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Reverse iterators (#224) 

with passing tests
This commit is contained in:
Jeremiah Andrews 2018-06-24 19:37:32 -07:00 committed by Jae Kwon
parent fb7ec62b29
commit cb08d28d40
6 changed files with 151 additions and 24 deletions
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2
Makefile
View File

@ -79,7 +79,7 @@ clean_certs:
rm -f db/remotedb/::.crt db/remotedb/::.key
test: gen_certs
go test -tags gcc $(shell go list ./... | grep -v vendor)
GOCACHE=off go test -tags gcc $(shell go list ./... | grep -v vendor)
make clean_certs
test100:

64
db/backend_test.go
View File

@ -149,3 +149,67 @@ func TestGoLevelDBBackend(t *testing.T) {
_, ok := db.(*GoLevelDB)
assert.True(t, ok)
}
func TestDBIterator(t *testing.T) {
for dbType := range backends {
t.Run(fmt.Sprintf("%v", dbType), func(t *testing.T) {
testDBIterator(t, dbType)
})
}
}
func testDBIterator(t *testing.T, backend DBBackendType) {
name := cmn.Fmt("test_%x", cmn.RandStr(12))
db := NewDB(name, backend, "")
defer cleanupDBDir("", name)
for i := 0; i < 10; i++ {
if i != 6 { // but skip 6.
db.Set(int642Bytes(int64(i)), nil)
}
}
verifyIterator(t, db.Iterator(nil, nil), []int64{0, 1, 2, 3, 4, 5, 7, 8, 9}, "forward iterator")
verifyIterator(t, db.ReverseIterator(nil, nil), []int64{9, 8, 7, 5, 4, 3, 2, 1, 0}, "reverse iterator")
verifyIterator(t, db.Iterator(nil, int642Bytes(0)), []int64(nil), "forward iterator to 0")
verifyIterator(t, db.ReverseIterator(nil, int642Bytes(10)), []int64(nil), "reverse iterator 10")
verifyIterator(t, db.Iterator(int642Bytes(0), nil), []int64{0, 1, 2, 3, 4, 5, 7, 8, 9}, "forward iterator from 0")
verifyIterator(t, db.Iterator(int642Bytes(1), nil), []int64{1, 2, 3, 4, 5, 7, 8, 9}, "forward iterator from 1")
verifyIterator(t, db.ReverseIterator(int642Bytes(10), nil), []int64{9, 8, 7, 5, 4, 3, 2, 1, 0}, "reverse iterator from 10")
verifyIterator(t, db.ReverseIterator(int642Bytes(9), nil), []int64{9, 8, 7, 5, 4, 3, 2, 1, 0}, "reverse iterator from 9")
verifyIterator(t, db.ReverseIterator(int642Bytes(8), nil), []int64{8, 7, 5, 4, 3, 2, 1, 0}, "reverse iterator from 8")
verifyIterator(t, db.Iterator(int642Bytes(5), int642Bytes(6)), []int64{5}, "forward iterator from 5 to 6")
verifyIterator(t, db.Iterator(int642Bytes(5), int642Bytes(7)), []int64{5}, "forward iterator from 5 to 7")
verifyIterator(t, db.Iterator(int642Bytes(5), int642Bytes(8)), []int64{5, 7}, "forward iterator from 5 to 8")
verifyIterator(t, db.Iterator(int642Bytes(6), int642Bytes(7)), []int64(nil), "forward iterator from 6 to 7")
verifyIterator(t, db.Iterator(int642Bytes(6), int642Bytes(8)), []int64{7}, "forward iterator from 6 to 8")
verifyIterator(t, db.Iterator(int642Bytes(7), int642Bytes(8)), []int64{7}, "forward iterator from 7 to 8")
verifyIterator(t, db.ReverseIterator(int642Bytes(5), int642Bytes(4)), []int64{5}, "reverse iterator from 5 to 4")
verifyIterator(t, db.ReverseIterator(int642Bytes(6), int642Bytes(4)), []int64{5}, "reverse iterator from 6 to 4")
verifyIterator(t, db.ReverseIterator(int642Bytes(7), int642Bytes(4)), []int64{7, 5}, "reverse iterator from 7 to 4")
verifyIterator(t, db.ReverseIterator(int642Bytes(6), int642Bytes(5)), []int64(nil), "reverse iterator from 6 to 5")
verifyIterator(t, db.ReverseIterator(int642Bytes(7), int642Bytes(5)), []int64{7}, "reverse iterator from 7 to 5")
verifyIterator(t, db.ReverseIterator(int642Bytes(7), int642Bytes(6)), []int64{7}, "reverse iterator from 7 to 6")
verifyIterator(t, db.Iterator(int642Bytes(0), int642Bytes(1)), []int64{0}, "forward iterator from 0 to 1")
verifyIterator(t, db.ReverseIterator(int642Bytes(9), int642Bytes(8)), []int64{9}, "reverse iterator from 9 to 8")
verifyIterator(t, db.Iterator(int642Bytes(2), int642Bytes(4)), []int64{2, 3}, "forward iterator from 2 to 4")
verifyIterator(t, db.Iterator(int642Bytes(4), int642Bytes(2)), []int64(nil), "forward iterator from 4 to 2")
verifyIterator(t, db.ReverseIterator(int642Bytes(4), int642Bytes(2)), []int64{4, 3}, "reverse iterator from 4 to 2")
verifyIterator(t, db.ReverseIterator(int642Bytes(2), int642Bytes(4)), []int64(nil), "reverse iterator from 2 to 4")
}
func verifyIterator(t *testing.T, itr Iterator, expected []int64, msg string) {
var list []int64
for itr.Valid() {
list = append(list, bytes2Int64(itr.Key()))
itr.Next()
}
assert.Equal(t, expected, list, msg)
}

