diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp/timer.go')
| -rw-r--r-- | pkg/tcpip/transport/tcp/timer.go | 51 |
1 files changed, 26 insertions, 25 deletions
diff --git a/pkg/tcpip/transport/tcp/timer.go b/pkg/tcpip/transport/tcp/timer.go index 38a335840..5645c772e 100644 --- a/pkg/tcpip/transport/tcp/timer.go +++ b/pkg/tcpip/transport/tcp/timer.go @@ -15,21 +15,29 @@ package tcp import ( + "math" "time" "gvisor.dev/gvisor/pkg/sleep" + "gvisor.dev/gvisor/pkg/tcpip" ) type timerState int const ( + // The timer is disabled. timerStateDisabled timerState = iota + // The timer is enabled, but the clock timer may be set to an earlier + // expiration time due to a previous orphaned state. timerStateEnabled + // The timer is disabled, but the clock timer is enabled, which means that + // it will cause a spurious wakeup unless the timer is enabled before the + // clock timer fires. timerStateOrphaned ) // timer is a timer implementation that reduces the interactions with the -// runtime timer infrastructure by letting timers run (and potentially +// clock timer infrastructure by letting timers run (and potentially // eventually expire) even if they are stopped. It makes it cheaper to // disable/reenable timers at the expense of spurious wakes. This is useful for // cases when the same timer is disabled/reenabled repeatedly with relatively @@ -39,44 +47,37 @@ const ( // (currently at least 200ms), and get disabled when acks are received, and // reenabled when new pending segments are sent. // -// It is advantageous to avoid interacting with the runtime because it acquires +// It is advantageous to avoid interacting with the clock because it acquires // a global mutex and performs O(log n) operations, where n is the global number // of timers, whenever a timer is enabled or disabled, and may make a syscall. // // This struct is thread-compatible. type timer struct { - // state is the current state of the timer, it can be one of the - // following values: - // disabled - the timer is disabled. - // orphaned - the timer is disabled, but the runtime timer is - // enabled, which means that it will evetually cause a - // spurious wake (unless it gets enabled again before - // then). - // enabled - the timer is enabled, but the runtime timer may be set - // to an earlier expiration time due to a previous - // orphaned state. state timerState + clock tcpip.Clock + // target is the expiration time of the current timer. It is only // meaningful in the enabled state. - target time.Time + target tcpip.MonotonicTime - // runtimeTarget is the expiration time of the runtime timer. It is + // clockTarget is the expiration time of the clock timer. It is // meaningful in the enabled and orphaned states. - runtimeTarget time.Time + clockTarget tcpip.MonotonicTime - // timer is the runtime timer used to wait on. - timer *time.Timer + // timer is the clock timer used to wait on. + timer tcpip.Timer } // init initializes the timer. Once it expires, it the given waker will be // asserted. -func (t *timer) init(w *sleep.Waker) { +func (t *timer) init(clock tcpip.Clock, w *sleep.Waker) { t.state = timerStateDisabled + t.clock = clock - // Initialize a runtime timer that will assert the waker, then + // Initialize a clock timer that will assert the waker, then // immediately stop it. - t.timer = time.AfterFunc(time.Hour, func() { + t.timer = t.clock.AfterFunc(math.MaxInt64, func() { w.Assert() }) t.timer.Stop() @@ -106,9 +107,9 @@ func (t *timer) checkExpiration() bool { // The timer is enabled, but it may have expired early. Check if that's // the case, and if so, reset the runtime timer to the correct time. - now := time.Now() + now := t.clock.NowMonotonic() if now.Before(t.target) { - t.runtimeTarget = t.target + t.clockTarget = t.target t.timer.Reset(t.target.Sub(now)) return false } @@ -134,11 +135,11 @@ func (t *timer) enabled() bool { // enable enables the timer, programming the runtime timer if necessary. func (t *timer) enable(d time.Duration) { - t.target = time.Now().Add(d) + t.target = t.clock.NowMonotonic().Add(d) // Check if we need to set the runtime timer. - if t.state == timerStateDisabled || t.target.Before(t.runtimeTarget) { - t.runtimeTarget = t.target + if t.state == timerStateDisabled || t.target.Before(t.clockTarget) { + t.clockTarget = t.target t.timer.Reset(d) } |