runtime: convert timers to Go

LGTM=rsc
R=golang-codereviews, ruiu, rsc, daniel.morsing
CC=golang-codereviews, khr
https://golang.org/cl/123700044

src/pkg/runtime/mgc0.c

@@ -2130,3 +2130,13 @@ runtime·getgcmask(byte *p, Type *t, byte **mask, uintptr *len)
 		}
 	}
 }
+
+void runtime·gc_unixnanotime(int64 *now);
+
+int64 runtime·unixnanotime(void)
+{
+	int64 now;
+
+	runtime·gc_unixnanotime(&now);
+	return now;
+}

src/pkg/runtime/netpoll.goc

@@ -39,6 +39,21 @@ enum
 	PollBlockSize	= 4*1024,
 };
 
+// time.go defines the layout of this structure.
+// Keep in sync with time.go.
+typedef struct Timer Timer;
+struct Timer
+{
+	intgo	i;
+	int64	when;
+	int64	period;
+	FuncVal	*fv;
+	Eface	arg;
+};
+
+void	runtime·addtimer(Timer*);
+void	runtime·deltimer(Timer*);
+
 struct PollDesc
 {
 	PollDesc* link;	// in pollcache, protected by pollcache.Lock

src/pkg/runtime/runtime.h

@@ -92,8 +92,6 @@ typedef	struct	Complex64	Complex64;
 typedef	struct	Complex128	Complex128;
 typedef	struct	LibCall		LibCall;
 typedef	struct	WinCallbackContext	WinCallbackContext;
-typedef	struct	Timers		Timers;
-typedef	struct	Timer		Timer;
 typedef	struct	GCStats		GCStats;
 typedef	struct	LFNode		LFNode;
 typedef	struct	ParFor		ParFor;
@@ -519,35 +517,6 @@ enum {
 };
 #endif
 
-struct	Timers
-{
-	Lock	lock;
-	G	*timerproc;
-	bool		sleeping;
-	bool		rescheduling;
-	Note	waitnote;
-	Timer	**t;
-	int32	len;
-	int32	cap;
-};
-
-// Package time knows the layout of this structure.
-// If this struct changes, adjust ../time/sleep.go:/runtimeTimer.
-// For GOOS=nacl, package syscall knows the layout of this structure.
-// If this struct changes, adjust ../syscall/net_nacl.go:/runtimeTimer.
-struct	Timer
-{
-	int32	i;	// heap index
-
-	// Timer wakes up at when, and then at when+period, ... (period > 0 only)
-	// each time calling f(now, arg) in the timer goroutine, so f must be
-	// a well-behaved function and not block.
-	int64	when;
-	int64	period;
-	FuncVal	*fv;
-	Eface	arg;
-};
-
 // Lock-free stack node.
 struct LFNode
 {
@@ -965,8 +934,6 @@ int64	runtime·cputicks(void);
 int64	runtime·tickspersecond(void);
 void	runtime·blockevent(int64, int32);
 extern int64 runtime·blockprofilerate;
-void	runtime·addtimer(Timer*);
-bool	runtime·deltimer(Timer*);
 G*	runtime·netpoll(bool);
 void	runtime·netpollinit(void);
 int32	runtime·netpollopen(uintptr, PollDesc*);

src/pkg/runtime/thunk.s

@@ -11,6 +11,18 @@
 #define JMP B
 #endif
 
+TEXT time·runtimeNano(SB),NOSPLIT,$0-0
+	JMP     runtime·gonanotime(SB)
+
+TEXT time·Sleep(SB),NOSPLIT,$0-0
+	JMP     runtime·timeSleep(SB)
+
+TEXT time·startTimer(SB),NOSPLIT,$0-0
+	JMP     runtime·startTimer(SB)
+
+TEXT time·stopTimer(SB),NOSPLIT,$0-0
+	JMP     runtime·stopTimer(SB)
+
 TEXT sync·runtime_Syncsemacquire(SB),NOSPLIT,$0-0
 	JMP	runtime·syncsemacquire(SB)
 

