forked from lyricat/tattoo
/
storage.go
244 lines (223 loc) · 5.93 KB
/
storage.go
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package webapp
import (
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"os"
"path"
"path/filepath"
"time"
)
const (
OP_SAVE = 0
)
type Storage interface {
Get(string) string
Set(string) string
Delete(string) string
}
type StorageStat struct {
GetCount int64
SetCount int64
DeleteCount int64
HasCount int64
SaveIndexCount int64
}
type StorageCmdItem struct {
Op int
Arg1 interface{}
}
type FileStorage struct {
Path string
Mode int
Index map[string]string
Stat StorageStat
// @TODO
GetChan chan string
SetChan chan string
CmdChan chan *StorageCmdItem
}
const (
FILE_STORAGE_MODE_SINGLE = 0
FILE_STORAGE_MODE_MULIPLE = 1
)
const (
ERROR_UNKNOWN = "Unknown Error"
ERROR_KEY_NOT_EXISTS = "Key doesn't exists"
ERROR_IMPERMEABLE_KEY = "Impereable Key"
)
func (fs *FileStorage) Init(path string, mode int) error {
fs.Path = path
fs.Mode = mode
fs.CmdChan = make(chan *StorageCmdItem)
fs.GetChan = make(chan string)
fs.SetChan = make(chan string)
fs.Index = make(map[string]string)
fs.Index["*"] = "placeholder"
indexPath := fs.getIndexFilePath()
_, err := ioutil.ReadFile(indexPath)
if err != nil {
fmt.Println("Read index file failed, create new one:", err)
dir, _ := filepath.Split(indexPath)
os.MkdirAll(dir, 0755)
fs.SaveIndex()
}
fs.LoadIndex()
go fs.Master()
go func() {
for {
time.Sleep(120 * 1e9)
cmd := new(StorageCmdItem)
cmd.Op = OP_SAVE
fs.CmdChan <- cmd
}
}()
return nil
}
func (fs *FileStorage) Master() {
for {
select {
case cmd := <-fs.CmdChan:
if cmd.Op == OP_SAVE {
fs.SaveIndex()
}
case v := <-fs.GetChan:
// @TODO get value
print(v)
case v := <-fs.SetChan:
// @TODO set value
print(v)
}
}
}
func (fs *FileStorage) Get(key string) ([]byte, error) {
if key == "*" {
return nil, errors.New(ERROR_IMPERMEABLE_KEY)
}
fs.Stat.GetCount++
if fs.Mode == FILE_STORAGE_MODE_SINGLE {
if val, ok := fs.Index[key]; ok {
return []byte(val), nil
} else {
return nil, errors.New(ERROR_KEY_NOT_EXISTS)
}
} else if fs.Mode == FILE_STORAGE_MODE_MULIPLE {
if _, ok := fs.Index[key]; ok {
valueFilePath := path.Join(fs.Path, key)
value, err := ioutil.ReadFile(valueFilePath)
if err != nil {
fmt.Println("FileStorage.Get, Read file failed:", err)
return nil, err
}
return value, nil
} else {
return nil, errors.New(ERROR_KEY_NOT_EXISTS)
}
}
return nil, errors.New(ERROR_UNKNOWN)
}
func (fs *FileStorage) Has(key string) bool {
if key == "*" {
return false
}
fs.Stat.HasCount++
if _, ok := fs.Index[key]; ok {
return true
}
return false
}
func (fs *FileStorage) Set(key string, value []byte) error {
fs.Stat.SetCount++
if fs.Mode == FILE_STORAGE_MODE_SINGLE {
fs.Index[key] = string(value)
} else if fs.Mode == FILE_STORAGE_MODE_MULIPLE {
valueFilePath := path.Join(fs.Path, key)
fs.Index[key] = valueFilePath
if err := ioutil.WriteFile(valueFilePath, value, 0644); err != nil {
return err;
}
}
return nil
}
func (fs *FileStorage) GetString(key string) (string, error) {
str, err := fs.Get(key)
if err != nil {
return "", err
}
return string(str), err
}
func (fs *FileStorage) SetString(key string, value string) error {
return fs.Set(key, []byte(value))
}
// Gets string form storage assigned with specified key, coverts it to json object
// and returns.
// if this key doesn't exists or failed to parse json, return nil, err
func (fs *FileStorage) GetJSON(key string) (interface{}, error) {
var jsobj interface{}
str, err := fs.Get(key)
if err != nil {
return nil, err
}
if err := json.Unmarshal(str, &jsobj); err != nil {
fmt.Printf("FileStorage.GetJSON, Unmarshal json failed (%v):%s\n", key, err)
return nil, err
}
return jsobj, nil
}
func (fs *FileStorage) SetJSON(key string, value interface{}) error {
str, err := json.Marshal(value)
if err != nil {
fmt.Printf("FileStorage.SetJSON, Marshal json failed (%v):%s\n", value, err)
return err
}
return fs.Set(key, str)
}
func (fs *FileStorage) Delete(key string) {
fs.Stat.DeleteCount++
if fs.Mode == FILE_STORAGE_MODE_SINGLE {
delete(fs.Index, key)
} else if fs.Mode == FILE_STORAGE_MODE_MULIPLE {
delete(fs.Index, key)
valueFilePath := path.Join(fs.Path, key)
os.Remove(valueFilePath)
}
}
func (fs *FileStorage) Count() int {
return len(fs.Index)
}
func (fs *FileStorage) SaveIndex() error {
indexPath := fs.getIndexFilePath()
buff, err := json.Marshal(fs.Index)
if err != nil {
fmt.Printf("FileStorage.SaveIndex, Marshal json failed (%v):%s\n", indexPath, err)
return err
}
fs.Stat.SaveIndexCount++
if err := ioutil.WriteFile(indexPath, buff, 0644); err != nil {
return err
}
return nil
}
func (fs *FileStorage) LoadIndex() error {
indexPath := fs.getIndexFilePath()
buff, err := ioutil.ReadFile(indexPath)
if err != nil {
fmt.Println("FileStorage.LoadIndex, Read file failed:", err)
return err
}
if err := json.Unmarshal(buff, &fs.Index); err != nil {
fmt.Printf("FileStorage.LoadIndex, Unmarshal json failed (%v):%s\n", indexPath, err)
return err
}
return nil
}
func (fs *FileStorage) getIndexFilePath() string {
var indexPath string
if fs.Mode == FILE_STORAGE_MODE_SINGLE {
indexPath = fs.Path
} else if fs.Mode == FILE_STORAGE_MODE_MULIPLE {
indexPath = path.Join(fs.Path, "index.json")
}
return indexPath
}