db.go

package sweetdb

import (
	"encoding/binary"
	"fmt"
	bolt "go.etcd.io/bbolt"
	"os"
	"path/filepath"
)

const (
	dbName           = "sweet.db"
	dbFilePermission = 0600
	latestDbVersion  = 1
)

var (
	// Big endian is the preferred byte order, due to cursor scans over
	// integer keys iterating in order.
	byteOrder = binary.BigEndian
)

// DB is the primary data store of the sweet daemon.
type DB struct {
	*bolt.DB
	dbPath string
}

// Open opens an existing sweetdb.
func Open(dbPath string) (*DB, error) {
	path := filepath.Join(dbPath, dbName)

	if !fileExists(path) {
		if err := createSweetDB(dbPath); err != nil {
			return nil, err
		}
	}

	bdb, err := bolt.Open(path, dbFilePermission, nil)
	if err != nil {
		return nil, err
	}

	sweetDB := &DB{
		DB:     bdb,
		dbPath: dbPath,
	}

	return sweetDB, nil
}

// Path returns the file path to the channel database.
func (d *DB) Path() string {
	return d.dbPath
}

// Wipe completely deletes all saved state within all used buckets within the
// database. The deletion is done in a single transaction, therefore this
// operation is fully atomic.
func (d *DB) Wipe() error {
	return d.Update(func(tx *bolt.Tx) error {
		err := tx.DeleteBucket(settingsBucket)
		if err != nil && err != bolt.ErrBucketNotFound {
			return err
		}

		return nil
	})
}

// createChannelDB creates and initializes a fresh version of sweetdb. In
// the case that the target path has not yet been created or doesn't yet exist,
// then the path is created. Additionally, all required top-level buckets used
// within the database are created.
func createSweetDB(dbPath string) error {
	if !fileExists(dbPath) {
		if err := os.MkdirAll(dbPath, 0700); err != nil {
			return err
		}
	}

	path := filepath.Join(dbPath, dbName)
	bdb, err := bolt.Open(path, dbFilePermission, nil)
	if err != nil {
		return err
	}

	err = bdb.Update(func(tx *bolt.Tx) error {
		if _, err := tx.CreateBucket(settingsBucket); err != nil {
			return err
		}

		meta := &Meta{
			DbVersionNumber: latestDbVersion,
		}
		return putMeta(meta, tx)
	})
	if err != nil {
		return fmt.Errorf("unable to create new channeldb")
	}

	return bdb.Close()
}

// fileExists returns true if the file exists, and false otherwise.
func fileExists(path string) bool {
	if _, err := os.Stat(path); err != nil {
		if os.IsNotExist(err) {
			return false
		}
	}

	return true
}