runtime: allow SetFinalizer with a func(interface{})

Fixes #5368.

R=golang-dev, dvyukov
CC=golang-dev, rsc
https://golang.org/cl/11858043

src/pkg/runtime/extern.go

@@ -122,8 +122,9 @@ func funcentry_go(*Func) uintptr
 // The argument x must be a pointer to an object allocated by
 // calling new or by taking the address of a composite literal.
 // The argument f must be a function that takes a single argument
-// of x's type and can have arbitrary ignored return values.
-// If either of these is not true, SetFinalizer aborts the program.
+// of x's type or interface{}, and can have arbitrary ignored return
+// values. If either of these is not true, SetFinalizer aborts the
+// program.
 //
 // Finalizers are run in dependency order: if A points at B, both have
 // finalizers, and they are otherwise unreachable, only the finalizer

src/pkg/runtime/malloc.goc

@@ -799,6 +799,8 @@ func SetFinalizer(obj Eface, finalizer Eface) {
 	int32 i;
 	uintptr nret;
 	Type *t;
+	Type *fint;
+	PtrType *ot;
 
 	if(obj.type == nil) {
 		runtime·printf("runtime.SetFinalizer: first argument is nil interface\n");
@@ -813,11 +815,17 @@ func SetFinalizer(obj Eface, finalizer Eface) {
 		goto throw;
 	}
 	nret = 0;
+	ot = nil;
 	if(finalizer.type != nil) {
 		if(finalizer.type->kind != KindFunc)
 			goto badfunc;
 		ft = (FuncType*)finalizer.type;
-		if(ft->dotdotdot || ft->in.len != 1 || *(Type**)ft->in.array != obj.type)
+		if(ft->dotdotdot || ft->in.len != 1)
+			goto badfunc;
+		fint = *(Type**)ft->in.array;
+		if(fint->kind == KindInterface && ((InterfaceType*)fint)->mhdr.len == 0)
+			ot = (PtrType*)obj.type;
+		else if(fint != obj.type)
 			goto badfunc;
 
 		// compute size needed for return parameters
@@ -828,14 +836,14 @@ func SetFinalizer(obj Eface, finalizer Eface) {
 		nret = ROUND(nret, sizeof(void*));
 	}
 	
-	if(!runtime·addfinalizer(obj.data, finalizer.data, nret)) {
+	if(!runtime·addfinalizer(obj.data, finalizer.data, nret, ot)) {
 		runtime·printf("runtime.SetFinalizer: finalizer already set\n");
 		goto throw;
 	}
 	return;
 
 badfunc:
-	runtime·printf("runtime.SetFinalizer: second argument is %S, not func(%S)\n", *finalizer.type->string, *obj.type->string);
+	runtime·printf("runtime.SetFinalizer: second argument is %S, not func(%S) or func(interface{})\n", *finalizer.type->string, *obj.type->string);
 throw:
 	runtime·throw("runtime.SetFinalizer");
 }

src/pkg/runtime/malloc.h

@@ -480,7 +480,7 @@ int32	runtime·gcprocs(void);
 void	runtime·helpgc(int32 nproc);
 void	runtime·gchelper(void);
 
-bool	runtime·getfinalizer(void *p, bool del, FuncVal **fn, uintptr *nret);
+bool	runtime·getfinalizer(void *p, bool del, FuncVal **fn, uintptr *nret, void **ot);
 void	runtime·walkfintab(void (*fn)(void*));
 
 enum

src/pkg/runtime/mfinal.c

@@ -13,6 +13,7 @@ struct Fin
 {
 	FuncVal *fn;
 	uintptr nret;
+	void *ot;
 };
 
 // Finalizer hash table.  Direct hash, linear scan, at most 3/4 full.
@@ -42,7 +43,7 @@ static struct {
 } fintab[TABSZ];
 
 static void
-addfintab(Fintab *t, void *k, FuncVal *fn, uintptr nret)
+addfintab(Fintab *t, void *k, FuncVal *fn, uintptr nret, void *ot)
 {
 	int32 i, j;
 