src/pkg/runtime/time.go

+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Time-related runtime and pieces of package time.
+
+package runtime
+
+import "unsafe"
+
+// Package time knows the layout of this structure.
+// If this struct changes, adjust ../time/sleep.go:/runtimeTimer and netpoll.goc:/timer.
+// For GOOS=nacl, package syscall knows the layout of this structure.
+// If this struct changes, adjust ../syscall/net_nacl.go:/runtimeTimer.
+type timer struct {
+	i int // heap index
+
+	// Timer wakes up at when, and then at when+period, ... (period > 0 only)
+	// each time calling f(now, arg) in the timer goroutine, so f must be
+	// a well-behaved function and not block.
+	when   int64
+	period int64
+	f      func(interface{})
+	arg    interface{}
+}
+
+var timers struct {
+	lock         lock
+	gp           *g
+	created      bool
+	sleeping     bool
+	rescheduling bool
+	waitnote     note
+	t            []*timer
+}
+
+// Package time APIs.
+// Godoc uses the comments in package time, not these.
+
+// time.now is implemented in assembly.
+
+// Sleep puts the current goroutine to sleep for at least ns nanoseconds.
+func timeSleep(ns int64) {
+	if ns <= 0 {
+		return
+	}
+
+	t := new(timer)
+	t.when = gonanotime() + ns
+	t.f = goroutineReady
+	t.arg = getg()
+	golock(&timers.lock)
+	addtimerLocked(t)
+	goparkunlock(&timers.lock, "sleep")
+}
+
+// startTimer adds t to the timer heap.
+func startTimer(t *timer) {
+	if raceenabled {
+		racerelease(unsafe.Pointer(t))
+	}
+	addtimer(t)
+}
+
+// stopTimer removes t from the timer heap if it is there.
+// It returns true if t was removed, false if t wasn't even there.
+func stopTimer(t *timer) bool {
+	return deltimer(t)
+}
+
+// Go runtime.
+
+// Ready the goroutine arg.
+func goroutineReady(arg interface{}) {
+	goready(arg.(*g))
+}
+
+func addtimer(t *timer) {
+	golock(&timers.lock)
+	addtimerLocked(t)
+	gounlock(&timers.lock)
+}
+
+// Add a timer to the heap and start or kick the timer proc.
+// If the new timer is earlier than any of the others.
+// Timers are locked.
+func addtimerLocked(t *timer) {
+	// when must never be negative; otherwise timerproc will overflow
+	// during its delta calculation and never expire other runtime·timers.
+	if t.when < 0 {
+		t.when = 1<<63 - 1
+	}
+	t.i = len(timers.t)
+	timers.t = append(timers.t, t)
+	siftupTimer(t.i)
+	if t.i == 0 {
+		// siftup moved to top: new earliest deadline.
+		if timers.sleeping {
+			timers.sleeping = false
+			gonotewakeup(&timers.waitnote)
+		}
+		if timers.rescheduling {
+			timers.rescheduling = false
+			goready(timers.gp)
+		}
+	}
+	if !timers.created {
+		timers.created = true
+		go timerproc()
+	}
+}
+
+// Delete timer t from the heap.
+// Do not need to update the timerproc: if it wakes up early, no big deal.
+func deltimer(t *timer) bool {
+	// Dereference t so that any panic happens before the lock is held.
