// This will deduplicate a buffer of zeros to an indexed stream
func ExampleNewReader() {
// Create data we can read.
var idx, data bytes.Buffer
input := bytes.NewBuffer(make([]byte, 50000))
w, _ := dedup.NewWriter(&idx, &data, dedup.ModeFixed, 1000, 0)
_, _ = io.Copy(w, input)
_ = w.Close()
// Create a new reader.
r, err := dedup.NewReader(&idx, &data)
if err != nil {
panic(err)
}
// Inspect how much memory it will use.
fmt.Println("Memory use:", r.MaxMem())
var dst bytes.Buffer
// Read everything
_, err = io.Copy(&dst, r)
if err != nil && err != io.EOF {
panic(err)
}
// Let us inspect what was written:
fmt.Println("Returned data length:", dst.Len())
fmt.Println("Everything zero:", 0 == bytes.Compare(dst.Bytes(), make([]byte, 50000)))
// OUTPUT: Memory use: 1000
// Returned data length: 50000
// Everything zero: true
}
func TestReader(t *testing.T) {
idx := bytes.Buffer{}
data := bytes.Buffer{}
const totalinput = 10<<20 + 65
input := getBufferSize(totalinput)
const size = 64 << 10
b := input.Bytes()
// Create some duplicates
for i := 0; i < 50; i++ {
// Read from 10 first blocks
src := b[(i%10)*size : (i%10)*size+size]
// Write into the following ones
dst := b[(10+i)*size : (i+10)*size+size]
copy(dst, src)
}
input = bytes.NewBuffer(b)
w, err := dedup.NewWriter(&idx, &data, dedup.ModeFixed, size, 0)
if err != nil {
t.Fatal(err)
}
io.Copy(w, input)
err = w.Close()
if err != nil {
t.Fatal(err)
}
t.Log("Fixed Index size:", idx.Len())
t.Log("Fixed Data size:", data.Len(), "-", data.Len()*100/totalinput, "%")
r, err := dedup.NewReader(&idx, &data)
if err != nil {
t.Fatal(err)
}
t.Log("Maximum estimated memory:", r.MaxMem(), "bytes")
out, err := ioutil.ReadAll(r)
if err != io.EOF && err != nil {
t.Fatal(err)
}
if len(b) != len(out) {
t.Fatalf("Expected len %d, got %d", len(b), len(out))
}
if bytes.Compare(b, out) != 0 {
t.Fatal("Output mismatch")
}
err = r.Close()
if err != nil {
t.Fatal(err)
}
blocks := r.BlockSizes()
for _, s := range blocks[:len(blocks)-1] {
if s != size {
t.Fatal("wrong size, expected", size, "got", s)
}
}
}
// Indexed stream, 10MB input, 1K blocks
func BenchmarkReader1K(t *testing.B) {
idx := &bytes.Buffer{}
data := &bytes.Buffer{}
const totalinput = 10 << 20
input := getBufferSize(totalinput)
const size = 1 << 10
b := input.Bytes()
// Create some duplicates
for i := 0; i < 500; i++ {
// Read from 10 first blocks
src := b[(i%10)*size : (i%10)*size+size]
// Write into the following ones
dst := b[(10+i)*size : (i+10)*size+size]
copy(dst, src)
}
input = bytes.NewBuffer(b)
w, err := dedup.NewWriter(idx, data, dedup.ModeFixed, size, 0)
if err != nil {
t.Fatal(err)
}
_, err = io.Copy(w, input)
if err != nil {
t.Fatal(err)
}
err = w.Close()
if err != nil {
t.Fatal(err)
}
index := idx.Bytes()
alldata := data.Bytes()
t.ResetTimer()
t.SetBytes(totalinput)
for i := 0; i < t.N; i++ {
idx := bytes.NewBuffer(index)
data := bytes.NewBuffer(alldata)
r, err := dedup.NewReader(idx, data)
if err != nil {
t.Fatal(err)
}
n, err := io.Copy(ioutil.Discard, r)
if err != nil && err != io.EOF {
t.Fatal(err)
}
if n != int64(len(b)) {
t.Fatal("read was short, expected", len(b), "was", n)
}
err = r.Close()
if err != nil {
t.Fatal(err)
}
}
}
func TestFixedWriterLimit(t *testing.T) {
idx := bytes.Buffer{}
data := bytes.Buffer{}
const totalinput = 10 << 20
const limit = 9
input := getBufferSize(totalinput)
const size = 64 << 10
b := input.Bytes()
// Create some duplicates
for i := 0; i < 50; i++ {
// Read from 10 first blocks
