Golang KVStore.Reader方法代碼示例

func CommonTestMerge(t *testing.T, s store.KVStore) {

	testKey := []byte("k1")

	data := []struct {
		key []byte
		val []byte
	}{
		{testKey, encodeUint64(1)},
		{testKey, encodeUint64(1)},
	}

	// open a writer
	writer, err := s.Writer()
	if err != nil {
		t.Fatal(err)
	}

	// write the data
	batch := writer.NewBatch()
	for _, row := range data {
		batch.Merge(row.key, row.val)
	}
	err = writer.ExecuteBatch(batch)
	if err != nil {
		t.Fatal(err)
	}

	// close the writer
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	// open a reader
	reader, err := s.Reader()
	if err != nil {
		t.Fatal(err)
	}

	// read key
	returnedVal, err := reader.Get(testKey)
	if err != nil {
		t.Fatal(err)
	}

	// check the value
	mergedval := binary.LittleEndian.Uint64(returnedVal)
	if mergedval != 2 {
		t.Errorf("expected 2, got %d", mergedval)
	}

	// close the reader
	err = reader.Close()
	if err != nil {
		t.Fatal(err)
	}

}

// NullTestKVStore has very different expectations
// compared to CommonTestKVStore
func NullTestKVStore(t *testing.T, s store.KVStore) {

	writer, err := s.Writer()
	if err != nil {
		t.Error(err)
	}

	batch := writer.NewBatch()
	batch.Set([]byte("b"), []byte("val-b"))
	batch.Set([]byte("c"), []byte("val-c"))
	batch.Set([]byte("d"), []byte("val-d"))
	batch.Set([]byte("e"), []byte("val-e"))
	batch.Set([]byte("f"), []byte("val-f"))
	batch.Set([]byte("g"), []byte("val-g"))
	batch.Set([]byte("h"), []byte("val-h"))
	batch.Set([]byte("i"), []byte("val-i"))
	batch.Set([]byte("j"), []byte("val-j"))

	err = writer.ExecuteBatch(batch)
	if err != nil {
		t.Fatal(err)
	}
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	reader, err := s.Reader()
	if err != nil {
		t.Error(err)
	}
	defer func() {
		err := reader.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()
	it := reader.RangeIterator([]byte("b"), nil)
	key, val, valid := it.Current()
	if valid {
		t.Fatalf("valid true, expected false")
	}
	if key != nil {
		t.Fatalf("expected key nil, got %s", key)
	}
	if val != nil {
		t.Fatalf("expected value nil, got %s", val)
	}

	err = it.Close()
	if err != nil {
		t.Fatal(err)
	}

	err = s.Close()
	if err != nil {
		t.Fatal(err)
	}
}

func CommonTestKVCrud(t *testing.T, s store.KVStore) {

	writer, err := s.Writer()
	if err != nil {
		t.Error(err)
	}

	batch := writer.NewBatch()
	batch.Set([]byte("a"), []byte("val-a"))
	batch.Set([]byte("z"), []byte("val-z"))
	batch.Delete([]byte("z"))
	err = writer.ExecuteBatch(batch)
	if err != nil {
		t.Fatal(err)
	}

	batch.Reset()

	batch.Set([]byte("b"), []byte("val-b"))
	batch.Set([]byte("c"), []byte("val-c"))
	batch.Set([]byte("d"), []byte("val-d"))
	batch.Set([]byte("e"), []byte("val-e"))
	batch.Set([]byte("f"), []byte("val-f"))
	batch.Set([]byte("g"), []byte("val-g"))
	batch.Set([]byte("h"), []byte("val-h"))
	batch.Set([]byte("i"), []byte("val-i"))
	batch.Set([]byte("j"), []byte("val-j"))

	err = writer.ExecuteBatch(batch)
	if err != nil {
		t.Fatal(err)
	}
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	reader, err := s.Reader()
	if err != nil {
		t.Error(err)
	}
	defer func() {
		err := reader.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()
	it := reader.RangeIterator([]byte("b"), nil)
	key, val, valid := it.Current()
	if !valid {
		t.Fatalf("valid false, expected true")
	}
	if string(key) != "b" {
		t.Fatalf("expected key b, got %s", key)
	}
	if string(val) != "val-b" {
		t.Fatalf("expected value val-b, got %s", val)
	}

