Function newLevelsController

levels.go:75–204

(db *DB, mf *Manifest)

}

func newLevelsController(db *DB, mf *Manifest) (*levelsController, error) {
	y.AssertTrue(db.opt.NumLevelZeroTablesStall > db.opt.NumLevelZeroTables)
	s := &levelsController{
		kv:     db,
		levels: make([]*levelHandler, db.opt.MaxLevels),
	}
	s.cstatus.levels = make([]*levelCompactStatus, db.opt.MaxLevels)

	for i := 0; i < db.opt.MaxLevels; i++ {
		s.levels[i] = newLevelHandler(db, i)
		switch i {
		case 0:
			// Do nothing.
		case 1:
			// Level 1 probably shouldn't be too much bigger than level 0.
			s.levels[i].maxTotalSize = db.opt.LevelOneSize
		default:
			s.levels[i].maxTotalSize = s.levels[i-1].maxTotalSize * int64(db.opt.LevelSizeMultiplier)
		}
		s.cstatus.levels[i] = new(levelCompactStatus)
	}

	if db.opt.InMemory {
		return s, nil
	}
	// Compare manifest against directory, check for existent/non-existent files, and remove.
	if err := revertToManifest(db, mf, getIDMap(db.opt.Dir)); err != nil {
		return nil, err
	}

	// Some files may be deleted. Let's reload.
	var flags uint32 = y.Sync
	if db.opt.ReadOnly {
		flags |= y.ReadOnly
	}

	var mu sync.Mutex
	tables := make([][]*table.Table, db.opt.MaxLevels)
	var maxFileID uint64

	// We found that using 3 goroutines allows disk throughput to be utilized to its max.
	// Disk utilization is the main thing we should focus on, while trying to read the data. That's
	// the one factor that remains constant between HDD and SSD.
	throttle := y.NewThrottle(3)

	start := time.Now()
	var numOpened int32
	tick := time.NewTicker(3 * time.Second)
	defer tick.Stop()

	for fileID, tf := range mf.Tables {
		fname := table.NewFilename(fileID, db.opt.Dir)
		select {
		case <-tick.C:
			db.opt.Infof("%d tables out of %d opened in %s\n", atomic.LoadInt32(&numOpened),
				len(mf.Tables), time.Since(start).Round(time.Millisecond))
		default:
		}