1 files changed, 32 insertions, 156 deletions

diff --git a/libgo/go/time/tick.go b/libgo/go/time/tick.go
index 92f9eb893e4..4440c2207b3 100644
--- a/libgo/go/time/tick.go
+++ b/libgo/go/time/tick.go
@@ -4,174 +4,50 @@
 
 package time
 
-import (
-	"errors"
-	"sync"
-)
+import "errors"
 
 // A Ticker holds a synchronous channel that delivers `ticks' of a clock
 // at intervals.
 type Ticker struct {
-	C        <-chan int64 // The channel on which the ticks are delivered.
-	c        chan<- int64 // The same channel, but the end we use.
-	ns       int64
-	shutdown chan bool // Buffered channel used to signal shutdown.
-	nextTick int64
-	next     *Ticker
+	C <-chan Time // The channel on which the ticks are delivered.
+	r runtimeTimer
+}
+
+// NewTicker returns a new Ticker containing a channel that will send the
+// time, in nanoseconds, with a period specified by the duration argument.
+// It adjusts the intervals or drops ticks to make up for slow receivers.
+// The duration d must be greater than zero; if not, NewTicker will panic.
+func NewTicker(d Duration) *Ticker {
+	if d <= 0 {
+		panic(errors.New("non-positive interval for NewTicker"))
+	}
+	// Give the channel a 1-element time buffer.
+	// If the client falls behind while reading, we drop ticks
+	// on the floor until the client catches up.
+	c := make(chan Time, 1)
+	t := &Ticker{
+		C: c,
+		r: runtimeTimer{
+			when:   nano() + int64(d),
+			period: int64(d),
+			f:      sendTime,
+			arg:    c,
+		},
+	}
+	startTimer(&t.r)
+	return t
 }
 
 // Stop turns off a ticker.  After Stop, no more ticks will be sent.
 func (t *Ticker) Stop() {
-	select {
-	case t.shutdown <- true:
-		// ok
-	default:
-		// Stop in progress already
-	}
+	stopTimer(&t.r)
 }
 
 // Tick is a convenience wrapper for NewTicker providing access to the ticking
 // channel only.  Useful for clients that have no need to shut down the ticker.
-func Tick(ns int64) <-chan int64 {
-	if ns <= 0 {
+func Tick(d Duration) <-chan Time {
+	if d <= 0 {
 		return nil
 	}
-	return NewTicker(ns).C
-}
-
-type alarmer struct {
-	wakeUp   chan bool // wakeup signals sent/received here
-	wakeMeAt chan int64
-	wakeTime int64
-}
-
-// Set alarm to go off at time ns, if not already set earlier.
-func (a *alarmer) set(ns int64) {
-	switch {
-	case a.wakeTime > ns:
-		// Next tick we expect is too late; shut down the late runner
-		// and (after fallthrough) start a new wakeLoop.
-		close(a.wakeMeAt)
-		fallthrough
-	case a.wakeMeAt == nil:
-		// There's no wakeLoop, start one.
-		a.wakeMeAt = make(chan int64)
-		a.wakeUp = make(chan bool, 1)
-		go wakeLoop(a.wakeMeAt, a.wakeUp)
-		fallthrough
-	case a.wakeTime == 0:
-		// Nobody else is waiting; it's just us.
-		a.wakeTime = ns
-		a.wakeMeAt <- ns
-	default:
-		// There's already someone scheduled.
-	}
-}
-
-// Channel to notify tickerLoop of new Tickers being created.
-var newTicker chan *Ticker
-
-func startTickerLoop() {
-	newTicker = make(chan *Ticker)
-	go tickerLoop()
-}
-
-// wakeLoop delivers ticks at scheduled times, sleeping until the right moment.
-// If another, earlier Ticker is created while it sleeps, tickerLoop() will start a new
-// wakeLoop and signal that this one is done by closing the wakeMeAt channel.
-func wakeLoop(wakeMeAt chan int64, wakeUp chan bool) {
-	for wakeAt := range wakeMeAt {
-		Sleep(wakeAt - Nanoseconds())
-		wakeUp <- true
-	}
-}
-
-// A single tickerLoop serves all ticks to Tickers.  It waits for two events:
-// either the creation of a new Ticker or a tick from the alarm,
-// signaling a time to wake up one or more Tickers.
-func tickerLoop() {
-	// Represents the next alarm to be delivered.
-	var alarm alarmer
-	var now, wakeTime int64
-	var tickers *Ticker
-	for {
-		select {
-		case t := <-newTicker:
-			// Add Ticker to list
-			t.next = tickers
-			tickers = t
-			// Arrange for a new alarm if this one precedes the existing one.
-			alarm.set(t.nextTick)
-		case <-alarm.wakeUp:
-			now = Nanoseconds()
-			wakeTime = now + 1e15 // very long in the future
-			var prev *Ticker = nil
-			// Scan list of tickers, delivering updates to those
-			// that need it and determining the next wake time.
-			// TODO(r): list should be sorted in time order.
-			for t := tickers; t != nil; t = t.next {
-				select {
-				case <-t.shutdown:
-					// Ticker is done; remove it from list.
-					if prev == nil {
-						tickers = t.next
-					} else {
-						prev.next = t.next
-					}
-					continue
-				default:
-				}
-				if t.nextTick <= now {
-					if len(t.c) == 0 {
-						// Only send if there's room.  We must not block.
-						// The channel is allocated with a one-element
-						// buffer, which is sufficient: if he hasn't picked
-						// up the last tick, no point in sending more.
-						t.c <- now
-					}
-					t.nextTick += t.ns
-					if t.nextTick <= now {
-						// Still behind; advance in one big step.
-						t.nextTick += (now - t.nextTick + t.ns) / t.ns * t.ns
-					}
-				}
-				if t.nextTick < wakeTime {
-					wakeTime = t.nextTick
-				}
-				prev = t
-			}
-			if tickers != nil {
-				// Please send wakeup at earliest required time.
-				// If there are no tickers, don't bother.
-				alarm.wakeTime = wakeTime
-				alarm.wakeMeAt <- wakeTime
-			} else {
-				alarm.wakeTime = 0
-			}
-		}
-	}
-}
-
-var onceStartTickerLoop sync.Once
-
-// NewTicker returns a new Ticker containing a channel that will
-// send the time, in nanoseconds, every ns nanoseconds.  It adjusts the
-// intervals to make up for pauses in delivery of the ticks. The value of
-// ns must be greater than zero; if not, NewTicker will panic.
-func NewTicker(ns int64) *Ticker {
-	if ns <= 0 {
-		panic(errors.New("non-positive interval for NewTicker"))
-	}
-	c := make(chan int64, 1) //  See comment on send in tickerLoop
-	t := &Ticker{
-		C:        c,
-		c:        c,
-		ns:       ns,
-		shutdown: make(chan bool, 1),
-		nextTick: Nanoseconds() + ns,
-	}
-	onceStartTickerLoop.Do(startTickerLoop)
-	// must be run in background so global Tickers can be created
-	go func() { newTicker <- t }()
-	return t
+	return NewTicker(d).C
 }