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scan.go
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scan.go
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package ledis
import (
"errors"
"regexp"
"github.com/ledisdb/ledisdb/store"
)
var errDataType = errors.New("error data type")
var errMetaKey = errors.New("error meta key")
//Scan scans the data. If inclusive is true, scan range [cursor, inf) else (cursor, inf)
func (db *DB) Scan(dataType DataType, cursor []byte, count int, inclusive bool, match string) ([][]byte, error) {
storeDataType, err := getDataStoreType(dataType)
if err != nil {
return nil, err
}
return db.scanGeneric(storeDataType, cursor, count, inclusive, match, false)
}
// RevScan scans the data reversed. if inclusive is true, revscan range (-inf, cursor] else (inf, cursor)
func (db *DB) RevScan(dataType DataType, cursor []byte, count int, inclusive bool, match string) ([][]byte, error) {
storeDataType, err := getDataStoreType(dataType)
if err != nil {
return nil, err
}
return db.scanGeneric(storeDataType, cursor, count, inclusive, match, true)
}
func getDataStoreType(dataType DataType) (byte, error) {
var storeDataType byte
switch dataType {
case KV:
storeDataType = KVType
case LIST:
storeDataType = LMetaType
case HASH:
storeDataType = HSizeType
case SET:
storeDataType = SSizeType
case ZSET:
storeDataType = ZSizeType
default:
return 0, errDataType
}
return storeDataType, nil
}
func buildMatchRegexp(match string) (*regexp.Regexp, error) {
var err error
var r *regexp.Regexp
if len(match) > 0 {
if r, err = regexp.Compile(match); err != nil {
return nil, err
}
}
return r, nil
}
func (db *DB) buildScanIterator(minKey []byte, maxKey []byte, inclusive bool, reverse bool) *store.RangeLimitIterator {
tp := store.RangeOpen
if !reverse {
if inclusive {
tp = store.RangeROpen
}
} else {
if inclusive {
tp = store.RangeLOpen
}
}
var it *store.RangeLimitIterator
if !reverse {
it = db.bucket.RangeIterator(minKey, maxKey, tp)
} else {
it = db.bucket.RevRangeIterator(minKey, maxKey, tp)
}
return it
}
func (db *DB) buildScanKeyRange(storeDataType byte, key []byte, reverse bool) (minKey []byte, maxKey []byte, err error) {
if !reverse {
if minKey, err = db.encodeScanMinKey(storeDataType, key); err != nil {
return
}
if maxKey, err = db.encodeScanMaxKey(storeDataType, nil); err != nil {
return
}
} else {
if minKey, err = db.encodeScanMinKey(storeDataType, nil); err != nil {
return
}
if maxKey, err = db.encodeScanMaxKey(storeDataType, key); err != nil {
return
}
}
return
}
func checkScanCount(count int) int {
if count <= 0 {
count = defaultScanCount
}
return count
}
func (db *DB) scanGeneric(storeDataType byte, key []byte, count int,
inclusive bool, match string, reverse bool) ([][]byte, error) {
r, err := buildMatchRegexp(match)
if err != nil {
return nil, err
}
minKey, maxKey, err := db.buildScanKeyRange(storeDataType, key, reverse)
if err != nil {
return nil, err
}
count = checkScanCount(count)
it := db.buildScanIterator(minKey, maxKey, inclusive, reverse)
v := make([][]byte, 0, count)
for i := 0; it.Valid() && i < count; it.Next() {
if k, err := db.decodeScanKey(storeDataType, it.Key()); err != nil {
continue
} else if r != nil && !r.Match(k) {
continue
} else {
v = append(v, k)
i++
}
}
it.Close()
return v, nil
}
func (db *DB) encodeScanMinKey(storeDataType byte, key []byte) ([]byte, error) {
return db.encodeScanKey(storeDataType, key)
}
func (db *DB) encodeScanMaxKey(storeDataType byte, key []byte) ([]byte, error) {
if len(key) > 0 {
return db.encodeScanKey(storeDataType, key)
}
k, err := db.encodeScanKey(storeDataType, nil)
if err != nil {
return nil, err
}
k[len(k)-1] = storeDataType + 1
return k, nil
}
func (db *DB) encodeScanKey(storeDataType byte, key []byte) ([]byte, error) {
switch storeDataType {
case KVType:
return db.encodeKVKey(key), nil
case LMetaType:
return db.lEncodeMetaKey(key), nil
case HSizeType:
return db.hEncodeSizeKey(key), nil
case ZSizeType:
return db.zEncodeSizeKey(key), nil
case SSizeType:
return db.sEncodeSizeKey(key), nil
default:
return nil, errDataType
}
}
func (db *DB) decodeScanKey(storeDataType byte, ek []byte) (key []byte, err error) {
switch storeDataType {
case KVType:
key, err = db.decodeKVKey(ek)
case LMetaType:
key, err = db.lDecodeMetaKey(ek)
case HSizeType:
key, err = db.hDecodeSizeKey(ek)
case ZSizeType:
key, err = db.zDecodeSizeKey(ek)
case SSizeType:
key, err = db.sDecodeSizeKey(ek)
default:
err = errDataType
}
return
}
// for special data scan
func (db *DB) buildDataScanKeyRange(storeDataType byte, key []byte, cursor []byte, reverse bool) (minKey []byte, maxKey []byte, err error) {
if !reverse {
if minKey, err = db.encodeDataScanMinKey(storeDataType, key, cursor); err != nil {
