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145 lines
2.9 KiB

package config
import (
"context"
"errors"
"fmt"
"sync"
"sync/atomic"
)
func Must(providers ...interface{}) *Client {
client, err := New(providers...)
if err != nil {
panic(err)
}
return client
}
func New(providers ...interface{}) (*Client, error) {
client := &Client{
providers: make([]Provider, len(providers)),
}
for idx, prov := range providers {
switch current := prov.(type) {
case Provider:
client.providers[idx] = current
case Factory:
client.providers[idx] = &provider{
factory: func(ctx context.Context) (Provider, error) {
return current(ctx, client)
},
}
default:
return nil, fmt.Errorf("provier[%d]: %w %T", idx, ErrUnknowType, prov)
}
}
return client, nil
}
type provider struct {
mu sync.Mutex
done uint32
provider Provider
factory func(ctx context.Context) (Provider, error)
}
func (p *provider) init(ctx context.Context) error {
if atomic.LoadUint32(&p.done) == 0 {
if !p.mu.TryLock() {
return fmt.Errorf("%w", ErrInitFactory)
}
defer atomic.StoreUint32(&p.done, 1)
defer p.mu.Unlock()
var err error
if p.provider, err = p.factory(ctx); err != nil {
return fmt.Errorf("init provider factory:%w", err)
}
}
return nil
}
func (p *provider) Watch(ctx context.Context, callback WatchCallback, path ...string) error {
if err := p.init(ctx); err != nil {
return fmt.Errorf("init read:%w", err)
}
watch, ok := p.provider.(WatchProvider)
if !ok {
return nil
}
if err := watch.Watch(ctx, callback, path...); err != nil {
return fmt.Errorf("factory provider: %w", err)
}
return nil
}
func (p *provider) Value(ctx context.Context, path ...string) (Value, error) {
if err := p.init(ctx); err != nil {
return nil, fmt.Errorf("init read:%w", err)
}
variable, err := p.provider.Value(ctx, path...)
if err != nil {
return nil, fmt.Errorf("factory provider: %w", err)
}
return variable, nil
}
type Client struct {
providers []Provider
}
func (c *Client) Name() string {
return "client"
}
// Value get value by name.
func (c *Client) Value(ctx context.Context, path ...string) (Value, error) {
var (
value Value
err error
)
for _, provider := range c.providers {
value, err = provider.Value(ctx, path...)
if err == nil || !(errors.Is(err, ErrValueNotFound) || errors.Is(err, ErrInitFactory)) {
break
}
}
if err != nil {
return value, fmt.Errorf("client failed get value: %w", err)
}
return value, nil
}
func (c *Client) Watch(ctx context.Context, callback WatchCallback, path ...string) error {
for idx, prov := range c.providers {
provider, ok := prov.(WatchProvider)
if !ok {
continue
}
err := provider.Watch(ctx, callback, path...)
if err != nil {
if errors.Is(err, ErrValueNotFound) || errors.Is(err, ErrInitFactory) {
continue
}
return fmt.Errorf("client: failed watch by provider[%d]: %w", idx, err)
}
}
return nil
}