package server

import (
	"time"

	"github.com/tidwall/tile38/internal/log"
)

const bgExpireDelay = time.Second / 10

// backgroundExpiring deletes expired items from the database.
// It's executes every 1/10 of a second.
func (s *Server) backgroundExpiring() {
	for {
		if s.stopServer.on() {
			return
		}
		func() {
			s.mu.Lock()
			defer s.mu.Unlock()
			now := time.Now().UnixNano()
			var ids []string
			var msgs []*Message
			s.cols.Ascend(nil, func(v interface{}) bool {
				col := v.(*collectionKeyContainer)
				ids = col.col.Expired(now, ids[:0])
				for _, id := range ids {
					msgs = append(msgs, &Message{
						Args: []string{"del", col.key, id},
					})
				}
				return true
			})
			for _, msg := range msgs {
				_, d, err := s.cmdDel(msg)
				if err != nil {
					log.Fatal(err)
				}
				if err := s.writeAOF(msg.Args, &d); err != nil {
					log.Fatal(err)
				}
			}
			if len(msgs) > 0 {
				log.Debugf("Expired %d items\n", len(msgs))
			}
		}()
		time.Sleep(bgExpireDelay)
	}
}