	it.Next()
	key, val, valid = it.Current()
	if !valid {
		t.Fatalf("valid false, expected true")
	}
	if string(key) != "c" {
		t.Fatalf("expected key c, got %s", key)
	}
	if string(val) != "val-c" {
		t.Fatalf("expected value val-c, got %s", val)
	}

	it.Seek([]byte("i"))
	key, val, valid = it.Current()
	if !valid {
		t.Fatalf("valid false, expected true")
	}
	if string(key) != "i" {
		t.Fatalf("expected key i, got %s", key)
	}
	if string(val) != "val-i" {
		t.Fatalf("expected value val-i, got %s", val)
	}

	err = it.Close()
	if err != nil {
		t.Fatal(err)
	}
}

func CommonTestReaderIsolation(t *testing.T, s store.KVStore) {
	// insert a kv pair
	writer, err := s.Writer()
	if err != nil {
		t.Error(err)
	}
	err = writer.Set([]byte("a"), []byte("val-a"))
	if err != nil {
		t.Fatal(err)
	}

	// **************************************************
	// this is a hack to try to pre-emptively overflow
	// boltdb writes *MAY* block a long reader
	// in particular, if the write requires additional
	// allocation, it must acquire the same lock as
	// the reader, thus cannot continue until that
	// reader is closed.
	// in general this is not a problem for bleve
	// (though it may affect performance in some cases)
	// but it is a problem for this test which attemps
	// to easily verify that readers are isolated
	// this hack writes enough initial data such that
	// the subsequent writes do not require additional
	// space
	hackSize := 1000
	for i := 0; i < hackSize; i++ {
		k := fmt.Sprintf("x%d", i)
		err = writer.Set([]byte(k), []byte("filler"))
		if err != nil {
			t.Fatal(err)
		}
	}
	// **************************************************

	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	// create an isolated reader
	reader, err := s.Reader()
	if err != nil {
		t.Error(err)
	}
	defer func() {
		err := reader.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()

	// verify that we see the value already inserted
	val, err := reader.Get([]byte("a"))
	if err != nil {
		t.Error(err)
	}
	if !reflect.DeepEqual(val, []byte("val-a")) {
		t.Errorf("expected val-a, got nil")
	}

	// verify that an iterator sees it
	count := 0
	it := reader.Iterator([]byte{0})
	defer func() {
		err := it.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()
	for it.Valid() {
		it.Next()
		count++
	}
	if count != hackSize+1 {
		t.Errorf("expected iterator to see 1, saw %d", count)
	}

	// add something after the reader was created
	writer, err = s.Writer()
	if err != nil {
		t.Error(err)
	}
	err = writer.Set([]byte("b"), []byte("val-b"))
	if err != nil {
		t.Fatal(err)
	}
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	// ensure that a newer reader sees it
	newReader, err := s.Reader()
	if err != nil {
		t.Error(err)
	}
	defer func() {
		err := newReader.Close()
		if err != nil {
//.........這裏部分代碼省略.........

func CommonTestReaderIsolation(t *testing.T, s store.KVStore) {
	// insert a kv pair
	writer, err := s.Writer()
	if err != nil {
		t.Error(err)
	}
	err = writer.Set([]byte("a"), []byte("val-a"))
	if err != nil {
		t.Fatal(err)
	}
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	// create an isolated reader
	reader, err := s.Reader()
	if err != nil {
		t.Error(err)
	}
	defer func() {
		err := reader.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()

	// verify that we see the value already inserted
	val, err := reader.Get([]byte("a"))
	if err != nil {
		t.Error(err)
	}
	if !reflect.DeepEqual(val, []byte("val-a")) {
		t.Errorf("expected val-a, got nil")
	}

	// verify that an iterator sees it
	count := 0
	it := reader.Iterator([]byte{0})
	defer func() {
		err := it.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()
	for it.Valid() {
		it.Next()
		count++
	}
	if count != 1 {
		t.Errorf("expected iterator to see 1, saw %d", count)
	}

	// add something after the reader was created
	writer, err = s.Writer()
	if err != nil {
		t.Error(err)
	}
	err = writer.Set([]byte("b"), []byte("val-b"))
	if err != nil {
		t.Fatal(err)
	}
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	// ensure that a newer reader sees it
	newReader, err := s.Reader()
	if err != nil {
		t.Error(err)
	}
	defer func() {
		err := newReader.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()
	val, err = newReader.Get([]byte("b"))
	if err != nil {
		t.Error(err)
	}
	if !reflect.DeepEqual(val, []byte("val-b")) {
		t.Errorf("expected val-b, got nil")
	}

