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package watcher
import (
"context"
"fmt"
"log"
"time"
"gitoa.ru/go-4devs/config"
)
var (
_ config.Provider = (*Provider)(nil)
_ config.WatchProvider = (*Provider)(nil)
)
func New(duration time.Duration, provider config.Provider, opts ...Option) *Provider {
prov := &Provider{
Provider: provider,
ticker: time.NewTicker(duration),
logger: func(_ context.Context, msg string) {
log.Print(msg)
},
}
for _, opt := range opts {
opt(prov)
}
return prov
}
func WithLogger(l func(context.Context, string)) Option {
return func(p *Provider) {
p.logger = l
}
}
type Option func(*Provider)
type Provider struct {
config.Provider
ticker *time.Ticker
logger func(context.Context, string)
}
func (p *Provider) Watch(ctx context.Context, key config.Key, callback config.WatchCallback) error {
oldVar, err := p.Provider.Read(ctx, key)
if err != nil {
return fmt.Errorf("failed watch variable: %w", err)
}
go func() {
for {
select {
case <-p.ticker.C:
newVar, err := p.Provider.Read(ctx, key)
if err != nil {
p.logger(ctx, err.Error())
} else if !newVar.IsEquals(oldVar) {
callback(ctx, oldVar, newVar)
oldVar = newVar
}
case <-ctx.Done():
return
}
}
}()
return nil
}