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package stm
import (
"sync"
"testing"
"time"
_ "github.com/anacrolix/envpprof"
"github.com/stretchr/testify/assert"
)
func TestDecrement(t *testing.T) {
x := NewVar(1000)
for i := 0; i < 500; i++ {
go Atomically(VoidOperation(func(tx *Tx) {
cur := tx.Get(x).(int)
tx.Set(x, cur-1)
}))
}
done := make(chan struct{})
go func() {
Atomically(VoidOperation(func(tx *Tx) {
tx.Assert(tx.Get(x) == 500)
}))
close(done)
}()
select {
case <-done:
case <-time.After(time.Second):
t.Fatal("decrement did not complete in time")
}
}
// read-only transaction aren't exempt from calling tx.verify
func TestReadVerify(t *testing.T) {
read := make(chan struct{})
x, y := NewVar(1), NewVar(2)
// spawn a transaction that writes to x
go func() {
<-read
AtomicSet(x, 3)
read <- struct{}{}
// other tx should retry, so we need to read/send again
read <- <-read
}()
// spawn a transaction that reads x, then y. The other tx will modify x in
// between the reads, causing this tx to retry.
var x2, y2 int
Atomically(VoidOperation(func(tx *Tx) {
x2 = tx.Get(x).(int)
read <- struct{}{}
<-read // wait for other tx to complete
y2 = tx.Get(y).(int)
}))
if x2 == 1 && y2 == 2 {
t.Fatal("read was not verified")
}
}
func TestRetry(t *testing.T) {
x := NewVar(10)
// spawn 10 transactions, one every 10 milliseconds. This will decrement x
// to 0 over the course of 100 milliseconds.
go func() {
for i := 0; i < 10; i++ {
time.Sleep(10 * time.Millisecond)
Atomically(VoidOperation(func(tx *Tx) {
cur := tx.Get(x).(int)
tx.Set(x, cur-1)
}))
}
}()
// Each time we read x before the above loop has finished, we need to
// retry. This should result in no more than 1 retry per transaction.
retry := 0
Atomically(VoidOperation(func(tx *Tx) {
cur := tx.Get(x).(int)
if cur != 0 {
retry++
tx.Retry()
}
}))
if retry > 10 {
t.Fatal("should have retried at most 10 times, got", retry)
}
}
func TestVerify(t *testing.T) {
// tx.verify should check more than pointer equality
type foo struct {
i int
}
x := NewVar(&foo{3})
read := make(chan struct{})
// spawn a transaction that modifies x
go func() {
Atomically(VoidOperation(func(tx *Tx) {
<-read
rx := tx.Get(x).(*foo)
rx.i = 7
tx.Set(x, rx)
}))
read <- struct{}{}
// other tx should retry, so we need to read/send again
read <- <-read
}()
// spawn a transaction that reads x, then y. The other tx will modify x in
// between the reads, causing this tx to retry.
var i int
Atomically(VoidOperation(func(tx *Tx) {
f := tx.Get(x).(*foo)
i = f.i
read <- struct{}{}
<-read // wait for other tx to complete
}))
if i == 3 {
t.Fatal("verify did not retry despite modified Var", i)
}
}
func TestSelect(t *testing.T) {
// empty Select should block forever
c := make(chan struct{})
go func() {
Atomically(Select())
c <- struct{}{}
}()
select {
case <-c:
t.Fatal("empty Select did not block forever")
case <-time.After(10 * time.Millisecond):
}
// with one arg, Select adds no effect
x := NewVar(2)
Atomically(Select(VoidOperation(func(tx *Tx) {
tx.Assert(tx.Get(x).(int) == 2)
})))
picked := Atomically(Select(
// always blocks; should never be selected
VoidOperation(func(tx *Tx) {
tx.Retry()
}),
// always succeeds; should always be selected
func(tx *Tx) interface{} {
return 2
},
// always succeeds; should never be selected
func(tx *Tx) interface{} {
return 3
},
)).(int)
assert.EqualValues(t, 2, picked)
}
func TestCompose(t *testing.T) {
nums := make([]int, 100)
fns := make([]Operation, 100)
for i := range fns {
fns[i] = func(x int) Operation {
return VoidOperation(func(*Tx) { nums[x] = x })
}(i) // capture loop var
}
Atomically(Compose(fns...))
for i := range nums {
if nums[i] != i {
t.Error("Compose failed:", nums[i], i)
}
}
}
func TestPanic(t *testing.T) {
// normal panics should escape Atomically
assert.PanicsWithValue(t, "foo", func() {
Atomically(func(*Tx) interface{} {
panic("foo")
})
})
}
func TestReadWritten(t *testing.T) {
// reading a variable written in the same transaction should return the
// previously written value
x := NewVar(3)
Atomically(VoidOperation(func(tx *Tx) {
tx.Set(x, 5)
tx.Assert(tx.Get(x).(int) == 5)
}))
}
func TestAtomicSetRetry(t *testing.T) {
// AtomicSet should cause waiting transactions to retry
x := NewVar(3)
done := make(chan struct{})
go func() {
Atomically(VoidOperation(func(tx *Tx) {
tx.Assert(tx.Get(x).(int) == 5)
}))
done <- struct{}{}
}()
time.Sleep(10 * time.Millisecond)
AtomicSet(x, 5)
select {
case <-done:
case <-time.After(time.Second):
t.Fatal("AtomicSet did not wake up a waiting transaction")
}
}
func testPingPong(t testing.TB, n int, afterHit func(string)) {
ball := NewVar(false)
doneVar := NewVar(false)
hits := NewVar(0)
ready := NewVar(true) // The ball is ready for hitting.
var wg sync.WaitGroup
bat := func(from, to interface{}, noise string) {
defer wg.Done()
for !Atomically(func(tx *Tx) interface{} {
if tx.Get(doneVar).(bool) {
return true
}
tx.Assert(tx.Get(ready).(bool))
if tx.Get(ball) == from {
tx.Set(ball, to)
tx.Set(hits, tx.Get(hits).(int)+1)
tx.Set(ready, false)
return false
}
panic(Retry)
}).(bool) {
afterHit(noise)
AtomicSet(ready, true)
}
}
wg.Add(2)
go bat(false, true, "ping!")
go bat(true, false, "pong!")
Atomically(VoidOperation(func(tx *Tx) {
tx.Assert(tx.Get(hits).(int) >= n)
tx.Set(doneVar, true)
}))
wg.Wait()
}
func TestPingPong(t *testing.T) {
testPingPong(t, 42, func(s string) { t.Log(s) })
}
|