runtime: use methods for timer

Continuing conversion from C to Go, change timer API to use methods.

[This is one CL in a refactoring stack making very small changes
in each step, so that any subtle bugs that we miss can be more
easily pinpointed to a small change.]

Change-Id: I4cb88a366993a77aa4fad739793a7db7213cc38c
Reviewed-on: https://go-review.googlesource.com/c/go/+/564131
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/runtime/netpoll.go

@@ -399,14 +399,14 @@ func poll_runtime_pollSetDeadline(pd *pollDesc, d int64, mode int) {
 			// if they differ the descriptor was reused or timers were reset.
 			pd.rt.arg = pd.makeArg()
 			pd.rt.seq = pd.rseq
-			resettimer(&pd.rt, pd.rd)
+			pd.rt.reset(pd.rd)
 		}
 	} else if pd.rd != rd0 || combo != combo0 {
 		pd.rseq++ // invalidate current timers
 		if pd.rd > 0 {
-			modtimer(&pd.rt, pd.rd, 0, rtf, pd.makeArg(), pd.rseq)
+			pd.rt.modify(pd.rd, 0, rtf, pd.makeArg(), pd.rseq)
 		} else {
-			deltimer(&pd.rt)
+			pd.rt.stop()
 			pd.rt.f = nil
 		}
 	}
@@ -415,14 +415,14 @@ func poll_runtime_pollSetDeadline(pd *pollDesc, d int64, mode int) {
 			pd.wt.f = netpollWriteDeadline
 			pd.wt.arg = pd.makeArg()
 			pd.wt.seq = pd.wseq
-			resettimer(&pd.wt, pd.wd)
+			pd.wt.reset(pd.wd)
 		}
 	} else if pd.wd != wd0 || combo != combo0 {
 		pd.wseq++ // invalidate current timers
 		if pd.wd > 0 && !combo {
-			modtimer(&pd.wt, pd.wd, 0, netpollWriteDeadline, pd.makeArg(), pd.wseq)
+			pd.wt.modify(pd.wd, 0, netpollWriteDeadline, pd.makeArg(), pd.wseq)
 		} else {
-			deltimer(&pd.wt)
+			pd.wt.stop()
 			pd.wt.f = nil
 		}
 	}
@@ -461,11 +461,11 @@ func poll_runtime_pollUnblock(pd *pollDesc) {
 	rg = netpollunblock(pd, 'r', false, &delta)
 	wg = netpollunblock(pd, 'w', false, &delta)
 	if pd.rt.f != nil {
-		deltimer(&pd.rt)
+		pd.rt.stop()
 		pd.rt.f = nil
 	}
 	if pd.wt.f != nil {
-		deltimer(&pd.wt)
+		pd.wt.stop()
 		pd.wt.f = nil
 	}
 	unlock(&pd.lock)

src/runtime/time.go

@@ -190,7 +190,7 @@ func timeSleep(ns int64) {
 // timer function, goroutineReady, before the goroutine has been parked.
 func resetForSleep(gp *g, ut unsafe.Pointer) bool {
 	t := (*timer)(ut)
-	resettimer(t, t.nextWhen)
+	t.reset(t.nextWhen)
 	return true
 }
 
@@ -204,7 +204,7 @@ func startTimer(t *timer) {
 	if t.state.Load() != 0 {
 		throw("startTimer called with initialized timer")
 	}
-	resettimer(t, t.when)
+	t.reset(t.when)
 }
 
 // stopTimer stops a timer.
@@ -212,7 +212,7 @@ func startTimer(t *timer) {
 //
 //go:linkname stopTimer time.stopTimer
 func stopTimer(t *timer) bool {
-	return deltimer(t)
+	return t.stop()
 }
 
 // resetTimer resets an inactive timer, adding it to the heap.
@@ -224,14 +224,14 @@ func resetTimer(t *timer, when int64) bool {
 	if raceenabled {
 		racerelease(unsafe.Pointer(t))
 	}
-	return resettimer(t, when)
+	return t.reset(when)
 }
 
 // modTimer modifies an existing timer.
 //
 //go:linkname modTimer time.modTimer
 func modTimer(t *timer, when, period int64) {
-	modtimer(t, when, period, t.f, t.arg, t.seq)
+	t.modify(when, period, t.f, t.arg, t.seq)
 }
 
 // Go runtime.
@@ -263,11 +263,11 @@ func doaddtimer(pp *p, t *timer) {
 	pp.numTimers.Add(1)
 }
 
-// deltimer deletes the timer t. It may be on some other P, so we can't
-// actually remove it from the timers heap. We can only mark it as deleted.
+// stop deletes the timer t. It may be on some other P, so we can't
+// actually remove it from the timers heap. We can only mark it as stopped.
 // It will be removed in due course by the P whose heap it is on.
-// Reports whether the timer was removed before it was run.
-func deltimer(t *timer) bool {
+// Reports whether the timer was stopped before it was run.
+func (t *timer) stop() bool {
 	state, mp := t.lock()
 	if state&timerHeaped != 0 && (state&timerNextWhen == 0 || t.nextWhen != 0) {
 		// Timer pending: stop it.
@@ -310,10 +310,10 @@ func dodeltimer0(pp *p) {
 	}
 }
 
-// modtimer modifies an existing timer.
+// modify modifies an existing timer.
 // This is called by the netpoll code or time.Ticker.Reset or time.Timer.Reset.
 // Reports whether the timer was modified before it was run.
-func modtimer(t *timer, when, period int64, f func(any, uintptr), arg any, seq uintptr) bool {
+func (t *timer) modify(when, period int64, f func(any, uintptr), arg any, seq uintptr) bool {
 	if when <= 0 {
 		throw("timer when must be positive")
 	}
@@ -377,11 +377,11 @@ func modtimer(t *timer, when, period int64, f func(any, uintptr), arg any, seq u
 	return pending
 }
 
-// resettimer resets the time when a timer should fire.
+// reset resets the time when a timer should fire.
 // If used for an inactive timer, the timer will become active.
 // Reports whether the timer was active and was stopped.
-func resettimer(t *timer, when int64) bool {
-	return modtimer(t, when, t.period, t.f, t.arg, t.seq)
+func (t *timer) reset(when int64) bool {
+	return t.modify(when, t.period, t.f, t.arg, t.seq)
 }
 
 // cleantimers cleans up the head of the timer queue. This speeds up