forked from gophercises/task
/
store.go
156 lines (126 loc) · 2.97 KB
/
store.go
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package store
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"time"
"github.com/golang/protobuf/proto"
"github.com/movaua/task/pkg/model"
bolt "go.etcd.io/bbolt"
)
var (
// bucket is tasks backet name
bucket = []byte("tasks")
)
// Store interacts with persistent storage
type Store interface {
Close() error
Create(task *model.Task) error
Read(id uint64) (*model.Task, error)
Update(task *model.Task) error
Delete(id uint64) error
List() ([]*model.Task, error)
}
// New creates Store
func New(filename string) (Store, error) {
db, err := bolt.Open(filename, 0600, &bolt.Options{
Timeout: time.Second,
})
if err != nil {
return nil, err
}
if err := db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucketIfNotExists(bucket)
if err != nil {
return fmt.Errorf("create bucket: %w", err)
}
return nil
}); err != nil {
return nil, err
}
return &storage{db: db}, nil
}
type storage struct {
db *bolt.DB
}
func (s *storage) Close() error {
return s.db.Close()
}
func (s *storage) Create(task *model.Task) error {
return s.db.Update(func(tx *bolt.Tx) error {
// Retrieve the tasks bucket.
// This should be created when the DB is first opened.
b := tx.Bucket(bucket)
// Generate ID for the task.
// This returns an error only if the Tx is closed or not writeable.
// That can't happen in an Update() call so I ignore the error check.
id, _ := b.NextSequence()
task.Id = id
buf, err := proto.Marshal(task)
if err != nil {
return err
}
// Persist bytes to tasks bucket.
return b.Put(itob(task.Id), buf)
})
}
func (s *storage) Read(id uint64) (*model.Task, error) {
var task model.Task
if err := s.db.View(func(tx *bolt.Tx) error {
// Assume bucket exists and has keys
b := tx.Bucket(bucket)
c := b.Cursor()
id := itob(id)
k, v := c.Seek(id)
if bytes.Compare(k, id) != 0 {
return errors.New("read: task is not found")
}
return proto.Unmarshal(v, &task)
}); err != nil {
return nil, err
}
return &task, nil
}
func (s *storage) Update(task *model.Task) error {
return s.db.Update(func(tx *bolt.Tx) error {
b := tx.Bucket(bucket)
buf, err := proto.Marshal(task)
if err != nil {
return err
}
return b.Put(itob(task.Id), buf)
})
}
func (s *storage) Delete(id uint64) error {
return s.db.Update(func(tx *bolt.Tx) error {
b := tx.Bucket(bucket)
id := itob(id)
return b.Delete(id)
})
}
func (s *storage) List() ([]*model.Task, error) {
var tasks []*model.Task
if err := s.db.View(func(tx *bolt.Tx) error {
// Assume bucket exists and has keys
b := tx.Bucket(bucket)
c := b.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
var task model.Task
if err := proto.Unmarshal(v, &task); err != nil {
return err
}
tasks = append(tasks, &task)
}
return nil
}); err != nil {
return nil, err
}
return tasks, nil
}
// itob returns an 8-byte big endian representation of v.
func itob(v uint64) []byte {
b := make([]byte, 8)
binary.BigEndian.PutUint64(b, v)
return b
}