src := b[(i%10)*size : (i%10)*size+size]
// Write into the following ones
dst := b[(10+50-i)*size : (10+50-i)*size+size]
copy(dst, src)
}
input = bytes.NewBuffer(b)
w, err := dedup.NewWriter(&idx, &data, dedup.ModeFixed, size, limit*size)
if err != nil {
t.Fatal(err)
}
io.Copy(w, input)
err = w.Close()
if err != nil {
t.Fatal(err)
}
removed := ((totalinput) - data.Len()) / size
t.Log("Index size:", idx.Len())
t.Log("Data size:", data.Len())
t.Log("Removed", removed, "blocks")
// We should get at least 50 blocks
if removed > 10 {
t.Fatal("it did not appear to respect the limit")
}
if removed < 8 {
t.Fatal("removed too many blocks")
}
r, err := dedup.NewReader(&idx, &data)
if err != nil {
t.Fatal(err)
}
useBlocks := r.MaxMem() / size
if useBlocks > 9 {
t.Fatal("Uses too much memory, expected", limit, "got", useBlocks)
}
t.Log("Maximum estimated use:", r.MaxMem(), "bytes,", useBlocks, "blocks")
r.Close()
}
func TestReaderWriteTo(t *testing.T) {
idx := bytes.Buffer{}
data := bytes.Buffer{}
const totalinput = 10<<20 + 65
input := getBufferSize(totalinput)
const size = 64 << 10
b := input.Bytes()
// Create some duplicates
for i := 0; i < 50; i++ {
// Read from 10 first blocks
src := b[(i%10)*size : (i%10)*size+size]
// Write into the following ones
dst := b[(10+i)*size : (i+10)*size+size]
copy(dst, src)
}
input = bytes.NewBuffer(b)
w, err := dedup.NewWriter(&idx, &data, dedup.ModeFixed, size, 0)
if err != nil {
t.Fatal(err)
}
io.Copy(w, input)
err = w.Close()
if err != nil {
t.Fatal(err)
}
r, err := dedup.NewReader(&idx, &data)
if err != nil {
t.Fatal(err)
}
dst := &bytes.Buffer{}
n, err := r.WriteTo(dst)
if err != io.EOF && err != nil {
t.Fatal(err)
}
if len(b) != int(n) {
t.Errorf("Write count, expected n %d, got %d", len(b), n)
}
out := dst.Bytes()
if len(b) != len(out) {
t.Fatalf("Expected len %d, got %d", len(b), len(out))
}
if len(b) != len(out) {
t.Fatalf("Expected len %d, got %d", len(b), len(out))
}
if bytes.Compare(b, out) != 0 {
t.Fatal("Output mismatch")
}
err = r.Close()
if err != nil {
t.Fatal(err)
}
blocks := r.BlockSizes()
for _, s := range blocks[:len(blocks)-1] {
if s != size {
t.Fatal("wrong size, expected", size, "got", s)
}
}
}
func TestDynamicRoundtrip(t *testing.T) {
idx := bytes.Buffer{}
data := bytes.Buffer{}
const totalinput = 10<<20 + 65
input := getBufferSize(totalinput)
const size = 64 << 10
b := input.Bytes()
// Create some duplicates
for i := 0; i < 50; i++ {
// Read from 10 first blocks
src := b[(i%10)*size : (i%10)*size+size]
// Write into the following ones
dst := b[(10+i)*size : (i+10)*size+size]
copy(dst, src)
}
input = bytes.NewBuffer(b)
w, err := dedup.NewWriter(&idx, &data, dedup.ModeDynamic, size, 0)
if err != nil {
t.Fatal(err)
}
io.Copy(w, input)
err = w.Close()
if err != nil {
t.Fatal(err)
}
t.Log("Dynamic Index size:", idx.Len())
t.Log("Dynamic Data size:", data.Len())
r, err := dedup.NewReader(&idx, &data)
if err != nil {
t.Fatal(err)
}
t.Log("Maximum estimated memory:", r.MaxMem(), "bytes")
blocks := r.BlockSizes()
avg := 0
for _, v := range blocks {
if v > size {
t.Fatal("too big block returned, should not be >", size, "was", v)
}
avg += v
}
t.Log("Average block size:", avg/len(blocks), "bytes")
out, err := ioutil.ReadAll(r)
if err != io.EOF && err != nil {
t.Fatal(err)
}
if len(b) != len(out) {
t.Fatalf("Expected len %d, got %d", len(b), len(out))
}
if bytes.Compare(b, out) != 0 {
t.Fatal("Output mismatch")
}
err = r.Close()
if err != nil {
t.Fatal(err)
}
}