if len(a.items) > s.Idle {
		for i := s.Idle; i < len(a.items); i++ {
			a.items[i] = zero
		}

		a.items = a.items[:s.Idle]
		if len(a.items) == 0 {
			a.items = nil
		}
	}

	now := a.clock.Now()
	for len(a.items) < s.Idle {
		a.items = append(a.items, now)
	}

	puts := s.Put - a.lastPut
	if puts > 0 && len(a.items) >= puts {
		a.lastPut = s.Put
		for i := len(a.items) - puts; i < len(a.items); i++ {
			a.items[i] = now
		}
	}

	var drop int
	for drop < len(a.items) && a.items[drop].Add(a.to).Before(now) {
		a.items[drop] = zero
		drop++
	}

	if drop > 0 {
		a.items = a.items[drop:]
	}

	if len(a.items) == 0 {
		a.items = nil
		return 0, 0
	}

	t := len(a.items)
	if a.max > 0 && t > a.max {
		t = a.max
	}

	return t, a.items[0].Add(a.to).Sub(now)
}