+	// Discard result, because t might be moving in the heap.
+	_ = t.i
+
+	golock(&timers.lock)
+	// t may not be registered anymore and may have
+	// a bogus i (typically 0, if generated by Go).
+	// Verify it before proceeding.
+	i := t.i
+	last := len(timers.t) - 1
+	if i < 0 || i > last || timers.t[i] != t {
+		gounlock(&timers.lock)
+		return false
+	}
+	if i != last {
+		timers.t[i] = timers.t[last]
+		timers.t[i].i = i
+	}
+	timers.t[last] = nil
+	timers.t = timers.t[:last]
+	if i != last {
+		siftupTimer(i)
+		siftdownTimer(i)
+	}
+	gounlock(&timers.lock)
+	return true
+}
+
+// Timerproc runs the time-driven events.
+// It sleeps until the next event in the timers heap.
+// If addtimer inserts a new earlier event, addtimer1 wakes timerproc early.
+func timerproc() {
+	timers.gp = getg()
+	timers.gp.issystem = 1
+	for {
+		golock(&timers.lock)
+		timers.sleeping = false
+		now := gonanotime()
+		delta := int64(-1)
+		for {
+			if len(timers.t) == 0 {
+				delta = -1
+				break
+			}
+			t := timers.t[0]
+			delta = t.when - now
+			if delta > 0 {
+				break
+			}
+			if t.period > 0 {
+				// leave in heap but adjust next time to fire
+				t.when += t.period * (1 + -delta/t.period)
+				siftdownTimer(0)
+			} else {
+				// remove from heap
+				last := len(timers.t) - 1
+				if last > 0 {
+					timers.t[0] = timers.t[last]
+					timers.t[0].i = 0
+				}
+				timers.t[last] = nil
+				timers.t = timers.t[:last]
+				if last > 0 {
+					siftdownTimer(0)
+				}
+				t.i = -1 // mark as removed
+			}
+			f := t.f
+			arg := t.arg
+			gounlock(&timers.lock)
+			if raceenabled {
+				raceacquire(unsafe.Pointer(t))
+			}
+			f(arg)
+			golock(&timers.lock)
+		}
+		if delta < 0 {
+			// No timers left - put goroutine to sleep.
+			timers.rescheduling = true
+			timers.gp.isbackground = 1
+			goparkunlock(&timers.lock, "timer goroutine (idle)")
+			timers.gp.isbackground = 0
+			continue
+		}
+		// At least one timer pending.  Sleep until then.
+		timers.sleeping = true
+		gonoteclear(&timers.waitnote)
+		gounlock(&timers.lock)
+		gonotetsleepg(&timers.waitnote, delta)
+	}
+}
+
+// Heap maintenance algorithms.
+
+func siftupTimer(i int) {
+	t := timers.t
+	when := t[i].when
+	tmp := t[i]
+	for i > 0 {
+		p := (i - 1) / 4 // parent
+		if when >= t[p].when {
+			break
+		}
+		t[i] = t[p]
+		t[i].i = i
+		t[p] = tmp
+		t[p].i = p
+		i = p
+	}
+}
+
+func siftdownTimer(i int) {
+	t := timers.t
+	n := len(t)
+	when := t[i].when
+	tmp := t[i]
+	for {
+		c := i*4 + 1 // left child
+		c3 := c + 2  // mid child
+		if c >= n {
+			break
+		}
+		w := t[c].when
+		if c+1 < n && t[c+1].when < w {
+			w = t[c+1].when
+			c++
+		}
+		if c3 < n {
+			w3 := t[c3].when
+			if c3+1 < n && t[c3+1].when < w3 {
+				w3 = t[c3+1].when
+				c3++
+			}
+			if w3 < w {
+				w = w3
+				c = c3
+			}
+		}
+		if w >= when {
+			break
+		}
+		t[i] = t[c]
+		t[i].i = i
+		t[c] = tmp
+		t[c].i = c
+		i = c
+	}
+}

