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watcher.go
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watcher.go
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package config
import (
"context"
"time"
stime "github.com/alexfalkowski/go-service/time"
"github.com/radovskyb/watcher"
"go.uber.org/fx"
"go.uber.org/zap"
)
// WaitTime for shutting down.
type WaitTime time.Duration
// NewWaitTime for shutting down.
func NewWaitTime() WaitTime {
return WaitTime(stime.RandomWaitTime())
}
// WatchParams for config.
type WatchParams struct {
fx.In
Lifecycle fx.Lifecycle
Shutdowner fx.Shutdowner
Logger *zap.Logger
WaitTime WaitTime
Config Configurator
}
// Watch the configuration. If it changes terminate the application.
func Watch(params WatchParams) error {
watcher := NewWatcher(params)
params.Lifecycle.Append(fx.Hook{
OnStart: func(context.Context) error {
return watcher.Start()
},
OnStop: func(ctx context.Context) error {
return watcher.Stop()
},
})
return nil
}
// NewWatcher of config changes.
func NewWatcher(params WatchParams) *Watcher {
return &Watcher{sh: params.Shutdowner, logger: params.Logger, waitTime: time.Duration(params.WaitTime), cfg: params.Config}
}
// Watcher of config changes.
type Watcher struct {
poll *watcher.Watcher
sh fx.Shutdowner
logger *zap.Logger
waitTime time.Duration
cfg Configurator
}
// Start watching.
func (w *Watcher) Start() error {
poll := watcher.New()
poll.FilterOps(watcher.Write)
w.poll = poll
go w.pollWatch()
if err := poll.Add(File()); err != nil {
return err
}
go poll.Start(time.Second)
return nil
}
// Stop watching.
func (w *Watcher) Stop() error {
w.poll.Close()
return nil
}
func (w *Watcher) pollWatch() {
for {
select {
case _ = <-w.poll.Event:
_ = w.shutdown()
case err := <-w.poll.Error:
w.logger.Error("watching configuration", zap.Error(err))
case <-w.poll.Closed:
return
}
}
}
func (w *Watcher) shutdown() error {
w.logger.Info("configuration has been modified", zap.Duration("duration", w.waitTime))
time.Sleep(w.waitTime)
return w.sh.Shutdown()
}