45
db/c_level_db.go
View File

@ -190,7 +190,8 @@ func (db *CLevelDB) Iterator(start, end []byte) Iterator {
}
func (db *CLevelDB) ReverseIterator(start, end []byte) Iterator {
panic("not implemented yet") // XXX
itr := db.db.NewIterator(db.ro)
return newCLevelDBIterator(itr, start, end, true)
}
var _ Iterator = (*cLevelDBIterator)(nil)
@ -204,12 +205,25 @@ type cLevelDBIterator struct {
func newCLevelDBIterator(source *levigo.Iterator, start, end []byte, isReverse bool) *cLevelDBIterator {
if isReverse {
panic("not implemented yet") // XXX
}
if start != nil {
source.Seek(start)
if start == nil {
source.SeekToLast()
} else {
source.Seek(start)
if source.Valid() {
soakey := source.Key() // start or after key
if bytes.Compare(start, soakey) < 0 {
source.Prev()
}
} else {
source.SeekToLast()
}
}
} else {
source.SeekToFirst()
if start == nil {
source.SeekToFirst()
} else {
source.Seek(start)
}
}
return &cLevelDBIterator{
source: source,
@ -243,9 +257,16 @@ func (itr cLevelDBIterator) Valid() bool {
// If key is end or past it, invalid.
var end = itr.end
var key = itr.source.Key()
if end != nil && bytes.Compare(end, key) <= 0 {
itr.isInvalid = true
return false
if itr.isReverse {
if end != nil && bytes.Compare(key, end) <= 0 {
itr.isInvalid = true
return false
}
} else {
if end != nil && bytes.Compare(end, key) <= 0 {
itr.isInvalid = true
return false
}
}
// It's valid.
@ -267,7 +288,11 @@ func (itr cLevelDBIterator) Value() []byte {
func (itr cLevelDBIterator) Next() {
itr.assertNoError()
itr.assertIsValid()
itr.source.Next()
if itr.isReverse {
itr.source.Prev()
} else {
itr.source.Next()
}
}
func (itr cLevelDBIterator) Close() {