src/pkg/runtime/time.goc

-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Time-related runtime and pieces of package time.
-
-package time
-
-#include "runtime.h"
-#include "defs_GOOS_GOARCH.h"
-#include "os_GOOS.h"
-#include "arch_GOARCH.h"
-#include "malloc.h"
-#include "race.h"
-
-enum {
-	debug = 0,
-};
-
-static Timers timers;
-static void addtimer(Timer*);
-static void dumptimers(int8*);
-
-// nacl fake time support. 
-int64 runtime·timens;
-
-// Package time APIs.
-// Godoc uses the comments in package time, not these.
-
-// time.now is implemented in assembly.
-
-// runtimeNano returns the current value of the runtime clock in nanoseconds.
-func runtimeNano() (ns int64) {
-	ns = runtime·nanotime();
-}
-
-// Sleep puts the current goroutine to sleep for at least ns nanoseconds.
-func Sleep(ns int64) {
-	runtime·tsleep(ns, runtime·gostringnocopy((byte*)"sleep"));
-}
-
-// startTimer adds t to the timer heap.
-func startTimer(t *Timer) {
-	if(raceenabled)
-		runtime·racerelease(t);
-	runtime·addtimer(t);
-}
-
-// stopTimer removes t from the timer heap if it is there.
-// It returns true if t was removed, false if t wasn't even there.
-func stopTimer(t *Timer) (stopped bool) {
-	stopped = runtime·deltimer(t);
-}
-
-// C runtime.
-
-void runtime·gc_unixnanotime(int64 *now);
-
-int64 runtime·unixnanotime(void)
-{
-	int64 now;
-
-	runtime·gc_unixnanotime(&now);
-	return now;
-}
-
-static void timerproc(void);
-static void siftup(int32);
-static void siftdown(int32);
-
-// Ready the goroutine e.data.
-static void
-ready(Eface e)
-{
-	runtime·ready(e.data);
-}
-
-static FuncVal readyv = {(void(*)(void))ready};
-
-// Put the current goroutine to sleep for ns nanoseconds.
-void
-runtime·tsleep(int64 ns, String reason)
-{
-	Timer t;
-
-	if(ns <= 0)
-		return;
-
-	t.when = runtime·nanotime() + ns;
-	t.period = 0;
-	t.fv = &readyv;
-	t.arg.data = g;
-	runtime·lock(&timers.lock);
-	addtimer(&t);
-	runtime·parkunlock(&timers.lock, reason);
-}
-
-static FuncVal timerprocv = {timerproc};
-
-void
-runtime·addtimer(Timer *t)
-{
-	runtime·lock(&timers.lock);
-	addtimer(t);
-	runtime·unlock(&timers.lock);
-}
-
-// Add a timer to the heap and start or kick the timer proc
-// if the new timer is earlier than any of the others.
-static void
-addtimer(Timer *t)
-{
-	int32 n;
-	Timer **nt;
-
-	// when must never be negative; otherwise timerproc will overflow
-	// during its delta calculation and never expire other timers.
-	if(t->when < 0)
-		t->when = (1LL<<63)-1;
-
-	if(timers.len >= timers.cap) {
-		// Grow slice.
-		n = 16;
-		if(n <= timers.cap)
-			n = timers.cap*3 / 2;
-		nt = runtime·mallocgc(n*sizeof nt[0], nil, 0);
-		runtime·memmove(nt, timers.t, timers.len*sizeof nt[0]);
-		timers.t = nt;
-		timers.cap = n;
-	}
-	t->i = timers.len++;
-	timers.t[t->i] = t;
-	siftup(t->i);
-	if(t->i == 0) {
-		// siftup moved to top: new earliest deadline.
-		if(timers.sleeping) {
-			timers.sleeping = false;
-			runtime·notewakeup(&timers.waitnote);
-		}
-		if(timers.rescheduling) {
-			timers.rescheduling = false;
-			runtime·ready(timers.timerproc);
-		}
-	}
-	if(timers.timerproc == nil) {
-		timers.timerproc = runtime·newproc1(&timerprocv, nil, 0, 0, addtimer);
-		timers.timerproc->issystem = true;
-	}
-	if(debug)
-		dumptimers("addtimer");
-}
-
-// Delete timer t from the heap.
-// Do not need to update the timerproc:
-// if it wakes up early, no big deal.
-bool
-runtime·deltimer(Timer *t)
-{
-	int32 i;
-
-	// Dereference t so that any panic happens before the lock is held.
-	// Discard result, because t might be moving in the heap.
-	i = t->i;
-	USED(i);
-
-	runtime·lock(&timers.lock);
-
-	// t may not be registered anymore and may have
-	// a bogus i (typically 0, if generated by Go).
-	// Verify it before proceeding.
-	i = t->i;
-	if(i < 0 || i >= timers.len || timers.t[i] != t) {
-		runtime·unlock(&timers.lock);
