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// 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
}
func fromMyNode(node *MyNode) *LFNode {
return (*LFNode)(unsafe.Pointer(node))
}
func toMyNode(node *LFNode) *MyNode {
return (*MyNode)(unsafe.Pointer(node))
}
func TestLFStack(t *testing.T) {
stack := new(uint64)
// Need to keep additional referenfces to nodes, the stack is not all that type-safe.
var nodes []*MyNode
// Check the stack is initially empty.
if LFStackPop(stack) != nil {
t.Fatalf("stack is not empty")
}
// Push one element.
node := &MyNode{data: 42}
nodes = append(nodes, node)
LFStackPush(stack, fromMyNode(node))
// Push another.
node = &MyNode{data: 43}
nodes = append(nodes, node)
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")
}
}
var stress []*MyNode
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)}
// Need to keep additional references to nodes,
// the lock-free stack is not type-safe.
stress = nil
// Push K elements randomly onto the stacks.
sum := 0
for i := 0; i < K; i++ {
sum += i
node := &MyNode{data: i}
stress = append(stress, node)
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 = nil
}
}
if cnt != K {
t.Fatalf("Wrong number of nodes %d/%d", cnt, K)
}
if sum2 != sum {
t.Fatalf("Wrong sum %d/%d", sum2, sum)
}
// Let nodes be collected now.
stress = nil
}
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