Method meta

db.go:1141–1162

meta retrieves the current meta page reference.

()

// meta retrieves the current meta page reference.
func (db *DB) meta() *common.Meta {
	// We have to return the meta with the highest txid which doesn't fail
	// validation. Otherwise, we can cause errors when in fact the database is
	// in a consistent state. metaA is the one with the higher txid.
	metaA := db.meta0
	metaB := db.meta1
	if db.meta1.Txid() > db.meta0.Txid() {
		metaA = db.meta1
		metaB = db.meta0
	}

	// Use higher meta page if valid. Otherwise, fallback to previous, if valid.
	if err := metaA.Validate(); err == nil {
		return metaA
	} else if err := metaB.Validate(); err == nil {
		return metaB
	}

	// This should never be reached, because both meta1 and meta0 were validated
	// on mmap() and we do fsync() on every write.
	panic("bolt.DB.meta(): invalid meta pages")
}

// allocate returns a contiguous block of memory starting at a given page.
func (db *DB) allocate(txid common.Txid, count int) (*common.Page, error) {