forgejo-federation/vendor/github.com/pingcap/tidb/structure/hash.go

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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"
"encoding/binary"
"strconv"
"github.com/juju/errors"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/terror"
)
// 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 {
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.txn.Get(dataKey)
if terror.ErrorEqual(err, kv.ErrNotExist) {
err = nil
}
return value, errors.Trace(err)
}
// 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) {
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 []byte(strconv.FormatInt(base, 10)), 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.txn.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.txn.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 {
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.txn.Delete(dataKey); err != nil {
return errors.Trace(err)
}
meta.FieldCount--
}
}
if meta.IsEmpty() {
err = t.txn.Delete(metaKey)
} else {
err = t.txn.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)
}
// 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.txn.Delete(k))
})
if err != nil {
return errors.Trace(err)
}
return errors.Trace(t.txn.Delete(metaKey))
}
func (t *TxStructure) iterateHash(key []byte, fn func(k []byte, v []byte) error) error {
dataPrefix := t.hashDataKeyPrefix(key)
it, err := t.txn.Seek(dataPrefix)
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
}
func (t *TxStructure) loadHashMeta(metaKey []byte) (hashMeta, error) {
v, err := t.txn.Get(metaKey)
if terror.ErrorEqual(err, kv.ErrNotExist) {
err = nil
} else if err != nil {
return hashMeta{}, errors.Trace(err)
}
meta := hashMeta{FieldCount: 0}
if v == nil {
return meta, nil
}
if len(v) != 8 {
return meta, errors.New("invalid list meta data")
}
meta.FieldCount = int64(binary.BigEndian.Uint64(v[0:8]))
return meta, nil
}
func (t *TxStructure) loadHashValue(dataKey []byte) ([]byte, error) {
v, err := t.txn.Get(dataKey)
if terror.ErrorEqual(err, kv.ErrNotExist) {
err = nil
v = nil
} else if err != nil {
return nil, errors.Trace(err)
}
return v, nil
}