wait-group.go

/*
© 2021–present Harald Rudell <harald.rudell@gmail.com> (https://haraldrudell.github.io/haraldrudell/)
ISC License
*/

package parl

import (
	"fmt"
	"sync"

	"github.com/haraldrudell/parl/perrors"
)

/*
parl.WaitGroup is like a sync.Waitgroup that can be inspected.
The Waiting method returns the number of threads waited for.
parl.WaitGroup requires no initialization.

	var wg parl.WaitGroup
	wg.Add(1)
	…
	wg.Waiting()
*/
type WaitGroup struct {
	sync.WaitGroup // Wait()
	lock           sync.Mutex
	adds           int
	dones          int
}

func InitWaitGroup(wgp *WaitGroup) {
	if wgp == nil {
		panic(perrors.NewPF("wgp cannot be nil"))
	}
	wgp.WaitGroup = sync.WaitGroup{}
	wgp.lock = sync.Mutex{}
	wgp.adds = 0
	wgp.dones = 0
}

func (wg *WaitGroup) Add(delta int) {
	wg.lock.Lock()
	defer wg.lock.Unlock()

	wg.adds += delta
	wg.WaitGroup.Add(delta)
}

func (wg *WaitGroup) Done() {
	wg.DoneBool()
}

func (wg *WaitGroup) DoneBool() (isExit bool) {
	wg.lock.Lock()
	defer wg.lock.Unlock()

	wg.dones++
	wg.WaitGroup.Done()
	return wg.dones == wg.adds
}

func (wg *WaitGroup) Count() (remaining int) {
	adds, dones := wg.Counters()
	remaining = adds - dones
	return
}

func (wg *WaitGroup) Counters() (adds int, dones int) {
	wg.lock.Lock()
	defer wg.lock.Unlock()

	adds = wg.adds
	dones = wg.dones
	return
}

func (wg *WaitGroup) IsZero() (isZero bool) {
	adds, dones := wg.Counters()
	return adds == dones
}

func (wg *WaitGroup) String() (s string) {
	adds, dones := wg.Counters()
	return fmt.Sprintf("%d(%d)", adds-dones, adds)
}