82 lines
1.9 KiB
Go
82 lines
1.9 KiB
Go
package main
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import (
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"fmt"
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"sync/atomic"
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)
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const (
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White, Grey, Black = 0, 1, 2
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)
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type SimObject struct {
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ID string
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Color int32
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Ref *SimObject
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}
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func (o *SimObject) SetColor(c int32) { atomic.StoreInt32(&o.Color, c) }
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func (o *SimObject) GetColor() int32 { return atomic.LoadInt32(&o.Color) }
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// 插入屏障：黑色→白色时标灰新对象（概念模拟）
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func InsertionBarrier(parent, child *SimObject) bool {
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if parent.GetColor() == Black && child.GetColor() == White {
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child.SetColor(Grey)
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return true
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}
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return false
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}
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// 删除屏障：无条件标灰旧引用（概念模拟）
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func DeletionBarrier(oldRef *SimObject) bool {
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if oldRef != nil && oldRef.GetColor() != Black {
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oldRef.SetColor(Grey)
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return true
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}
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return false
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}
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func colorName(c int32) string {
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switch c {
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case White:
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return "白"
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case Grey:
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return "灰"
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case Black:
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return "黑"
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}
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return "未知"
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}
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func main() {
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fmt.Println("=== 场景1：无屏障 → 漏标风险 ===")
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A := &SimObject{ID: "A", Color: Black}
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B := &SimObject{ID: "B", Color: White}
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A.Ref = B
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C := &SimObject{ID: "C", Color: White}
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A.Ref = C
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fmt.Printf("⚠️ B 状态: %s (孤立白色对象，应被回收)\n", colorName(B.GetColor()))
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fmt.Println("\n=== 场景2：插入屏障保护 ===")
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A.SetColor(Black)
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B.SetColor(White)
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A.Ref = B
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D := &SimObject{ID: "D", Color: White}
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if InsertionBarrier(A, D) {
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fmt.Printf("🛡️ [插入] A(黑)→D(白) → D 标灰\n")
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}
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A.Ref = D
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fmt.Printf("✅ D 状态: %s (被屏障保护)\n", colorName(D.GetColor()))
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fmt.Println("\n=== 场景3：删除屏障保护 ===")
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E := &SimObject{ID: "E", Color: Black}
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F := &SimObject{ID: "F", Color: White}
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E.Ref = F
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G := &SimObject{ID: "G", Color: White}
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if DeletionBarrier(E.Ref) {
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fmt.Printf("🛡️ [删除] 旧引用 F(白) → F 标灰\n")
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}
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E.Ref = G
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fmt.Printf("✅ F 状态: %s (被屏障重新标灰)\n", colorName(F.GetColor()))
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}
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