From 0e840e1d4fb21bf7d080abc5c8570d3c3a80a1a8 Mon Sep 17 00:00:00 2001
From: Hans Moog <hm@mkjc.net>
Date: Wed, 24 Jul 2019 11:41:29 +0200
Subject: [PATCH] Feat: started experimenting with a weakmap implementation
(tests)
---
packages/datastructure/weakmap_test.go | 92 ++++++++++++++++++++++++++
1 file changed, 92 insertions(+)
create mode 100644 packages/datastructure/weakmap_test.go
diff --git a/packages/datastructure/weakmap_test.go b/packages/datastructure/weakmap_test.go
new file mode 100644
index 00000000..2c239962
--- /dev/null
+++ b/packages/datastructure/weakmap_test.go
@@ -0,0 +1,92 @@
+package datastructure
+
+import (
+ "fmt"
+ "testing"
+)
+import "runtime"
+import "unsafe"
+import "errors"
+import "time"
+
+func TestWeakmap(t *testing.T) {
+ generateA(6)
+ fmt.Println("")
+
+ debugWeakMap(6)
+ fmt.Println("")
+
+ runtime.GC()
+ fmt.Println("GC runned.")
+
+ time.Sleep(1 * time.Second)
+
+ debugWeakMap(6)
+}
+
+func generateA(n int) {
+
+ for i := 0; i < n; i++ {
+ a := NewA()
+ WMap.Add(a)
+ fmt.Println("Added to WM A with id =", a.Id)
+ }
+
+}
+
+func debugWeakMap(n int) {
+ for i := 0; i < n; i++ {
+ if WMap.Has(i) {
+ fmt.Println("Has id =", i)
+ } else {
+ fmt.Println("Hasn't id =", i)
+ }
+ }
+}
+
+var aId int
+
+func NewA() *A {
+ aId++
+ return &A{aId}
+}
+
+var WMap = &WeakMap{weakMap: make(map[int]uintptr)}
+
+type WeakMap struct {
+ weakMap map[int]uintptr
+}
+
+type A struct {
+ Id int
+}
+
+func (w *WeakMap) Add(a *A) {
+ runtime.SetFinalizer(a, finalizer)
+
+ w.weakMap[a.Id] = uintptr(unsafe.Pointer(a))
+}
+
+func (w *WeakMap) Get(id int) (*A, error) {
+ if !w.Has(id) {
+ return nil, errors.New("")
+ }
+
+ a := (*A)(unsafe.Pointer(w.weakMap[id]))
+
+ return a, nil
+}
+
+func (w *WeakMap) Has(id int) bool {
+ _, ok := w.weakMap[id]
+ return ok
+}
+
+func (w *WeakMap) Remove(a *A) {
+ delete(w.weakMap, a.Id)
+}
+
+func finalizer(a *A) {
+ fmt.Println(a.Id)
+ WMap.Remove(a)
+}
--
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