sync: implement simple pooling in sync.Pool

src/sync/pool.go

@@ -1,13 +1,18 @@
 package sync
 
-// Pool is a very simple implementation of sync.Pool. It does not actually
-// implement a pool.
+// Pool is a very simple implementation of sync.Pool.
 type Pool struct {
-	New func() interface{}
+	New   func() interface{}
+	items []interface{}
 }
 
 // Get returns the value of calling Pool.New().
 func (p *Pool) Get() interface{} {
+	if len(p.items) > 0 {
+		x := p.items[len(p.items)-1]
+		p.items = p.items[:len(p.items)-1]
+		return x
+	}
 	if p.New == nil {
 		return nil
 	}
@@ -16,4 +21,5 @@ func (p *Pool) Get() interface{} {
 
 // Put drops the value put into the pool.
 func (p *Pool) Put(x interface{}) {
+	p.items = append(p.items, x)
 }