95 lines
1.9 KiB
Go
95 lines
1.9 KiB
Go
package precreator
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import (
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"log"
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"os"
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"sync"
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"time"
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)
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// Service manages the shard precreation service.
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type Service struct {
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checkInterval time.Duration
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advancePeriod time.Duration
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Logger *log.Logger
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done chan struct{}
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wg sync.WaitGroup
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MetaClient interface {
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PrecreateShardGroups(now, cutoff time.Time) error
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}
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}
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// NewService returns an instance of the precreation service.
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func NewService(c Config) (*Service, error) {
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s := Service{
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checkInterval: time.Duration(c.CheckInterval),
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advancePeriod: time.Duration(c.AdvancePeriod),
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Logger: log.New(os.Stderr, "[shard-precreation] ", log.LstdFlags),
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}
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return &s, nil
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}
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// SetLogger sets the internal logger to the logger passed in.
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func (s *Service) SetLogger(l *log.Logger) {
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s.Logger = l
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}
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// Open starts the precreation service.
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func (s *Service) Open() error {
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if s.done != nil {
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return nil
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}
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s.Logger.Printf("Starting precreation service with check interval of %s, advance period of %s",
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s.checkInterval, s.advancePeriod)
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s.done = make(chan struct{})
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s.wg.Add(1)
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go s.runPrecreation()
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return nil
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}
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// Close stops the precreation service.
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func (s *Service) Close() error {
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if s.done == nil {
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return nil
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}
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close(s.done)
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s.wg.Wait()
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s.done = nil
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return nil
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}
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// runPrecreation continually checks if resources need precreation.
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func (s *Service) runPrecreation() {
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defer s.wg.Done()
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for {
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select {
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case <-time.After(s.checkInterval):
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if err := s.precreate(time.Now().UTC()); err != nil {
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s.Logger.Printf("failed to precreate shards: %s", err.Error())
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}
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case <-s.done:
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s.Logger.Println("Precreation service terminating")
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return
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}
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}
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}
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// precreate performs actual resource precreation.
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func (s *Service) precreate(now time.Time) error {
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cutoff := now.Add(s.advancePeriod).UTC()
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if err := s.MetaClient.PrecreateShardGroups(now, cutoff); err != nil {
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return err
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}
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return nil
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}
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