237 lines
5.8 KiB
Go
237 lines
5.8 KiB
Go
/*
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* Quick - Quick key value store for config files and persistent state files
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*
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* Quick (C) 2015, 2016, 2017 MinIO, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package quick
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import (
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"encoding/json"
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"fmt"
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"io/ioutil"
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"os"
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"reflect"
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"sync"
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etcd "github.com/coreos/etcd/clientv3"
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"github.com/fatih/structs"
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"github.com/minio/minio/pkg/safe"
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)
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// Config - generic config interface functions
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type Config interface {
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String() string
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Version() string
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Save(string) error
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Load(string) error
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Data() interface{}
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Diff(Config) ([]structs.Field, error)
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DeepDiff(Config) ([]structs.Field, error)
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}
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// config - implements quick.Config interface
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type config struct {
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data interface{}
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clnt *etcd.Client
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lock *sync.RWMutex
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}
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// Version returns the current config file format version
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func (d config) Version() string {
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st := structs.New(d.data)
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f := st.Field("Version")
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return f.Value().(string)
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}
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// String converts JSON config to printable string
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func (d config) String() string {
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configBytes, _ := json.MarshalIndent(d.data, "", "\t")
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return string(configBytes)
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}
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// Save writes config data to a file. Data format
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// is selected based on file extension or JSON if
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// not provided.
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func (d config) Save(filename string) error {
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d.lock.Lock()
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defer d.lock.Unlock()
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if d.clnt != nil {
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return saveFileConfigEtcd(filename, d.clnt, d.data)
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}
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// Backup if given file exists
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oldData, err := ioutil.ReadFile(filename)
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if err != nil {
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// Ignore if file does not exist.
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if !os.IsNotExist(err) {
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return err
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}
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} else {
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// Save read data to the backup file.
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backupFilename := filename + ".old"
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if err = writeFile(backupFilename, oldData); err != nil {
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return err
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}
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}
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// Save data.
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return saveFileConfig(filename, d.data)
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}
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// Load - loads config from file and merge with currently set values
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// File content format is guessed from the file name extension, if not
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// available, consider that we have JSON.
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func (d config) Load(filename string) error {
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d.lock.Lock()
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defer d.lock.Unlock()
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if d.clnt != nil {
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return loadFileConfigEtcd(filename, d.clnt, d.data)
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}
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return loadFileConfig(filename, d.data)
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}
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// Data - grab internal data map for reading
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func (d config) Data() interface{} {
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return d.data
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}
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// Diff - list fields that are in A but not in B
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func (d config) Diff(c Config) ([]structs.Field, error) {
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var fields []structs.Field
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currFields := structs.Fields(d.Data())
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newFields := structs.Fields(c.Data())
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var found bool
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for _, currField := range currFields {
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found = false
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for _, newField := range newFields {
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if reflect.DeepEqual(currField.Name(), newField.Name()) {
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found = true
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}
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}
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if !found {
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fields = append(fields, *currField)
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}
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}
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return fields, nil
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}
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// DeepDiff - list fields in A that are missing or not equal to fields in B
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func (d config) DeepDiff(c Config) ([]structs.Field, error) {
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var fields []structs.Field
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currFields := structs.Fields(d.Data())
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newFields := structs.Fields(c.Data())
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var found bool
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for _, currField := range currFields {
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found = false
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for _, newField := range newFields {
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if reflect.DeepEqual(currField.Value(), newField.Value()) {
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found = true
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}
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}
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if !found {
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fields = append(fields, *currField)
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}
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}
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return fields, nil
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}
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// CheckData - checks the validity of config data. Data should be of
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// type struct and contain a string type field called "Version".
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func CheckData(data interface{}) error {
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if !structs.IsStruct(data) {
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return fmt.Errorf("interface must be struct type")
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}
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st := structs.New(data)
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f, ok := st.FieldOk("Version")
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if !ok {
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return fmt.Errorf("struct ‘%s’ must have field ‘Version’", st.Name())
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}
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if f.Kind() != reflect.String {
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return fmt.Errorf("‘Version’ field in struct ‘%s’ must be a string type", st.Name())
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}
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return nil
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}
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// writeFile writes data to a file named by filename.
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// If the file does not exist, writeFile creates it;
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// otherwise writeFile truncates it before writing.
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func writeFile(filename string, data []byte) error {
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safeFile, err := safe.CreateFile(filename)
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if err != nil {
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return err
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}
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_, err = safeFile.Write(data)
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if err != nil {
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return err
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}
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return safeFile.Close()
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}
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// GetVersion - extracts the version information.
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func GetVersion(filename string, clnt *etcd.Client) (version string, err error) {
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var qc Config
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qc, err = LoadConfig(filename, clnt, &struct {
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Version string
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}{})
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if err != nil {
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return "", err
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}
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return qc.Version(), nil
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}
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// LoadConfig - loads json config from filename for the a given struct data
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func LoadConfig(filename string, clnt *etcd.Client, data interface{}) (qc Config, err error) {
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qc, err = NewConfig(data, clnt)
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if err != nil {
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return nil, err
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}
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return qc, qc.Load(filename)
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}
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// SaveConfig - saves given configuration data into given file as JSON.
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func SaveConfig(data interface{}, filename string, clnt *etcd.Client) (err error) {
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if err = CheckData(data); err != nil {
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return err
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}
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var qc Config
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qc, err = NewConfig(data, clnt)
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if err != nil {
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return err
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}
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return qc.Save(filename)
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}
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// NewConfig loads config from etcd client if provided, otherwise loads from a local filename.
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// fails when all else fails.
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func NewConfig(data interface{}, clnt *etcd.Client) (cfg Config, err error) {
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if err := CheckData(data); err != nil {
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return nil, err
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}
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d := new(config)
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d.data = data
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d.clnt = clnt
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d.lock = new(sync.RWMutex)
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return d, nil
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}
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