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badger.go
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badger.go
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package db
import (
"context"
"encoding/json"
"fmt"
"os"
"github.com/dgraph-io/badger"
"github.com/dgraph-io/badger/options"
"github.com/pkg/errors"
log "github.com/sirupsen/logrus"
"github.com/Jv0id/podsync/pkg/model"
)
const (
versionPath = "podsync/version"
feedPrefix = "feed/"
feedPath = "feed/%s"
episodePrefix = "episode/%s/"
episodePath = "episode/%s/%s" // FeedID + EpisodeID
)
// BadgerConfig represents BadgerDB configuration parameters
type BadgerConfig struct {
Truncate bool `toml:"truncate"`
FileIO bool `toml:"file_io"`
}
type Badger struct {
db *badger.DB
}
var _ Storage = (*Badger)(nil)
func NewBadger(config *Config) (*Badger, error) {
var (
dir = config.Dir
)
log.Infof("opening database %q", dir)
// Make sure database directory exists
if err := os.MkdirAll(dir, 0755); err != nil {
return nil, errors.Wrap(err, "could not mkdir database dir")
}
opts := badger.DefaultOptions(dir).
WithLogger(log.StandardLogger()).
WithTruncate(true)
if config.Badger != nil {
opts.Truncate = config.Badger.Truncate
if config.Badger.FileIO {
opts.ValueLogLoadingMode = options.FileIO
}
}
db, err := badger.Open(opts)
if err != nil {
return nil, errors.Wrap(err, "failed to open database")
}
storage := &Badger{db: db}
if err := db.Update(func(txn *badger.Txn) error {
if err := storage.setObj(txn, []byte(versionPath), CurrentVersion, false); err != nil && err != model.ErrAlreadyExists {
return err
}
return nil
}); err != nil {
return nil, errors.Wrap(err, "failed to read database version")
}
return &Badger{db: db}, nil
}
func (b *Badger) Close() error {
log.Debug("closing database")
return b.db.Close()
}
func (b *Badger) Version() (int, error) {
var (
version = -1
)
err := b.db.View(func(txn *badger.Txn) error {
return b.getObj(txn, []byte(versionPath), &version)
})
return version, err
}
func (b *Badger) AddFeed(_ context.Context, feedID string, feed *model.Feed) error {
return b.db.Update(func(txn *badger.Txn) error {
// Insert or update feed info
feedKey := b.getKey(feedPath, feedID)
if err := b.setObj(txn, feedKey, feed, true); err != nil {
return err
}
// Append new episodes
for _, episode := range feed.Episodes {
episodeKey := b.getKey(episodePath, feedID, episode.ID)
err := b.setObj(txn, episodeKey, episode, false)
if err == nil || err == model.ErrAlreadyExists {
// Do nothing
} else {
return errors.Wrapf(err, "failed to save episode %q", feedID)
}
}
return nil
})
}
func (b *Badger) GetFeed(_ context.Context, feedID string) (*model.Feed, error) {
var (
feed = model.Feed{}
feedKey = b.getKey(feedPath, feedID)
)
if err := b.db.View(func(txn *badger.Txn) error {
// Query feed
if err := b.getObj(txn, feedKey, &feed); err != nil {
return err
}
// Query episodes
if err := b.walkEpisodes(txn, feedID, func(episode *model.Episode) error {
feed.Episodes = append(feed.Episodes, episode)
return nil
}); err != nil {
return err
}
return nil
}); err != nil {
return nil, err
}
return &feed, nil
}
func (b *Badger) WalkFeeds(_ context.Context, cb func(feed *model.Feed) error) error {
return b.db.View(func(txn *badger.Txn) error {
opts := badger.DefaultIteratorOptions
opts.Prefix = b.getKey(feedPrefix)
opts.PrefetchValues = true
return b.iterator(txn, opts, func(item *badger.Item) error {
feed := &model.Feed{}
if err := b.unmarshalObj(item, feed); err != nil {
return err
}
return cb(feed)
})
})
}
func (b *Badger) DeleteFeed(_ context.Context, feedID string) error {
return b.db.Update(func(txn *badger.Txn) error {
