func (f *truncFiler) WriteAt(b []byte, off int64) (n int, err error) {
rq := len(b)
n = f.totalWritten
if lim := f.limit; lim >= 0 && n+rq > lim {
over := n + rq - lim
rq -= over
rq = mathutil.Max(rq, 0)
}
if n, err = f.fake.WriteAt(b, off); err != nil {
return
}
f.totalWritten += n
if rq != 0 {
n, err := f.f.WriteAt(b[:rq], off)
if err != nil {
return n, err
}
f.realWritten += n
}
return
}
func TestRollbackFiler4(t *testing.T) {
const (
maxSize = 1e6
maxChange = maxSize/100 + 4
maxChanges = 10
maxNest = 3
)
var r *RollbackFiler
f := NewMemFiler()
checkpoint := func(sz int64) (err error) {
return f.Truncate(sz)
}
r, err := NewRollbackFiler(f, checkpoint, f)
if err != nil {
t.Fatal(err)
}
rng := rand.New(rand.NewSource(42))
ref := make([]byte, 2*maxSize)
for i := range ref {
ref[i] = byte(rng.Int())
}
var finalSize int
var fn func(int, int, []byte) (int, []byte)
fn = func(nest, inSize int, in []byte) (outSize int, out []byte) {
defer func() {
for i := outSize; i < len(out); i++ {
out[i] = 0
}
finalSize = mathutil.Max(finalSize, outSize)
}()
out = make([]byte, len(in), 2*maxSize)
copy(out, in)
if err := r.BeginUpdate(); err != nil {
t.Fatal(err)
}
for i := 0; i < maxChanges; i++ {
changeLen := rng.Intn(maxChange) + 4
changeOff := rng.Intn(maxSize * 3 / 2)
b := make([]byte, changeLen)
for i := range b {
b[i] = byte(rng.Int())
}
if n, err := r.WriteAt(b, int64(changeOff)); n != len(b) || err != nil {
t.Fatal(n, len(b), err)
}
}
if err := r.Rollback(); err != nil {
t.Fatal(err)
}
if err := r.BeginUpdate(); err != nil {
t.Fatal(err)
}
for i := 0; i < maxChanges; i++ {
changeLen := rng.Intn(maxChange) + 4
changeOff := rng.Intn(maxSize * 3 / 2)
b := make([]byte, changeLen)
for i := range b {
b[i] = byte(rng.Int())
}
if n, err := r.WriteAt(b, int64(changeOff)); n != len(b) || err != nil {
t.Fatal(n, len(b), err)
}
copy(out[changeOff:], b)
copy(ref[changeOff:], b)
}
newSize := rng.Intn(maxSize*3/2) + 4
if nest == maxNest {
if err := r.EndUpdate(); err != nil {
t.Fatal(err)
}
return newSize, out
}
outSize, out = fn(nest+1, newSize, out)
if err := r.EndUpdate(); err != nil {
t.Fatal(err)
}
return
}
sz, result := fn(0, maxSize, ref)
if g, e := sz, finalSize; g != e {
t.Fatal(err)
}
g, e := result[:sz], ref[:sz]
if !bytes.Equal(g, e) {
if len(g) == len(e) {
x := make([]byte, len(g))
for i := range x {
if g[i] != e[i] {
x[i] = 'X'
}
}
//t.Logf("Data diff\n%s", hex.Dump(x))
}
//t.Fatalf("Data don't match: got\n%sexp:\n%s", hex.Dump(g), hex.Dump(e))
t.Fatalf("Data don't match")
}
}
func encUint(n uint64, b *[]byte) {
bits := mathutil.Max(1, mathutil.BitLenUint64(n))
encUintPrefix(gbUintP1+byte((bits-1)>>3), n, b)
}