18
db/fsdb.go
View File

@ -151,21 +151,29 @@ func (db *FSDB) Mutex() *sync.Mutex {
}
func (db *FSDB) Iterator(start, end []byte) Iterator {
return db.MakeIterator(start, end, false)
}
func (db *FSDB) MakeIterator(start, end []byte, isReversed bool) Iterator {
db.mtx.Lock()
defer db.mtx.Unlock()
// We need a copy of all of the keys.
// Not the best, but probably not a bottleneck depending.
keys, err := list(db.dir, start, end)
keys, err := list(db.dir, start, end, isReversed)
if err != nil {
panic(errors.Wrapf(err, "Listing keys in %s", db.dir))
}
sort.Strings(keys)
if isReversed {
sort.Sort(sort.Reverse(sort.StringSlice(keys)))
} else {
sort.Strings(keys)
}
return newMemDBIterator(db, keys, start, end)
}
func (db *FSDB) ReverseIterator(start, end []byte) Iterator {
panic("not implemented yet") // XXX
return db.MakeIterator(start, end, true)
}
func (db *FSDB) nameToPath(name []byte) string {
@ -213,7 +221,7 @@ func remove(path string) error {
// List keys in a directory, stripping of escape sequences and dir portions.
// CONTRACT: returns os errors directly without wrapping.
func list(dirPath string, start, end []byte) ([]string, error) {
func list(dirPath string, start, end []byte, isReversed bool) ([]string, error) {
dir, err := os.Open(dirPath)
if err != nil {
return nil, err
@ -231,7 +239,7 @@ func list(dirPath string, start, end []byte) ([]string, error) {
return nil, fmt.Errorf("Failed to unescape %s while listing", name)
}
key := unescapeKey([]byte(n))
if IsKeyInDomain(key, start, end, false) {
if IsKeyInDomain(key, start, end, isReversed) {
keys = append(keys, string(key))
}
}

44
db/go_level_db.go
View File

@ -193,7 +193,8 @@ func (db *GoLevelDB) Iterator(start, end []byte) Iterator {
// Implements DB.
func (db *GoLevelDB) ReverseIterator(start, end []byte) Iterator {
panic("not implemented yet") // XXX
itr := db.db.NewIterator(nil, nil)
return newGoLevelDBIterator(itr, start, end, true)
}
type goLevelDBIterator struct {
@ -208,9 +209,26 @@ var _ Iterator = (*goLevelDBIterator)(nil)
func newGoLevelDBIterator(source iterator.Iterator, start, end []byte, isReverse bool) *goLevelDBIterator {
if isReverse {
panic("not implemented yet") // XXX
if start == nil {
source.Last()
} else {
valid := source.Seek(start)
if valid {
soakey := source.Key() // start or after key
if bytes.Compare(start, soakey) < 0 {
source.Prev()
}
} else {
source.Last()
}
}
} else {
if start == nil {
source.First()
} else {
source.Seek(start)
}
}
source.Seek(start)
return &goLevelDBIterator{
source: source,
start: start,
@ -245,9 +263,17 @@ func (itr *goLevelDBIterator) Valid() bool {
// If key is end or past it, invalid.
var end = itr.end
var key = itr.source.Key()
if end != nil && bytes.Compare(end, key) <= 0 {
itr.isInvalid = true
return false
if itr.isReverse {
if end != nil && bytes.Compare(key, end) <= 0 {
itr.isInvalid = true
return false
}
} else {
if end != nil && bytes.Compare(end, key) <= 0 {
itr.isInvalid = true
return false
}
}
// Valid
@ -276,7 +302,11 @@ func (itr *goLevelDBIterator) Value() []byte {
func (itr *goLevelDBIterator) Next() {
itr.assertNoError()
itr.assertIsValid()
itr.source.Next()
if itr.isReverse {
itr.source.Prev()
} else {
itr.source.Next()
}
}
// Implements Iterator.

2
db/remotedb/remotedb_test.go
View File

@ -38,7 +38,7 @@ func TestRemoteDB(t *testing.T) {
k1 := []byte("key-1")
v1 := client.Get(k1)
require.Equal(t, 0, len(v1), "expecting no key1 to have been stored")
require.Equal(t, 0, len(v1), "expecting no key1 to have been stored, got %X (%s)", v1, v1)
vv1 := []byte("value-1")
client.Set(k1, vv1)
gv1 := client.Get(k1)