type go.etcd.io/bbolt.pidSet

4 uses

	go.etcd.io/bbolt (current package)
		freelist.go#L18: type pidSet map[pgid]struct{}
		freelist.go#L28: 	freemaps       map[uint64]pidSet           // key is the size of continuous pages(span), value is a set which contains the starting pgids of same size
		freelist.go#L45: 		freemaps:     make(map[uint64]pidSet),
		freelist_hmap.go#L158: 	f.freemaps = make(map[uint64]pidSet)