return
}
if maxKey, err = db.encodeDataScanMaxKey(storeDataType, key, nil); err != nil {
return
}
} else {
if minKey, err = db.encodeDataScanMinKey(storeDataType, key, nil); err != nil {
return
}
if maxKey, err = db.encodeDataScanMaxKey(storeDataType, key, cursor); err != nil {
return
}
}
return
}
func (db *DB) encodeDataScanMinKey(storeDataType byte, key []byte, cursor []byte) ([]byte, error) {
return db.encodeDataScanKey(storeDataType, key, cursor)
}
func (db *DB) encodeDataScanMaxKey(storeDataType byte, key []byte, cursor []byte) ([]byte, error) {
if len(cursor) > 0 {
return db.encodeDataScanKey(storeDataType, key, cursor)
}
k, err := db.encodeDataScanKey(storeDataType, key, nil)
if err != nil {
return nil, err
}
// here, the last byte is the start separator, set it to stop separator
k[len(k)-1] = k[len(k)-1] + 1
return k, nil
}
func (db *DB) encodeDataScanKey(storeDataType byte, key []byte, cursor []byte) ([]byte, error) {
switch storeDataType {
case HashType:
return db.hEncodeHashKey(key, cursor), nil
case ZSetType:
return db.zEncodeSetKey(key, cursor), nil
case SetType:
return db.sEncodeSetKey(key, cursor), nil
default:
return nil, errDataType
}
}
func (db *DB) buildDataScanIterator(storeDataType byte, key []byte, cursor []byte, count int,
inclusive bool, reverse bool) (*store.RangeLimitIterator, error) {
if err := checkKeySize(key); err != nil {
return nil, err
}
minKey, maxKey, err := db.buildDataScanKeyRange(storeDataType, key, cursor, reverse)
if err != nil {
return nil, err
}
it := db.buildScanIterator(minKey, maxKey, inclusive, reverse)
return it, nil
}
func (db *DB) hScanGeneric(key []byte, cursor []byte, count int, inclusive bool, match string, reverse bool) ([]FVPair, error) {
count = checkScanCount(count)
r, err := buildMatchRegexp(match)
if err != nil {
return nil, err
}
v := make([]FVPair, 0, count)
it, err := db.buildDataScanIterator(HashType, key, cursor, count, inclusive, reverse)
if err != nil {
return nil, err
}
defer it.Close()
for i := 0; it.Valid() && i < count; it.Next() {
_, f, err := db.hDecodeHashKey(it.Key())
if err != nil {
return nil, err
} else if r != nil && !r.Match(f) {
continue
}
v = append(v, FVPair{Field: f, Value: it.Value()})
i++
}
return v, nil
}
// HScan scans data for hash.
func (db *DB) HScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([]FVPair, error) {
return db.hScanGeneric(key, cursor, count, inclusive, match, false)
}
// HRevScan reversed scans data for hash.
func (db *DB) HRevScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([]FVPair, error) {
return db.hScanGeneric(key, cursor, count, inclusive, match, true)
}
func (db *DB) sScanGeneric(key []byte, cursor []byte, count int, inclusive bool, match string, reverse bool) ([][]byte, error) {
count = checkScanCount(count)
r, err := buildMatchRegexp(match)
if err != nil {
return nil, err
}
v := make([][]byte, 0, count)
it, err := db.buildDataScanIterator(SetType, key, cursor, count, inclusive, reverse)
if err != nil {
return nil, err
}
defer it.Close()
for i := 0; it.Valid() && i < count; it.Next() {
_, m, err := db.sDecodeSetKey(it.Key())
if err != nil {
return nil, err
} else if r != nil && !r.Match(m) {
continue
}
v = append(v, m)
i++
}
return v, nil
}
// SScan scans data for set.
func (db *DB) SScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([][]byte, error) {
return db.sScanGeneric(key, cursor, count, inclusive, match, false)
}
// SRevScan scans data reversed for set.
func (db *DB) SRevScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([][]byte, error) {
return db.sScanGeneric(key, cursor, count, inclusive, match, true)
}
func (db *DB) zScanGeneric(key []byte, cursor []byte, count int, inclusive bool, match string, reverse bool) ([]ScorePair, error) {
count = checkScanCount(count)
r, err := buildMatchRegexp(match)
if err != nil {
return nil, err
}
v := make([]ScorePair, 0, count)
it, err := db.buildDataScanIterator(ZSetType, key, cursor, count, inclusive, reverse)
if err != nil {
return nil, err
}
defer it.Close()
for i := 0; it.Valid() && i < count; it.Next() {
_, m, err := db.zDecodeSetKey(it.Key())
if err != nil {
return nil, err
} else if r != nil && !r.Match(m) {
continue
}
score, err := Int64(it.Value(), nil)
if err != nil {
return nil, err
}
v = append(v, ScorePair{Score: score, Member: m})
i++
}
return v, nil
}
// ZScan scans data for zset.
func (db *DB) ZScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([]ScorePair, error) {
return db.zScanGeneric(key, cursor, count, inclusive, match, false)
}
// ZRevScan scans data reversed for zset.
func (db *DB) ZRevScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([]ScorePair, error) {
return db.zScanGeneric(key, cursor, count, inclusive, match, true)
}