@@ -67,6 +68,7 @@ ret:
 	t->key[i] = k;
 	t->val[i].fn = fn;
 	t->val[i].nret = nret;
+	t->val[i].ot = ot;
 }
 
 static bool
@@ -87,6 +89,7 @@ lookfintab(Fintab *t, void *k, bool del, Fin *f)
 				t->key[i] = (void*)-1;
 				t->val[i].fn = nil;
 				t->val[i].nret = 0;
+				t->val[i].ot = nil;
 				t->ndead++;
 			}
 			return true;
@@ -123,7 +126,7 @@ resizefintab(Fintab *tab)
 	for(i=0; i<tab->max; i++) {
 		k = tab->key[i];
 		if(k != nil && k != (void*)-1)
-			addfintab(&newtab, k, tab->val[i].fn, tab->val[i].nret);
+			addfintab(&newtab, k, tab->val[i].fn, tab->val[i].nret, tab->val[i].ot);
 	}
 	
 	runtime·free(tab->key);
@@ -137,7 +140,7 @@ resizefintab(Fintab *tab)
 }
 
 bool
-runtime·addfinalizer(void *p, FuncVal *f, uintptr nret)
+runtime·addfinalizer(void *p, FuncVal *f, uintptr nret, void *ot)
 {
 	Fintab *tab;
 	byte *base;
@@ -166,7 +169,7 @@ runtime·addfinalizer(void *p, FuncVal *f, uintptr nret)
 		resizefintab(tab);
 	}
 
-	addfintab(tab, p, f, nret);
+	addfintab(tab, p, f, nret, ot);
 	runtime·setblockspecial(p, true);
 	runtime·unlock(tab);
 	return true;
@@ -175,7 +178,7 @@ runtime·addfinalizer(void *p, FuncVal *f, uintptr nret)
 // get finalizer; if del, delete finalizer.
 // caller is responsible for updating RefHasFinalizer (special) bit.
 bool
-runtime·getfinalizer(void *p, bool del, FuncVal **fn, uintptr *nret)
+runtime·getfinalizer(void *p, bool del, FuncVal **fn, uintptr *nret, void **ot)
 {
 	Fintab *tab;
 	bool res;
@@ -189,6 +192,7 @@ runtime·getfinalizer(void *p, bool del, FuncVal **fn, uintptr *nret)
 		return false;
 	*fn = f.fn;
 	*nret = f.nret;
+	*ot = f.ot;
 	return true;
 }
 

src/pkg/runtime/mfinal_test.go

@@ -9,8 +9,94 @@ import (
 	"sync"
 	"sync/atomic"
 	"testing"
+	"time"
 )
 
+func TestFinalizerTypeSucceed(t *testing.T) {
+	if runtime.GOARCH != "amd64" {
+		t.Skipf("Skipping on non-amd64 machine")
+	}
+	ch := make(chan bool)
+	func() {
+		v := new(int)
+		*v = 97531
+		runtime.SetFinalizer(v, func(v *int) {
+			if *v != 97531 {
+				t.Errorf("*int in finalizer has the wrong value: %d\n", *v)
+			}
+			close(ch)
+		})
+		v = nil
+	}()
+	runtime.GC()
+	select {
+	case <-ch:
+	case <-time.After(time.Second * 4):
+		t.Errorf("Finalizer set by SetFinalizer(*int, func(*int)) didn't run")
+	}
+}
+
+func TestFinalizerInterface(t *testing.T) {
+	if runtime.GOARCH != "amd64" {
+		t.Skipf("Skipping on non-amd64 machine")
+	}
+	ch := make(chan bool)
+	func() {
+		v := new(int)
+		*v = 97531
+		runtime.SetFinalizer(v, func(v interface{}) {
+			i, ok := v.(*int)
+			if !ok {
+				t.Errorf("Expected *int from interface{} in finalizer, got %v", *i)
+			}
+			if *i != 97531 {
+				t.Errorf("*int from interface{} has the wrong value: %d\n", *i)
+			}
+			close(ch)
+		})
+		v = nil
+	}()
+	runtime.GC()
+	select {
+	case <-ch:
+	case <-time.After(time.Second * 4):
+		t.Errorf("Finalizer set by SetFinalizer(*int, func(interface{})) didn't run")
+	}
+}
+
+type bigValue struct {
+	fill uint64
+	it   bool
+	up   string
+}
+
+func TestFinalizerInterfaceBig(t *testing.T) {
+	if runtime.GOARCH != "amd64" {
+		t.Skipf("Skipping on non-amd64 machine")
+	}
+	ch := make(chan bool)
+	func() {
+		v := &bigValue{0xDEADBEEFDEADBEEF, true, "It matters not how strait the gate"}
+		runtime.SetFinalizer(v, func(v interface{}) {
+			i, ok := v.(*bigValue)
+			if !ok {
+				t.Errorf("Expected *bigValue from interface{} in finalizer, got %v", *i)
+			}
+			if i.fill != 0xDEADBEEFDEADBEEF && i.it != true && i.up != "It matters not how strait the gate" {
+				t.Errorf("*bigValue from interface{} has the wrong value: %d\n", *i)
+			}
+			close(ch)
+		})
+		v = nil
+	}()
+	runtime.GC()
+	select {
+	case <-ch:
+	case <-time.After(time.Second * 4):
+		t.Errorf("Finalizer set by SetFinalizer(*bigValue, func(interface{})) didn't run")
+	}
+}
+
 func fin(v *int) {
 }
 

