fix(envd): port scanner ScanAndBroadcast uses time.Sleep instead of select+ticker, delaying shutdown

[AdaAibaby]

Summary

ScanAndBroadcast() in the envd port scanner uses a bare time.Sleep to pace scans. Because Destroy() closes the scanExit channel but the goroutine checks it before sleeping (not after), a Destroy() call that arrives during the sleep is not noticed until the sleep completes.

Location: packages/envd/internal/port/scan.go:44

func (s *Scanner) ScanAndBroadcast() {
    for {
        processes, _ := net.Connections("tcp")
        for _, sub := range s.subs.Items() {
            sub.Signal(processes)
        }
        select {
        case <-s.scanExit:
            return
        default:
            time.Sleep(s.period)  // ← shutdown waits up to `period` here
        }
    }
}

Root cause

The select only tests scanExit at the top of each iteration, before the sleep. Once time.Sleep starts, a concurrent Destroy() closes scanExit but the goroutine doesn't wake up — it sleeps the full period before looping back and seeing the closed channel.

If period is long (the default is not specified here, but envd calls NewScanner(portScannerInterval) — if that's on the order of seconds) shutdown is delayed unnecessarily.

Proposed fix

Replace the time.Sleep with a time.After inside the select so Destroy() can interrupt the sleep immediately:

func (s *Scanner) ScanAndBroadcast() {
    for {
        processes, _ := net.Connections("tcp")
        for _, sub := range s.subs.Items() {
            sub.Signal(processes)
        }
        select {
        case <-s.scanExit:
            return
        case <-time.After(s.period):
        }
    }
}

Or use a time.Ticker (more efficient — avoids a new timer allocation per iteration):

func (s *Scanner) ScanAndBroadcast() {
    ticker := time.NewTicker(s.period)
    defer ticker.Stop()
    for {
        processes, _ := net.Connections("tcp")
        for _, sub := range s.subs.Items() {
            sub.Signal(processes)
        }
        select {
        case <-s.scanExit:
            return
        case <-ticker.C:
        }
    }
}

Impact

With the current code, every envd shutdown is delayed by up to portScannerInterval waiting for the port scanner goroutine to wake from its sleep and notice the exit signal. The fix makes shutdown instantaneous for this goroutine.

[arkamar]

Fixed in PR #3374