	// ensure that the director iterator sees it
	count = 0
	it2 := newReader.Iterator([]byte{0})
	defer func() {
		err := it2.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()
	for it2.Valid() {
		it2.Next()
		count++
	}
	if count != 2 {
//.........這裏部分代碼省略.........

func CommonTestPrefixIterator(t *testing.T, s store.KVStore) {

	data := []testRow{
		{[]byte("apple"), []byte("val")},
		{[]byte("cat1"), []byte("val")},
		{[]byte("cat2"), []byte("val")},
		{[]byte("cat3"), []byte("val")},
		{[]byte("dog1"), []byte("val")},
		{[]byte("dog2"), []byte("val")},
		{[]byte("dog4"), []byte("val")},
		{[]byte("elephant"), []byte("val")},
	}

	expectedCats := [][]byte{
		[]byte("cat1"),
		[]byte("cat2"),
		[]byte("cat3"),
	}

	expectedDogs := [][]byte{
		[]byte("dog1"),
		// we seek to "dog3" and ensure it skips over "dog2"
		// but still finds "dog4" even though there was no "dog3"
		[]byte("dog4"),
	}

	err := batchWriteRows(s, data)
	if err != nil {
		t.Fatal(err)
	}

	// open a reader
	reader, err := s.Reader()
	if err != nil {
		t.Fatal(err)
	}

	// get a prefix reader
	cats := make([][]byte, 0)
	iter := reader.PrefixIterator([]byte("cat"))
	for iter.Valid() {
		// if we want to keep bytes from iteration we must copy
		k := iter.Key()
		copyk := make([]byte, len(k))
		copy(copyk, k)
		cats = append(cats, copyk)
		iter.Next()
	}
	err = iter.Close()
	if err != nil {
		t.Fatal(err)
	}

	// check that we found all the cats
	if !reflect.DeepEqual(cats, expectedCats) {
		t.Fatalf("expected cats %v, got %v", expectedCats, cats)
	}

	// get a prefix reader
	dogs := make([][]byte, 0)
	iter = reader.PrefixIterator([]byte("dog"))
	for iter.Valid() {
		// if we want to keep bytes from iteration we must copy
		k := iter.Key()
		copyk := make([]byte, len(k))
		copy(copyk, k)
		dogs = append(dogs, copyk)
		if len(dogs) < 2 {
			iter.Seek([]byte("dog3"))
		} else {
			iter.Next()
		}
	}
	err = iter.Close()
	if err != nil {
		t.Fatal(err)
	}

	// check that we found the expected dogs
	if !reflect.DeepEqual(dogs, expectedDogs) {
		t.Fatalf("expected dogs %v, got %v", expectedDogs, dogs)
	}

	// close the reader
	err = reader.Close()
	if err != nil {
		t.Fatal(err)
	}
}

func CommonTestRangeIteratorSeek(t *testing.T, s store.KVStore) {

	data := []testRow{
		{[]byte("a1"), []byte("val")},
		{[]byte("b1"), []byte("val")},
		{[]byte("c1"), []byte("val")},
		{[]byte("d1"), []byte("val")},
		{[]byte("e1"), []byte("val")},
	}

	err := batchWriteRows(s, data)
	if err != nil {
		t.Fatal(err)
	}

	// open a reader
	reader, err := s.Reader()
	if err != nil {
		t.Fatal(err)
	}

	// get an iterator on a central subset of the data
	start := []byte("b1")
	end := []byte("d1")
	iter := reader.RangeIterator(start, end)

	// seek before, at and after every possible key
	targets := [][]byte{}
	for _, row := range data {
		prefix := string(row.key[:1])
		targets = append(targets, []byte(prefix+"0"))
		targets = append(targets, []byte(prefix+"1"))
		targets = append(targets, []byte(prefix+"2"))
	}
	for _, target := range targets {
		found := []string{}
		for iter.Seek(target); iter.Valid(); iter.Next() {
			found = append(found, string(iter.Key()))
			if len(found) > len(data) {
				t.Fatalf("enumerated more than data keys after seeking to %s",
					string(target))
			}
		}
		wanted := []string{}
		for _, row := range data {
			if bytes.Compare(row.key, start) < 0 ||
				bytes.Compare(row.key, target) < 0 ||
				bytes.Compare(row.key, end) >= 0 {
				continue
			}
			wanted = append(wanted, string(row.key))
		}
		fs := strings.Join(found, ", ")
		ws := strings.Join(wanted, ", ")
		if fs != ws {
			t.Fatalf("iterating from %s returned [%s] instead of [%s]",
				string(target), fs, ws)
		}
	}

