Method reportMetadata

agent/agent.go:607–818

(ctx context.Context, aAPI proto.DRPCAgentClient28)

}

func (a *agent) reportMetadata(ctx context.Context, aAPI proto.DRPCAgentClient28) error {
	tickerDone := make(chan struct{})
	collectDone := make(chan struct{})
	ctx, cancel := context.WithCancel(ctx)
	defer func() {
		cancel()
		<-collectDone
		<-tickerDone
	}()

	var (
		logger          = a.logger.Named("metadata")
		report          = make(chan struct{}, 1)
		collect         = make(chan struct{}, 1)
		metadataResults = make(chan metadataResultAndKey, 1)
	)

	// Set up collect and report as a single ticker with two channels,
	// this is to allow collection and reporting to be triggered
	// independently of each other.
	go func() {
		t := time.NewTicker(a.reportMetadataInterval)
		defer func() {
			t.Stop()
			close(report)
			close(collect)
			close(tickerDone)
		}()
		wake := func(c chan<- struct{}) {
			select {
			case c <- struct{}{}:
			default:
			}
		}
		wake(collect) // Start immediately.

		for {
			select {
			case <-ctx.Done():
				return
			case <-t.C:
				wake(report)
				wake(collect)
			}
		}
	}()

	go func() {
		defer close(collectDone)

		var (
			// We use a custom singleflight that immediately returns if there is already
			// a goroutine running for a given key. This is to prevent a build-up of
			// goroutines waiting on Do when the script takes many multiples of
			// baseInterval to run.
			flight            = trySingleflight{m: map[string]struct{}{}}
			lastCollectedAtMu sync.RWMutex
			lastCollectedAts  = make(map[string]time.Time)