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// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package structure
import (
"bytes"
"context"
"encoding/binary"
"strconv"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/kv"
)
// HashPair is the pair for (field, value) in a hash.
type HashPair struct {
Field []byte
Value []byte
}
type hashMeta struct {
FieldCount int64
}
func (meta hashMeta) Value() []byte {
buf := make([]byte, 8)
binary.BigEndian.PutUint64(buf[0:8], uint64(meta.FieldCount))
return buf
}
func (meta hashMeta) IsEmpty() bool {
return meta.FieldCount <= 0
}
// HSet sets the string value of a hash field.
func (t *TxStructure) HSet(key []byte, field []byte, value []byte) error {
if t.readWriter == nil {
return ErrWriteOnSnapshot
}
return t.updateHash(key, field, func([]byte) ([]byte, error) {
return value, nil
})
}
// HGet gets the value of a hash field.
func (t *TxStructure) HGet(key []byte, field []byte) ([]byte, error) {
dataKey := t.encodeHashDataKey(key, field)
value, err := t.reader.Get(context.TODO(), dataKey)
if kv.ErrNotExist.Equal(err) {
err = nil
}
return value, errors.Trace(err)
}
func (t *TxStructure) hashFieldIntegerVal(val int64) []byte {
return []byte(strconv.FormatInt(val, 10))
}
// EncodeHashAutoIDKeyValue returns the hash key-value generated by the key and the field
func (t *TxStructure) EncodeHashAutoIDKeyValue(key []byte, field []byte, val int64) (k, v []byte) {
return t.encodeHashDataKey(key, field), t.hashFieldIntegerVal(val)
}
// HInc increments the integer value of a hash field, by step, returns
// the value after the increment.
func (t *TxStructure) HInc(key []byte, field []byte, step int64) (int64, error) {
if t.readWriter == nil {
return 0, ErrWriteOnSnapshot
}
base := int64(0)
err := t.updateHash(key, field, func(oldValue []byte) ([]byte, error) {
if oldValue != nil {
var err error
base, err = strconv.ParseInt(string(oldValue), 10, 64)
if err != nil {
return nil, errors.Trace(err)
}
}
base += step
return t.hashFieldIntegerVal(base), nil
})
return base, errors.Trace(err)
}
// HGetInt64 gets int64 value of a hash field.
func (t *TxStructure) HGetInt64(key []byte, field []byte) (int64, error) {
value, err := t.HGet(key, field)
if err != nil || value == nil {
return 0, errors.Trace(err)
}
var n int64
n, err = strconv.ParseInt(string(value), 10, 64)
return n, errors.Trace(err)
}
func (t *TxStructure) updateHash(key []byte, field []byte, fn func(oldValue []byte) ([]byte, error)) error {
dataKey := t.encodeHashDataKey(key, field)
oldValue, err := t.loadHashValue(dataKey)
if err != nil {
return errors.Trace(err)
}
newValue, err := fn(oldValue)
if err != nil {
return errors.Trace(err)
}
// Check if new value is equal to old value.
if bytes.Equal(oldValue, newValue) {
return nil
}
if err = t.readWriter.Set(dataKey, newValue); err != nil {
return errors.Trace(err)
}
metaKey := t.encodeHashMetaKey(key)
meta, err := t.loadHashMeta(metaKey)
if err != nil {
return errors.Trace(err)
}
if oldValue == nil {
meta.FieldCount++
if err = t.readWriter.Set(metaKey, meta.Value()); err != nil {
return errors.Trace(err)
}
}
return nil
}
// HLen gets the number of fields in a hash.
func (t *TxStructure) HLen(key []byte) (int64, error) {
metaKey := t.encodeHashMetaKey(key)
meta, err := t.loadHashMeta(metaKey)
if err != nil {
return 0, errors.Trace(err)
}
return meta.FieldCount, nil
}
// HDel deletes one or more hash fields.
func (t *TxStructure) HDel(key []byte, fields ...[]byte) error {
if t.readWriter == nil {
return ErrWriteOnSnapshot
}
metaKey := t.encodeHashMetaKey(key)
meta, err := t.loadHashMeta(metaKey)
if err != nil || meta.IsEmpty() {
return errors.Trace(err)
}
var value []byte
for _, field := range fields {
dataKey := t.encodeHashDataKey(key, field)
value, err = t.loadHashValue(dataKey)
if err != nil {
return errors.Trace(err)
}
if value != nil {
if err = t.readWriter.Delete(dataKey); err != nil {
return errors.Trace(err)
}
meta.FieldCount--
}
}
if meta.IsEmpty() {
err = t.readWriter.Delete(metaKey)
} else {
err = t.readWriter.Set(metaKey, meta.Value())
}
return errors.Trace(err)
}
// HKeys gets all the fields in a hash.
func (t *TxStructure) HKeys(key []byte) ([][]byte, error) {
var keys [][]byte
err := t.iterateHash(key, func(field []byte, value []byte) error {
keys = append(keys, append([]byte{}, field...))
return nil
})
return keys, errors.Trace(err)
}
// HGetAll gets all the fields and values in a hash.
