store.go

//
//  tank
//
//  Import and Playlist Daemon for autoradio project
//
//
//  Copyright (C) 2017 Christian Pointner <equinox@helsinki.at>
//
//  This file is part of tank.
//
//  tank is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  any later version.
//
//  tank is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with tank. If not, see <http://www.gnu.org/licenses/>.
//

package store

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/coreos/bbolt"
)

const (
	StoreVersion = 1
)

type Store struct {
	version  int
	db       *bolt.DB
	basePath string
}

//
// Initialization and Destruction
//

func openDB(dbPath string, readOnly bool) (db *bolt.DB, version int, err error) {
	if _, err = os.Stat(dbPath); err != nil {
		if os.IsNotExist(err) {
			err = nil
		}
		return
	}
	opts := &bolt.Options{Timeout: 100 * time.Millisecond, ReadOnly: readOnly}
	db, err = bolt.Open(dbPath, 0600, opts)
	if err != nil {
		return
	}

	err = db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(infoBn))
		if b == nil {
			return errors.New("store: failed to open, bucket '" + infoBn + "'does not exist.")
		}
		bVersion := b.Get([]byte(storeVersionKey))
		if bVersion == nil {
			return errors.New("store: failed to open, no version found.")
		}
		version = btoi(bVersion)
		if version != StoreVersion {
			return fmt.Errorf("store: failed to open, wrong version: %d (expected: %d)", version, StoreVersion)
		}

		// TODO: check all group buckets??
		return nil
	})
	if err != nil {
		db.Close()
	}
	return
}

func createDB(dbPath string) (db *bolt.DB, version int, err error) {
	db, err = bolt.Open(dbPath, 0600, &bolt.Options{Timeout: 100 * time.Millisecond})
	if err != nil {
		return
	}

	err = db.Update(func(tx *bolt.Tx) error {
		b, err := tx.CreateBucket([]byte(infoBn))
		if err != nil {
			return err
		}
		version = StoreVersion
		if err := b.Put([]byte(storeVersionKey), itob(version)); err != nil {
			return err
		}

		b, err = tx.CreateBucket([]byte(groupsBn))
		if err != nil {
			return err
		}
		_, err = newGroup(b, publicGroupBn)
		return err
	})
	if err != nil {
		db.Close()
	}

	return
}

func NewStore(cfg *Config) (*Store, error) {
	dbpath := filepath.Join(cfg.BasePath, ".db.bolt")
	db, version, err := openDB(dbpath, false)
	if err != nil {
		return nil, err
	}

	if db != nil {
		return &Store{version, db, cfg.BasePath}, nil
	}

	db, version, err = createDB(dbpath)
	if err != nil {
		return nil, err
	}
	return &Store{version, db, cfg.BasePath}, nil
}

func (st *Store) Close() {
	st.db.Close()
}