mirror of
https://github.com/golang/go
synced 2024-11-06 02:36:15 -07:00
73 lines
1.2 KiB
Go
73 lines
1.2 KiB
Go
|
// run
|
||
|
|
|
||
|
|
// Copyright 2018 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.
|
||
|
|
|
||
|
|
package main
|
||
|
|
|
||
|
|
import "runtime"
|
||
|
|
|
||
|
|
var finalized bool
|
||
|
|
var err string
|
||
|
|
|
||
|
|
type HeapObj [8]int64
|
||
|
|
|
||
|
|
const filler int64 = 0x123456789abcdef0
|
||
|
|
|
||
|
|
func (h *HeapObj) init() {
|
||
|
|
for i := 0; i < len(*h); i++ {
|
||
|
|
h[i] = filler
|
||
|
|
}
|
||
|
|
}
|
||
|
|
func (h *HeapObj) check() {
|
||
|
|
for i := 0; i < len(*h); i++ {
|
||
|
|
if h[i] != filler {
|
||
|
|
err = "filler overwritten"
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
type StackObj struct {
|
||
|
|
h *HeapObj
|
||
|
|
}
|
||
|
|
|
||
|
|
func gc(shouldFinalize bool) {
|
||
|
|
runtime.GC()
|
||
|
|
runtime.GC()
|
||
|
|
runtime.GC()
|
||
|
|
if shouldFinalize != finalized {
|
||
|
|
err = "heap object finalized at the wrong time"
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
var s StackObj
|
||
|
|
s.h = new(HeapObj)
|
||
|
|
s.h.init()
|
||
|
|
runtime.SetFinalizer(s.h, func(h *HeapObj) {
|
||
|
|
finalized = true
|
||
|
|
})
|
||
|
|
gc(false)
|
||
|
|
h := g(&s)
|
||
|
|
gc(false)
|
||
|
|
h.check()
|
||
|
|
gc(true) // finalize here, after return value's last use. (Go1.11 never runs the finalizer.)
|
||
|
|
if err != "" {
|
||
|
|
panic(err)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func g(p *StackObj) (v *HeapObj) {
|
||
|
|
gc(false)
|
||
|
|
v = p.h // last use of the stack object. the only reference to the heap object is in the return slot.
|
||
|
|
gc(false)
|
||
|
|
defer func() {
|
||
|
|
gc(false)
|
||
|
|
recover()
|
||
|
|
gc(false)
|
||
|
|
}()
|
||
|
|
*(*int)(nil) = 0
|
||
|
|
return
|
||
|
|
}
|