func (t *TxStructure) HGetAll(key []byte) ([]HashPair, error) {
var res []HashPair
err := t.iterateHash(key, func(field []byte, value []byte) error {
pair := HashPair{
Field: append([]byte{}, field...),
Value: append([]byte{}, value...),
}
res = append(res, pair)
return nil
})
return res, errors.Trace(err)
}
// HGetLastN gets latest N fields and values in hash.
func (t *TxStructure) HGetLastN(key []byte, num int) ([]HashPair, error) {
res := make([]HashPair, 0, num)
err := t.iterReverseHash(key, func(field []byte, value []byte) (bool, error) {
pair := HashPair{
Field: append([]byte{}, field...),
Value: append([]byte{}, value...),
}
res = append(res, pair)
if len(res) >= num {
return false, nil
}
return true, nil
})
return res, errors.Trace(err)
}
// HClear removes the hash value of the key.
func (t *TxStructure) HClear(key []byte) error {
metaKey := t.encodeHashMetaKey(key)
meta, err := t.loadHashMeta(metaKey)
if err != nil || meta.IsEmpty() {
return errors.Trace(err)
}
err = t.iterateHash(key, func(field []byte, value []byte) error {
k := t.encodeHashDataKey(key, field)
return errors.Trace(t.readWriter.Delete(k))
})
if err != nil {
return errors.Trace(err)
}
return errors.Trace(t.readWriter.Delete(metaKey))
}
func (t *TxStructure) iterateHash(key []byte, fn func(k []byte, v []byte) error) error {
dataPrefix := t.hashDataKeyPrefix(key)
it, err := t.reader.Iter(dataPrefix, dataPrefix.PrefixNext())
if err != nil {
return errors.Trace(err)
}
var field []byte
for it.Valid() {
if !it.Key().HasPrefix(dataPrefix) {
break
}
_, field, err = t.decodeHashDataKey(it.Key())
if err != nil {
return errors.Trace(err)
}
if err = fn(field, it.Value()); err != nil {
return errors.Trace(err)
}
err = it.Next()
if err != nil {
return errors.Trace(err)
}
}
return nil
}
// ReverseHashIterator is the reverse hash iterator.
type ReverseHashIterator struct {
t *TxStructure
iter kv.Iterator
prefix []byte
done bool
field []byte
}
// Next implements the Iterator Next.
func (i *ReverseHashIterator) Next() error {
err := i.iter.Next()
if err != nil {
return errors.Trace(err)
}
if !i.iter.Key().HasPrefix(i.prefix) {
i.done = true
return nil
}
_, field, err := i.t.decodeHashDataKey(i.iter.Key())
if err != nil {
return errors.Trace(err)
}
i.field = field
return nil
}
// Valid implements the Iterator Valid.
func (i *ReverseHashIterator) Valid() bool {
return i.iter.Valid() && !i.done
}
// Key implements the Iterator Key.
func (i *ReverseHashIterator) Key() []byte {
return i.field
}
// Value implements the Iterator Value.
func (i *ReverseHashIterator) Value() []byte {
return i.iter.Value()
}
// Close Implements the Iterator Close.
func (i *ReverseHashIterator) Close() {
}
// NewHashReverseIter creates a reverse hash iterator.
func NewHashReverseIter(t *TxStructure, key []byte) (*ReverseHashIterator, error) {
dataPrefix := t.hashDataKeyPrefix(key)
it, err := t.reader.IterReverse(dataPrefix.PrefixNext())
if err != nil {
return nil, errors.Trace(err)
}
return &ReverseHashIterator{
t: t,
iter: it,
prefix: dataPrefix,
}, nil
}
func (t *TxStructure) iterReverseHash(key []byte, fn func(k []byte, v []byte) (bool, error)) error {
dataPrefix := t.hashDataKeyPrefix(key)
it, err := t.reader.IterReverse(dataPrefix.PrefixNext())
if err != nil {
return errors.Trace(err)
}
var field []byte
for it.Valid() {
if !it.Key().HasPrefix(dataPrefix) {
break
}
_, field, err = t.decodeHashDataKey(it.Key())
if err != nil {
return errors.Trace(err)
}
more, err := fn(field, it.Value())
if !more || err != nil {
return errors.Trace(err)
}
err = it.Next()
if err != nil {
return errors.Trace(err)
}
}
return nil
}
func (t *TxStructure) loadHashMeta(metaKey []byte) (hashMeta, error) {
v, err := t.reader.Get(context.TODO(), metaKey)
if kv.ErrNotExist.Equal(err) {
err = nil
}
if err != nil {
return hashMeta{}, errors.Trace(err)
}
meta := hashMeta{FieldCount: 0}
if v == nil {
return meta, nil
}
if len(v) != 8 {
return meta, ErrInvalidListMetaData
}
meta.FieldCount = int64(binary.BigEndian.Uint64(v[0:8]))
return meta, nil
}
func (t *TxStructure) loadHashValue(dataKey []byte) ([]byte, error) {
v, err := t.reader.Get(context.TODO(), dataKey)
if kv.ErrNotExist.Equal(err) {
err = nil
v = nil
}
if err != nil {
return nil, errors.Trace(err)
}
return v, nil
}