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// Copyright 2013 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 sync_test
import (
"runtime"
"runtime/debug"
. "sync"
"sync/atomic"
"testing"
"time"
"unsafe"
)
func TestPool(t *testing.T) {
// disable GC so we can control when it happens.
defer debug.SetGCPercent(debug.SetGCPercent(-1))
var p Pool
if p.Get() != nil {
t.Fatal("expected empty")
}
p.Put("a")
p.Put("b")
if g := p.Get(); g != "b" {
t.Fatalf("got %#v; want b", g)
}
if g := p.Get(); g != "a" {
t.Fatalf("got %#v; want a", g)
}
if g := p.Get(); g != nil {
t.Fatalf("got %#v; want nil", g)
}
p.Put("c")
debug.SetGCPercent(100) // to allow following GC to actually run
runtime.GC()
if g := p.Get(); g != nil {
t.Fatalf("got %#v; want nil after GC", g)
}
}
func TestPoolNew(t *testing.T) {
// disable GC so we can control when it happens.
defer debug.SetGCPercent(debug.SetGCPercent(-1))
i := 0
p := Pool{
New: func() interface{} {
i++
return i
},
}
if v := p.Get(); v != 1 {
t.Fatalf("got %v; want 1", v)
}
if v := p.Get(); v != 2 {
t.Fatalf("got %v; want 2", v)
}
p.Put(42)
if v := p.Get(); v != 42 {
t.Fatalf("got %v; want 42", v)
}
if v := p.Get(); v != 3 {
t.Fatalf("got %v; want 3", v)
}
}
// Test that Pool does not hold pointers to previously cached
// resources
func TestPoolGC(t *testing.T) {
var p Pool
var fin uint32
const N = 100
for i := 0; i < N; i++ {
v := new(int)
runtime.SetFinalizer(v, func(vv *int) {
atomic.AddUint32(&fin, 1)
})
p.Put(v)
}
for i := 0; i < N; i++ {
p.Get()
}
for i := 0; i < 5; i++ {
runtime.GC()
time.Sleep(time.Millisecond)
// 1 pointer can remain on stack or elsewhere
if atomic.LoadUint32(&fin) >= N-1 {
return
}
// gccgo has a less precise heap.
if runtime.Compiler == "gccgo" && atomic.LoadUint32(&fin) >= N-5 {
return
}
}
t.Fatalf("only %v out of %v resources are finalized",
atomic.LoadUint32(&fin), N)
}
func TestPoolStress(t *testing.T) {
const P = 10
N := int(1e6)
if testing.Short() {
N /= 100
}
var p Pool
done := make(chan bool)
for i := 0; i < P; i++ {
go func() {
var v interface{} = 0
for j := 0; j < N; j++ {
if v == nil {
v = 0
}
p.Put(v)
v = p.Get()
if v != nil && v.(int) != 0 {
t.Fatalf("expect 0, got %v", v)
}
}
done <- true
}()
}
for i := 0; i < P; i++ {
<-done
}
}
func BenchmarkPool(b *testing.B) {
procs := runtime.GOMAXPROCS(-1)
var dec func() bool
if unsafe.Sizeof(b.N) == 8 {
n := int64(b.N)
dec = func() bool {
return atomic.AddInt64(&n, -1) >= 0
}
} else {
n := int32(b.N)
dec = func() bool {
return atomic.AddInt32(&n, -1) >= 0
}
}
var p Pool
var wg WaitGroup
for i := 0; i < procs; i++ {
wg.Add(1)
go func() {
defer wg.Done()
for dec() {
p.Put(1)
p.Get()
}
}()
}
wg.Wait()
}
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