	err = iter.Close()
	if err != nil {
		t.Fatal(err)
	}

	if err != nil {
		t.Fatal(err)
	}

	// close the reader
	err = reader.Close()
	if err != nil {
		t.Fatal(err)
	}
}

func CommonTestRangeIterator(t *testing.T, s store.KVStore) {

	data := []testRow{
		{[]byte("a1"), []byte("val")},
		{[]byte("b1"), []byte("val")},
		{[]byte("b2"), []byte("val")},
		{[]byte("b3"), []byte("val")},
		{[]byte("c1"), []byte("val")},
		{[]byte("c2"), []byte("val")},
		{[]byte("c4"), []byte("val")},
		{[]byte("d1"), []byte("val")},
	}

	expectedAll := make([][]byte, 0)
	expectedBToC := make([][]byte, 0)
	expectedCToDSeek3 := make([][]byte, 0)
	expectedCToEnd := make([][]byte, 0)
	for _, row := range data {
		expectedAll = append(expectedAll, row.key)
		if bytes.HasPrefix(row.key, []byte("b")) {
			expectedBToC = append(expectedBToC, row.key)
		}
		if bytes.HasPrefix(row.key, []byte("c")) && !bytes.HasSuffix(row.key, []byte("2")) {
			expectedCToDSeek3 = append(expectedCToDSeek3, row.key)
		}
		if bytes.Compare(row.key, []byte("c")) > 0 {
			expectedCToEnd = append(expectedCToEnd, row.key)
		}
	}

	err := batchWriteRows(s, data)
	if err != nil {
		t.Fatal(err)
	}

	// open a reader
	reader, err := s.Reader()
	if err != nil {
		t.Fatal(err)
	}

	// get a range iterator (all)
	all := make([][]byte, 0)
	iter := reader.RangeIterator(nil, nil)
	for iter.Valid() {
		// if we want to keep bytes from iteration we must copy
		k := iter.Key()
		copyk := make([]byte, len(k))
		copy(copyk, k)
		all = append(all, copyk)
		iter.Next()
	}
	err = iter.Close()
	if err != nil {
		t.Fatal(err)
	}

	// check that we found all
	if !reflect.DeepEqual(all, expectedAll) {
		t.Fatalf("expected all %v, got %v", expectedAll, all)
	}

	// get range iterator from b - c
	bToC := make([][]byte, 0)
	iter = reader.RangeIterator([]byte("b"), []byte("c"))
	for iter.Valid() {
		// if we want to keep bytes from iteration we must copy
		k := iter.Key()
		copyk := make([]byte, len(k))
		copy(copyk, k)
		bToC = append(bToC, copyk)
		iter.Next()
	}
	err = iter.Close()
	if err != nil {
		t.Fatal(err)
	}

	// check that we found b-c
	if !reflect.DeepEqual(bToC, expectedBToC) {
		t.Fatalf("expected b-c %v, got %v", expectedBToC, bToC)
	}

	// get range iterator from c - d, but seek to 'c3'
	cToDSeek3 := make([][]byte, 0)
	iter = reader.RangeIterator([]byte("c"), []byte("d"))
	for iter.Valid() {
		// if we want to keep bytes from iteration we must copy
		k := iter.Key()
		copyk := make([]byte, len(k))
		copy(copyk, k)
		cToDSeek3 = append(cToDSeek3, copyk)
		if len(cToDSeek3) < 2 {
			iter.Seek([]byte("c3"))
		} else {
			iter.Next()
		}
	}
	err = iter.Close()
	if err != nil {
//.........這裏部分代碼省略.........

func CommonTestPrefixIteratorSeek(t *testing.T, s store.KVStore) {

	data := []testRow{
		{[]byte("a"), []byte("val")},
		{[]byte("b1"), []byte("val")},
		{[]byte("b2"), []byte("val")},
		{[]byte("b3"), []byte("val")},
		{[]byte("c"), []byte("val")},
	}

	err := batchWriteRows(s, data)
	if err != nil {
		t.Fatal(err)
	}

	// open a reader
	reader, err := s.Reader()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err := reader.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()

