1 files changed, 137 insertions, 0 deletions
diff --git a/src/runtime/lfstack_test.go b/src/runtime/lfstack_test.go
new file mode 100644
index 0000000..e36297e
--- /dev/null
+++ b/src/runtime/lfstack_test.go
@@ -0,0 +1,137 @@
+// Copyright 2012 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 runtime_test
+
+import (
+	"math/rand"
+	. "runtime"
+	"testing"
+	"unsafe"
+)
+
+type MyNode struct {
+	LFNode
+	data int
+}
+
+// allocMyNode allocates nodes that are stored in an lfstack
+// outside the Go heap.
+// We require lfstack objects to live outside the heap so that
+// checkptr passes on the unsafe shenanigans used.
+func allocMyNode(data int) *MyNode {
+	n := (*MyNode)(PersistentAlloc(unsafe.Sizeof(MyNode{})))
+	LFNodeValidate(&n.LFNode)
+	n.data = data
+	return n
+}
+
+func fromMyNode(node *MyNode) *LFNode {
+	return (*LFNode)(unsafe.Pointer(node))
+}
+
+func toMyNode(node *LFNode) *MyNode {
+	return (*MyNode)(unsafe.Pointer(node))
+}
+
+var global any
+
+func TestLFStack(t *testing.T) {
+	stack := new(uint64)
+	global = stack // force heap allocation
+
+	// Check the stack is initially empty.
+	if LFStackPop(stack) != nil {
+		t.Fatalf("stack is not empty")
+	}
+
+	// Push one element.
+	node := allocMyNode(42)
+	LFStackPush(stack, fromMyNode(node))
+
+	// Push another.
+	node = allocMyNode(43)
+	LFStackPush(stack, fromMyNode(node))
+
+	// Pop one element.
+	node = toMyNode(LFStackPop(stack))
+	if node == nil {
+		t.Fatalf("stack is empty")
+	}
+	if node.data != 43 {
+		t.Fatalf("no lifo")
+	}
+
+	// Pop another.
+	node = toMyNode(LFStackPop(stack))
+	if node == nil {
+		t.Fatalf("stack is empty")
+	}
+	if node.data != 42 {
+		t.Fatalf("no lifo")
+	}
+
+	// Check the stack is empty again.
+	if LFStackPop(stack) != nil {
+		t.Fatalf("stack is not empty")
+	}
+	if *stack != 0 {
+		t.Fatalf("stack is not empty")
+	}
+}
+
+func TestLFStackStress(t *testing.T) {
+	const K = 100
+	P := 4 * GOMAXPROCS(-1)
+	N := 100000
+	if testing.Short() {
+		N /= 10
+	}
+	// Create 2 stacks.
+	stacks := [2]*uint64{new(uint64), new(uint64)}
+	// Push K elements randomly onto the stacks.
+	sum := 0
+	for i := 0; i < K; i++ {
+		sum += i
+		node := allocMyNode(i)
+		LFStackPush(stacks[i%2], fromMyNode(node))
+	}
+	c := make(chan bool, P)
+	for p := 0; p < P; p++ {
+		go func() {
+			r := rand.New(rand.NewSource(rand.Int63()))
+			// Pop a node from a random stack, then push it onto a random stack.
+			for i := 0; i < N; i++ {
+				node := toMyNode(LFStackPop(stacks[r.Intn(2)]))
+				if node != nil {
+					LFStackPush(stacks[r.Intn(2)], fromMyNode(node))
+				}
+			}
+			c <- true
+		}()
+	}
+	for i := 0; i < P; i++ {
+		<-c
+	}
+	// Pop all elements from both stacks, and verify that nothing lost.
+	sum2 := 0
+	cnt := 0
+	for i := 0; i < 2; i++ {
+		for {
+			node := toMyNode(LFStackPop(stacks[i]))
+			if node == nil {
+				break
+			}
+			cnt++
+			sum2 += node.data
+			node.Next = 0
+		}
+	}
+	if cnt != K {
+		t.Fatalf("Wrong number of nodes %d/%d", cnt, K)
+	}
+	if sum2 != sum {
+		t.Fatalf("Wrong sum %d/%d", sum2, sum)
+	}
+}