minio/pkg/quick/quick.go
Bala FA d4ca2ee1a3 pkg/quick: add Save() function and other enhancements. (#3951)
* Add a new function Save() which saves given configuration into given file.
* Simplify Load() function.
* Remove unused CheckVersion().
* CheckData() is a private function now.
* quick_test.go is part of quick package now.
* minio server uses top level quick.Load() and quick.Save() functions.
2017-03-22 10:23:25 -07:00

217 lines
5.1 KiB
Go
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/*
* Quick - Quick key value store for config files and persistent state files
*
* Quick (C) 2015, 2016, 2017 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"
"fmt"
"io/ioutil"
"os"
"reflect"
"sync"
"github.com/fatih/structs"
"github.com/minio/minio/pkg/safe"
)
// 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
}
// Version returns the current config file format version
func (d config) Version() string {
st := structs.New(d.data)
f := st.Field("Version")
return f.Value().(string)
}
// 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 to a file. Data format
// is selected based on file extension or JSON if
// not provided.
func (d config) Save(filename string) error {
d.lock.Lock()
defer d.lock.Unlock()
// Backup if given file exists
oldData, err := ioutil.ReadFile(filename)
if err != nil {
// Ignore if file does not exist.
if !os.IsNotExist(err) {
return err
}
} else {
// Save read data to the backup file.
backupFilename := filename + ".old"
if err = writeFile(backupFilename, oldData); err != nil {
return err
}
}
// Save data.
return saveFileConfig(filename, d.data)
}
// Load - loads config from file and merge with currently set values
// File content format is guessed from the file name extension, if not
// available, consider that we have JSON.
func (d config) Load(filename string) error {
d.lock.Lock()
defer d.lock.Unlock()
if err := loadFileConfig(filename, d.data); err != nil {
return err
}
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) ([]structs.Field, error) {
var fields []structs.Field
currFields := structs.Fields(d.Data())
newFields := structs.Fields(c.Data())
var found bool
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) ([]structs.Field, error) {
var fields []structs.Field
currFields := structs.Fields(d.Data())
newFields := structs.Fields(c.Data())
var found bool
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
}
// checkData - checks the validity of config data. Data should be of
// type struct and contain a string type field called "Version".
func checkData(data interface{}) error {
if !structs.IsStruct(data) {
return fmt.Errorf("interface must be struct type")
}
st := structs.New(data)
f, ok := st.FieldOk("Version")
if !ok {
return fmt.Errorf("struct %s must have field Version", st.Name())
}
if f.Kind() != reflect.String {
return fmt.Errorf("Version field in struct %s must be a string type", st.Name())
}
return nil
}
// writeFile writes data to a file named by filename.
// If the file does not exist, writeFile creates it;
// otherwise writeFile truncates it before writing.
func writeFile(filename string, data []byte) error {
safeFile, err := safe.CreateFile(filename)
if err != nil {
return err
}
_, err = safeFile.Write(data)
if err != nil {
return err
}
return safeFile.Close()
}
// New - instantiate a new config
func New(data interface{}) (Config, error) {
if err := checkData(data); err != nil {
return nil, err
}
d := new(config)
d.data = data
d.lock = new(sync.RWMutex)
return d, nil
}
// Load - loads json config from filename for the a given struct data
func Load(filename string, data interface{}) (qc Config, err error) {
if qc, err = New(data); err == nil {
err = qc.Load(filename)
}
return qc, err
}
// Save - saves given configuration data into given file as JSON.
func Save(filename string, data interface{}) (err error) {
var qc Config
if qc, err = New(data); err == nil {
err = qc.Save(filename)
}
return err
}