	// get an iterator on a central subset of the data
	iter := reader.PrefixIterator([]byte("b"))
	defer func() {
		err := iter.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()

	// check that all keys have prefix
	found := []string{}
	for ; iter.Valid(); iter.Next() {
		found = append(found, string(iter.Key()))
	}
	for _, f := range found {
		if !strings.HasPrefix(f, "b") {
			t.Errorf("got key '%s' that doesn't have correct prefix", f)
		}
	}
	if len(found) != 3 {
		t.Errorf("expected 3 keys with prefix, got %d", len(found))
	}

	// now try to seek before the prefix and repeat
	found = []string{}
	for iter.Seek([]byte("a")); iter.Valid(); iter.Next() {
		found = append(found, string(iter.Key()))
	}
	for _, f := range found {
		if !strings.HasPrefix(f, "b") {
			t.Errorf("got key '%s' that doesn't have correct prefix", f)
		}
	}
	if len(found) != 3 {
		t.Errorf("expected 3 keys with prefix, got %d", len(found))
	}

	// now try to seek after the prefix and repeat
	found = []string{}
	for iter.Seek([]byte("c")); iter.Valid(); iter.Next() {
		found = append(found, string(iter.Key()))
	}
	for _, f := range found {
		if !strings.HasPrefix(f, "b") {
			t.Errorf("got key '%s' that doesn't have correct prefix", f)
		}
	}
	if len(found) != 0 {
		t.Errorf("expected 0 keys with prefix, got %d", len(found))
	}

}

// CommonTestReaderOwnsGetBytes attempts to mutate the returned bytes
// first, while the reader is still open, second after that reader is
// closed, then the original key is read again, to ensure these
// modifications did not cause panic, or mutate the stored value
func CommonTestReaderOwnsGetBytes(t *testing.T, s store.KVStore) {

	originalKey := []byte("key")
	originalVal := []byte("val")

	// open a writer
	writer, err := s.Writer()
	if err != nil {
		t.Fatal(err)
	}

	// write key/val
	batch := writer.NewBatch()
	batch.Set(originalKey, originalVal)
	err = writer.ExecuteBatch(batch)
	if err != nil {
		t.Fatal(err)
	}

	// close the writer
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	// open a reader
	reader, err := s.Reader()
	if err != nil {
		t.Fatal(err)
	}

	// read key
	returnedVal, err := reader.Get(originalKey)
	if err != nil {
		t.Fatal(err)
	}

	// check that it is the expected value
	if !reflect.DeepEqual(returnedVal, originalVal) {
		t.Fatalf("expected value: %v for '%s', got %v", originalVal, originalKey, returnedVal)
	}

	// mutate the returned value with reader still open
	for i := range returnedVal {
		returnedVal[i] = '1'
	}

	// read the key again
	returnedVal2, err := reader.Get(originalKey)
	if err != nil {
		t.Fatal(err)
	}

	// check that it is the expected value
	if !reflect.DeepEqual(returnedVal2, originalVal) {
		t.Fatalf("expected value: %v for '%s', got %v", originalVal, originalKey, returnedVal2)
	}

	// close the reader
	err = reader.Close()
	if err != nil {
		t.Fatal(err)
	}

	// mutate the original returned value again
	for i := range returnedVal {
		returnedVal[i] = '2'
	}

	// open another reader
	reader, err = s.Reader()
	if err != nil {
		t.Fatal(err)
	}

	// read the key again
	returnedVal3, err := reader.Get(originalKey)
	if err != nil {
		t.Fatal(err)
	}

	// check that it is the expected value
	if !reflect.DeepEqual(returnedVal3, originalVal) {
		t.Fatalf("expected value: %v for '%s', got %v", originalVal, originalKey, returnedVal3)
	}

	// close the reader
	err = reader.Close()
	if err != nil {
		t.Fatal(err)
	}

	// finally check that the value we mutated still has what we set it to
	for i := range returnedVal {
		if returnedVal[i] != '2' {
			t.Errorf("expected byte to be '2', got %v", returnedVal[i])
//.........這裏部分代碼省略.........

func CommonTestWriterOwnsBytes(t *testing.T, s store.KVStore) {

	keyBuffer := make([]byte, 5)
	valBuffer := make([]byte, 5)

