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dynconfig.go
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dynconfig.go
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/*
* Copyright 2020 The Dragonfly Authors
*
* 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 dynconfig
import (
"errors"
"time"
"github.com/mitchellh/mapstructure"
)
type SourceType string
const (
// LocalSourceType represents read configuration from local file
LocalSourceType = "local"
// ManagerSourceType represents pulling configuration from manager
ManagerSourceType = "manager"
)
const (
defaultCacheKey = "dynconfig"
)
type strategy interface {
Unmarshal(rawVal interface{}) error
}
type Dynconfig struct {
sourceType SourceType
managerClient ManagerClient
localConfigPath string
cachePath string
expire time.Duration
strategy strategy
}
// Option is a functional option for configuring the dynconfig
type Option func(d *Dynconfig) error
// WithManagerClient set the manager client
func WithManagerClient(c ManagerClient) Option {
return func(d *Dynconfig) error {
d.managerClient = c
return nil
}
}
// WithLocalConfigPath set the file path
func WithLocalConfigPath(p string) Option {
return func(d *Dynconfig) error {
d.localConfigPath = p
return nil
}
}
// WithCachePath set the cache file path
func WithCachePath(p string) Option {
return func(d *Dynconfig) error {
d.cachePath = p
return nil
}
}
// WithExpireTime set the expire time for cache
func WithExpireTime(e time.Duration) Option {
return func(d *Dynconfig) error {
d.expire = e
return nil
}
}
// New returns a new dynconfig instance
func New(sourceType SourceType, options ...Option) (*Dynconfig, error) {
d, err := NewDynconfigWithOptions(sourceType, options...)
if err != nil {
return nil, err
}
if err := d.validate(); err != nil {
return nil, err
}
switch sourceType {
case ManagerSourceType:
d.strategy, err = newDynconfigManager(d.expire, d.cachePath, d.managerClient)
if err != nil {
return nil, err
}
case LocalSourceType:
d.strategy, err = newDynconfigLocal(d.localConfigPath)
if err != nil {
return nil, err
}
default:
return nil, errors.New("unknown source type")
}
return d, nil
}
// NewDynconfigWithOptions constructs a new instance of a dynconfig with additional options.
func NewDynconfigWithOptions(sourceType SourceType, options ...Option) (*Dynconfig, error) {
d := &Dynconfig{
sourceType: sourceType,
}
for _, opt := range options {
if err := opt(d); err != nil {
return nil, err
}
}
return d, nil
}
// validate parameters
func (d *Dynconfig) validate() error {
if d.sourceType == ManagerSourceType {
if d.managerClient == nil {
return errors.New("missing parameter ManagerClient, use method WithManagerClient to assign")
}
if d.cachePath == "" {
return errors.New("missing parameter CachePath, use method WithCachePath to assign")
}
if d.expire == 0 {
return errors.New("missing parameter Expire, use method WithExpireTime to assign")
}
}
if d.sourceType == LocalSourceType && d.localConfigPath == "" {
return errors.New("missing parameter LocalConfigPath, use method WithLocalConfigPath to assign")
}
return nil
}
// Unmarshal unmarshals the config into a Struct. Make sure that the tags
// on the fields of the structure are properly set.
func (d *Dynconfig) Unmarshal(rawVal interface{}) error {
return d.strategy.Unmarshal(rawVal)
}
// A DecoderConfigOption can be passed to dynconfig Unmarshal to configure
// mapstructure.DecoderConfig options
type DecoderConfigOption func(*mapstructure.DecoderConfig)
// defaultDecoderConfig returns default mapstructure.DecoderConfig with support
// of time.Duration values & string slices
func defaultDecoderConfig(output interface{}) *mapstructure.DecoderConfig {
c := &mapstructure.DecoderConfig{
Metadata: nil,
Result: output,
WeaklyTypedInput: true,
DecodeHook: mapstructure.ComposeDecodeHookFunc(
mapstructure.StringToTimeDurationHookFunc(),
mapstructure.StringToSliceHookFunc(","),
),
}
return c
}
// A wrapper around mapstructure.Decode that mimics the WeakDecode functionality
func decode(input interface{}, config *mapstructure.DecoderConfig) error {
decoder, err := mapstructure.NewDecoder(config)
if err != nil {
return err
}
return decoder.Decode(input)
}