// Feed
feedKey := b.getKey(feedPath, feedID)
if err := txn.Delete(feedKey); err != nil {
return errors.Wrapf(err, "failed to delete feed %q", feedID)
}
// Episodes
opts := badger.DefaultIteratorOptions
opts.Prefix = b.getKey(episodePrefix, feedID)
opts.PrefetchValues = false
if err := b.iterator(txn, opts, func(item *badger.Item) error {
return txn.Delete(item.KeyCopy(nil))
}); err != nil {
return errors.Wrapf(err, "failed to iterate episodes for feed %q", feedID)
}
return nil
})
}
func (b *Badger) GetEpisode(_ context.Context, feedID string, episodeID string) (*model.Episode, error) {
var (
episode model.Episode
err error
key = b.getKey(episodePath, feedID, episodeID)
)
err = b.db.View(func(txn *badger.Txn) error {
return b.getObj(txn, key, &episode)
})
return &episode, err
}
func (b *Badger) UpdateEpisode(feedID string, episodeID string, cb func(episode *model.Episode) error) error {
var (
key = b.getKey(episodePath, feedID, episodeID)
episode model.Episode
)
return b.db.Update(func(txn *badger.Txn) error {
if err := b.getObj(txn, key, &episode); err != nil {
return err
}
if err := cb(&episode); err != nil {
return err
}
if episode.ID != episodeID {
return errors.New("can't change episode ID")
}
return b.setObj(txn, key, &episode, true)
})
}
func (b *Badger) DeleteEpisode(feedID, episodeID string) error {
key := b.getKey(episodePath, feedID, episodeID)
return b.db.Update(func(txn *badger.Txn) error {
return txn.Delete(key)
})
}
func (b *Badger) WalkEpisodes(ctx context.Context, feedID string, cb func(episode *model.Episode) error) error {
return b.db.View(func(txn *badger.Txn) error {
return b.walkEpisodes(txn, feedID, cb)
})
}
func (b *Badger) walkEpisodes(txn *badger.Txn, feedID string, cb func(episode *model.Episode) error) error {
opts := badger.DefaultIteratorOptions
opts.Prefix = b.getKey(episodePrefix, feedID)
opts.PrefetchValues = true
return b.iterator(txn, opts, func(item *badger.Item) error {
feed := &model.Episode{}
if err := b.unmarshalObj(item, feed); err != nil {
return err
}
return cb(feed)
})
}
func (b *Badger) iterator(txn *badger.Txn, opts badger.IteratorOptions, callback func(item *badger.Item) error) error {
iter := txn.NewIterator(opts)
defer iter.Close()
for iter.Rewind(); iter.Valid(); iter.Next() {
item := iter.Item()
if err := callback(item); err != nil {
return err
}
}
return nil
}
func (b *Badger) getKey(format string, a ...interface{}) []byte {
resourcePath := fmt.Sprintf(format, a...)
fullPath := fmt.Sprintf("podsync/v%d/%s", CurrentVersion, resourcePath)
return []byte(fullPath)
}
func (b *Badger) setObj(txn *badger.Txn, key []byte, obj interface{}, overwrite bool) error {
if !overwrite {
// Overwrites are not allowed, make sure there is no object with the given key
_, err := txn.Get(key)
if err == nil {
return model.ErrAlreadyExists
} else if err == badger.ErrKeyNotFound {
// Key not found, do nothing
} else {
return errors.Wrap(err, "failed to check whether key exists")
}
}
data, err := b.marshalObj(obj)
if err != nil {
return errors.Wrapf(err, "failed to serialize object for key %q", key)
}
return txn.Set(key, data)
}
func (b *Badger) getObj(txn *badger.Txn, key []byte, out interface{}) error {
item, err := txn.Get(key)
if err != nil {
if err == badger.ErrKeyNotFound {
return model.ErrNotFound
}
return err
}
return b.unmarshalObj(item, out)
}
func (b *Badger) marshalObj(obj interface{}) ([]byte, error) {
return json.Marshal(obj)
}
func (b *Badger) unmarshalObj(item *badger.Item, out interface{}) error {
return item.Value(func(val []byte) error {
return json.Unmarshal(val, out)
})
}