src/pkg/runtime/mgc0.c

@@ -109,6 +109,7 @@ struct Finalizer
 	FuncVal *fn;
 	void *arg;
 	uintptr nret;
+	PtrType *ot;
 };
 
 typedef struct FinBlock FinBlock;
@@ -1583,10 +1584,11 @@ handlespecial(byte *p, uintptr size)
 {
 	FuncVal *fn;
 	uintptr nret;
+	PtrType *ot;
 	FinBlock *block;
 	Finalizer *f;
 
-	if(!runtime·getfinalizer(p, true, &fn, &nret)) {
+	if(!runtime·getfinalizer(p, true, &fn, &nret, &ot)) {
 		runtime·setblockspecial(p, false);
 		runtime·MProf_Free(p, size);
 		return false;
@@ -1609,6 +1611,7 @@ handlespecial(byte *p, uintptr size)
 	finq->cnt++;
 	f->fn = fn;
 	f->nret = nret;
+	f->ot = ot;
 	f->arg = p;
 	runtime·unlock(&finlock);
 	return true;
@@ -2272,6 +2275,7 @@ runfinq(void)
 	FinBlock *fb, *next;
 	byte *frame;
 	uint32 framesz, framecap, i;
+	Eface *ef;
 
 	frame = nil;
 	framecap = 0;
@@ -2291,7 +2295,7 @@ runfinq(void)
 			next = fb->next;
 			for(i=0; i<fb->cnt; i++) {
 				f = &fb->fin[i];
-				framesz = sizeof(uintptr) + f->nret;
+				framesz = sizeof(Eface) + f->nret;
 				if(framecap < framesz) {
 					runtime·free(frame);
 					// The frame does not contain pointers interesting for GC,
@@ -2301,10 +2305,17 @@ runfinq(void)
 					frame = runtime·mallocgc(framesz, 0, FlagNoPointers|FlagNoInvokeGC);
 					framecap = framesz;
 				}
+				if(f->ot == nil)
 					*(void**)frame = f->arg;
-				reflect·call(f->fn, frame, sizeof(uintptr) + f->nret);
+				else {
+					ef = (Eface*)frame;
+					ef->type = f->ot;
+					ef->data = f->arg;
+				}
+				reflect·call(f->fn, frame, framesz);
 				f->fn = nil;
 				f->arg = nil;
+				f->ot = nil;
 			}
 			fb->cnt = 0;
 			fb->next = finc;

src/pkg/runtime/runtime.h

@@ -808,7 +808,7 @@ uintptr	runtime·ifacehash(Iface, uintptr);
 uintptr	runtime·efacehash(Eface, uintptr);
 void*	runtime·malloc(uintptr size);
 void	runtime·free(void *v);
-bool	runtime·addfinalizer(void*, FuncVal *fn, uintptr);
+bool	runtime·addfinalizer(void*, FuncVal *fn, uintptr, void*);
 void	runtime·runpanic(Panic*);
 uintptr	runtime·getcallersp(void*);
 int32	runtime·mcount(void);