-		return false;
-	}
-
-	timers.len--;
-	if(i == timers.len) {
-		timers.t[i] = nil;
-	} else {
-		timers.t[i] = timers.t[timers.len];
-		timers.t[timers.len] = nil;
-		timers.t[i]->i = i;
-		siftup(i);
-		siftdown(i);
-	}
-	if(debug)
-		dumptimers("deltimer");
-	runtime·unlock(&timers.lock);
-	return true;
-}
-
-// Timerproc runs the time-driven events.
-// It sleeps until the next event in the timers heap.
-// If addtimer inserts a new earlier event, addtimer
-// wakes timerproc early.
-static void
-timerproc(void)
-{
-	int64 delta, now;
-	Timer *t;
-	void (*f)(Eface);
-	Eface arg;
-
-	for(;;) {
-		runtime·lock(&timers.lock);
-		timers.sleeping = false;
-		now = runtime·nanotime();
-		for(;;) {
-			if(timers.len == 0) {
-				delta = -1;
-				break;
-			}
-			t = timers.t[0];
-			delta = t->when - now;
-			if(delta > 0)
-				break;
-			if(t->period > 0) {
-				// leave in heap but adjust next time to fire
-				t->when += t->period * (1 + -delta/t->period);
-				siftdown(0);
-			} else {
-				// remove from heap
-				timers.t[0] = timers.t[--timers.len];
-				timers.t[0]->i = 0;
-				siftdown(0);
-				t->i = -1;  // mark as removed
-			}
-			f = (void*)t->fv->fn;
-			arg = t->arg;
-			runtime·unlock(&timers.lock);
-			if(raceenabled)
-				runtime·raceacquire(t);
-			f(arg);
-
-			// clear f and arg to avoid leak while sleeping for next timer
-			f = nil;
-			USED(f);
-			arg.type = nil;
-			arg.data = nil;
-			USED(&arg);
-
-			runtime·lock(&timers.lock);
-		}
-		if(delta < 0) {
-			// No timers left - put goroutine to sleep.
-			timers.rescheduling = true;
-			g->isbackground = true;
-			runtime·parkunlock(&timers.lock, runtime·gostringnocopy((byte*)"timer goroutine (idle)"));
-			g->isbackground = false;
-			continue;
-		}
-		// At least one timer pending.  Sleep until then.
-		timers.sleeping = true;
-		runtime·noteclear(&timers.waitnote);
-		runtime·unlock(&timers.lock);
-		runtime·notetsleepg(&timers.waitnote, delta);
-	}
-}
-
-// heap maintenance algorithms.
-
-static void
-siftup(int32 i)
-{
-	int32 p;
-	int64 when;
-	Timer **t, *tmp;
-
-	t = timers.t;
-	when = t[i]->when;
-	tmp = t[i];
-	while(i > 0) {
-		p = (i-1)/4;  // parent
-		if(when >= t[p]->when)
-			break;
-		t[i] = t[p];
-		t[i]->i = i;
-		t[p] = tmp;
-		tmp->i = p;
-		i = p;
-	}
-}
-
-static void
-siftdown(int32 i)
-{
-	int32 c, c3, len;
-	int64 when, w, w3;
-	Timer **t, *tmp;
-
-	t = timers.t;
-	len = timers.len;
-	when = t[i]->when;
-	tmp = t[i];
-	for(;;) {
-		c = i*4 + 1;  // left child
-		c3 = c + 2;  // mid child
-		if(c >= len) {
-			break;
-		}
-		w = t[c]->when;
-		if(c+1 < len && t[c+1]->when < w) {
-			w = t[c+1]->when;
-			c++;
-		}
-		if(c3 < len) {
-			w3 = t[c3]->when;
-			if(c3+1 < len && t[c3+1]->when < w3) {
-				w3 = t[c3+1]->when;
-				c3++;
-			}
-			if(w3 < w) {
-				w = w3;
-				c = c3;
-			}
-		}
-		if(w >= when)
-			break;
-		t[i] = t[c];
-		t[i]->i = i;
-		t[c] = tmp;
-		tmp->i = c;
-		i = c;
-	}
-}
-
-static void
-dumptimers(int8 *msg)
-{
-	Timer *t;
-	int32 i;
-
-	runtime·printf("timers: %s\n", msg);
-	for(i = 0; i < timers.len; i++) {
-		t = timers.t[i];
-		runtime·printf("\t%d\t%p:\ti %d when %D period %D fn %p\n",
-				i, t, t->i, t->when, t->period, t->fv->fn);
-	}
-	runtime·printf("\n");
-}

src/pkg/syscall/net_nacl.go

@@ -18,7 +18,7 @@ import (
 // Really for use by package time, but we cannot import time here.
 
 type runtimeTimer struct {
-	i      int32
+	i      int
 	when   int64
 	period int64
 	f      func(interface{}) // NOTE: must not be closure

src/pkg/time/sleep.go

@@ -14,7 +14,7 @@ func runtimeNano() int64
 // Interface to timers implemented in package runtime.
 // Must be in sync with ../runtime/runtime.h:/^struct.Timer$
 type runtimeTimer struct {
-	i      int32
+	i      int
 	when   int64
 	period int64
 	f      func(interface{}) // NOTE: must not be closure