	// open a writer
	writer, err := s.Writer()
	if err != nil {
		t.Fatal(err)
	}

	// write key/val pairs reusing same buffer
	batch := writer.NewBatch()
	for i := 0; i < 10; i++ {
		keyBuffer[0] = 'k'
		keyBuffer[1] = 'e'
		keyBuffer[2] = 'y'
		keyBuffer[3] = '-'
		keyBuffer[4] = byte('0' + i)
		valBuffer[0] = 'v'
		valBuffer[1] = 'a'
		valBuffer[2] = 'l'
		valBuffer[3] = '-'
		valBuffer[4] = byte('0' + i)
		batch.Set(keyBuffer, valBuffer)
	}
	err = writer.ExecuteBatch(batch)
	if err != nil {
		t.Fatal(err)
	}

	// close the writer
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	// open a reader
	reader, err := s.Reader()
	if err != nil {
		t.Fatal(err)
	}

	// check that we can read back what we expect
	allks := make([][]byte, 0)
	allvs := make([][]byte, 0)
	iter := reader.RangeIterator(nil, nil)
	for iter.Valid() {
		// if we want to keep bytes from iteration we must copy
		k := iter.Key()
		copyk := make([]byte, len(k))
		copy(copyk, k)
		allks = append(allks, copyk)
		v := iter.Key()
		copyv := make([]byte, len(v))
		copy(copyv, v)
		allvs = append(allvs, copyv)
		iter.Next()
	}
	err = iter.Close()
	if err != nil {
		t.Fatal(err)
	}

	if len(allks) != 10 {
		t.Fatalf("expected 10 k/v pairs, got %d", len(allks))
	}
	for i, key := range allks {
		val := allvs[i]
		if !bytes.HasSuffix(key, []byte{byte('0' + i)}) {
			t.Errorf("expected key %v to end in %d", key, []byte{byte('0' + i)})
		}
		if !bytes.HasSuffix(val, []byte{byte('0' + i)}) {
			t.Errorf("expected val %v to end in %d", val, []byte{byte('0' + i)})
		}
	}

	// close the reader
	err = reader.Close()
	if err != nil {
		t.Fatal(err)
	}

	// open a writer
	writer, err = s.Writer()
	if err != nil {
		t.Fatal(err)
	}

	// now delete using same approach
	batch = writer.NewBatch()
	for i := 0; i < 10; i++ {
		keyBuffer[0] = 'k'
		keyBuffer[1] = 'e'
		keyBuffer[2] = 'y'
		keyBuffer[3] = '-'
		keyBuffer[4] = byte('0' + i)
		batch.Delete(keyBuffer)
	}
	err = writer.ExecuteBatch(batch)
//.........這裏部分代碼省略.........

func CommonTestKVStoreIterator(t *testing.T, s store.KVStore) {

	writer, err := s.Writer()
	if err != nil {
		t.Error(err)
	}

	data := []struct {
		k []byte
		v []byte
	}{
		{[]byte("t\x09\x00paint\xff/sponsor/gold/thumbtack/"), []byte("a")},
		{[]byte("t\x09\x00party\xff/sponsor/gold/thumbtack/"), []byte("a")},
		{[]byte("t\x09\x00personal\xff/sponsor/gold/thumbtack/"), []byte("a")},
		{[]byte("t\x09\x00plan\xff/sponsor/gold/thumbtack/"), []byte("a")},
	}

	batch := writer.NewBatch()
	for _, d := range data {
		batch.Set(d.k, d.v)
	}

	err = batch.Execute()
	if err != nil {
		t.Fatal(err)
	}
	err = writer.Close()
	if err != nil {
		t.Fatal(err)
	}

	reader, err := s.Reader()
	if err != nil {
		t.Error(err)
	}
	defer func() {
		err := reader.Close()
		if err != nil {
			t.Fatal(err)
		}
	}()
	it := reader.Iterator([]byte("a"))
	keys := make([][]byte, 0, len(data))
	key, _, valid := it.Current()
	for valid {
		keys = append(keys, key)
		it.Next()
		key, _, valid = it.Current()
	}

	if len(keys) != len(data) {
		t.Errorf("expected same number of keys, got %d != %d", len(keys), len(data))
	}
	for i, dk := range data {
		if !reflect.DeepEqual(dk.k, keys[i]) {
			t.Errorf("expected key %s got %s", dk.k, keys[i])
		}

	}

	err = it.Close()
	if err != nil {
		t.Fatal(err)
	}
}