minio/pkg/quick/quick.go

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/*
* Quick - Quick key value store for config files and persistent state files
*
* Minio Client (C) 2015 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package quick
import (
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"os"
"reflect"
"runtime"
"strings"
"sync"
"github.com/fatih/structs"
"github.com/minio/minio/pkg/iodine"
"github.com/minio/minio/pkg/utils/atomic"
)
// Config - generic config interface functions
type Config interface {
String() string
Version() string
Save(string) error
Load(string) error
Data() interface{}
Diff(Config) ([]structs.Field, error)
DeepDiff(Config) ([]structs.Field, error)
}
// config - implements quick.Config interface
type config struct {
data *interface{}
lock *sync.RWMutex
}
// CheckData - checks the validity of config data. Data sould be of type struct and contain a string type field called "Version"
func CheckData(data interface{}) error {
if !structs.IsStruct(data) {
return iodine.New(errors.New("Invalid argument type. Expecing \"struct\" type."), nil)
}
st := structs.New(data)
f, ok := st.FieldOk("Version")
if !ok {
return iodine.New(fmt.Errorf("Invalid type of struct argument. No [%s.Version] field found.", st.Name()), nil)
}
if f.Kind() != reflect.String {
return iodine.New(fmt.Errorf("Invalid type of struct argument. Expecting \"string\" type [%s.Version] field.", st.Name()), nil)
}
return nil
}
// New - instantiate a new config
func New(data interface{}) (Config, error) {
err := CheckData(data)
if err != nil {
return nil, err
}
d := new(config)
d.data = &data
d.lock = new(sync.RWMutex)
return d, nil
}
// Version returns the current config file format version
func (d config) Version() string {
st := structs.New(*d.data)
f, ok := st.FieldOk("Version")
if !ok {
return ""
}
val := f.Value()
ver, ok := val.(string)
if ok {
return ver
}
return ""
}
// String converts JSON config to printable string
func (d config) String() string {
configBytes, _ := json.MarshalIndent(*d.data, "", "\t")
return string(configBytes)
}
// Save writes config data in JSON format to a file.
func (d config) Save(filename string) (err error) {
d.lock.Lock()
defer d.lock.Unlock()
jsonData, err := json.MarshalIndent(d.data, "", "\t")
if err != nil {
return iodine.New(err, nil)
}
file, err := atomic.FileCreate(filename)
if err != nil {
return iodine.New(err, nil)
}
if runtime.GOOS == "windows" {
jsonData = []byte(strings.Replace(string(jsonData), "\n", "\r\n", -1))
}
_, err = file.Write(jsonData)
if err != nil {
return iodine.New(err, nil)
}
if err := file.Close(); err != nil {
return iodine.New(err, nil)
}
return nil
}
// Load - loads JSON config from file and merge with currently set values
func (d *config) Load(filename string) (err error) {
(*d).lock.Lock()
defer (*d).lock.Unlock()
_, err = os.Stat(filename)
if err != nil {
return iodine.New(err, nil)
}
fileData, err := ioutil.ReadFile(filename)
if err != nil {
return iodine.New(err, nil)
}
if runtime.GOOS == "windows" {
fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
}
err = json.Unmarshal(fileData, (*d).data)
if err != nil {
return iodine.New(err, nil)
}
err = CheckData(*(*d).data)
if err != nil {
return iodine.New(err, nil)
}
st := structs.New(*(*d).data)
f, ok := st.FieldOk("Version")
if !ok {
return iodine.New(fmt.Errorf("Argument struct [%s] does not contain field \"Version\".", st.Name()), nil)
}
if (*d).Version() != f.Value() {
return iodine.New(errors.New("Version mismatch"), nil)
}
return nil
}
// Data - grab internal data map for reading
func (d config) Data() interface{} {
return *d.data
}
//Diff - list fields that are in A but not in B
func (d config) Diff(c Config) (fields []structs.Field, err error) {
err = CheckData(c.Data())
if err != nil {
return []structs.Field{}, iodine.New(err, nil)
}
currFields := structs.Fields(d.Data())
newFields := structs.Fields(c.Data())
found := false
for _, currField := range currFields {
found = false
for _, newField := range newFields {
if reflect.DeepEqual(currField.Name(), newField.Name()) {
found = true
}
}
if !found {
fields = append(fields, *currField)
}
}
return fields, nil
}
//DeepDiff - list fields in A that are missing or not equal to fields in B
func (d config) DeepDiff(c Config) (fields []structs.Field, err error) {
err = CheckData(c.Data())
if err != nil {
return []structs.Field{}, iodine.New(err, nil)
}
currFields := structs.Fields(d.Data())
newFields := structs.Fields(c.Data())
found := false
for _, currField := range currFields {
found = false
for _, newField := range newFields {
if reflect.DeepEqual(currField.Value(), newField.Value()) {
found = true
}
}
if !found {
fields = append(fields, *currField)
}
}
return fields, nil
}