mirror of
https://github.com/go-gitea/gitea.git
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* Dropped unused codekit config * Integrated dynamic and static bindata for public * Ignore public bindata * Add a general generate make task * Integrated flexible public assets into web command * Updated vendoring, added all missiong govendor deps * Made the linter happy with the bindata and dynamic code * Moved public bindata definition to modules directory * Ignoring the new bindata path now * Updated to the new public modules import path * Updated public bindata command and drop the new prefix
291 lines
7.6 KiB
Go
291 lines
7.6 KiB
Go
// Copyright 2015 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package kv
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import (
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"bytes"
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"encoding/binary"
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"io"
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"github.com/juju/errors"
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"github.com/pingcap/tidb/util/codec"
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"github.com/pingcap/tidb/util/types"
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)
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var (
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_ Index = (*kvIndex)(nil)
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_ IndexIterator = (*indexIter)(nil)
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)
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// IndexIterator is the interface for iterator of index data on KV store.
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type IndexIterator interface {
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Next() (k []types.Datum, h int64, err error)
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Close()
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}
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// Index is the interface for index data on KV store.
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type Index interface {
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// Create supports insert into statement.
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Create(rm RetrieverMutator, indexedValues []types.Datum, h int64) error
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// Delete supports delete from statement.
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Delete(m Mutator, indexedValues []types.Datum, h int64) error
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// Drop supports drop table, drop index statements.
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Drop(rm RetrieverMutator) error
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// Exist supports check index exists or not.
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Exist(rm RetrieverMutator, indexedValues []types.Datum, h int64) (bool, int64, error)
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// GenIndexKey generates an index key.
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GenIndexKey(indexedValues []types.Datum, h int64) (key []byte, distinct bool, err error)
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// Seek supports where clause.
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Seek(r Retriever, indexedValues []types.Datum) (iter IndexIterator, hit bool, err error)
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// SeekFirst supports aggregate min and ascend order by.
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SeekFirst(r Retriever) (iter IndexIterator, err error)
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}
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func encodeHandle(h int64) []byte {
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buf := &bytes.Buffer{}
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err := binary.Write(buf, binary.BigEndian, h)
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if err != nil {
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panic(err)
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}
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return buf.Bytes()
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}
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func decodeHandle(data []byte) (int64, error) {
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var h int64
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buf := bytes.NewBuffer(data)
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err := binary.Read(buf, binary.BigEndian, &h)
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return h, errors.Trace(err)
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}
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// indexIter is for KV store index iterator.
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type indexIter struct {
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it Iterator
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idx *kvIndex
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prefix Key
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}
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// Close does the clean up works when KV store index iterator is closed.
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func (c *indexIter) Close() {
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if c.it != nil {
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c.it.Close()
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c.it = nil
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}
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}
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// Next returns current key and moves iterator to the next step.
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func (c *indexIter) Next() (val []types.Datum, h int64, err error) {
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if !c.it.Valid() {
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return nil, 0, errors.Trace(io.EOF)
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}
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if !c.it.Key().HasPrefix(c.prefix) {
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return nil, 0, errors.Trace(io.EOF)
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}
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// get indexedValues
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buf := c.it.Key()[len(c.prefix):]
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vv, err := codec.Decode(buf)
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if err != nil {
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return nil, 0, errors.Trace(err)
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}
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// if index is *not* unique, the handle is in keybuf
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if !c.idx.unique {
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h = vv[len(vv)-1].GetInt64()
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val = vv[0 : len(vv)-1]
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} else {
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// otherwise handle is value
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h, err = decodeHandle(c.it.Value())
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if err != nil {
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return nil, 0, errors.Trace(err)
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}
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val = vv
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}
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// update new iter to next
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err = c.it.Next()
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if err != nil {
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return nil, 0, errors.Trace(err)
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}
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return
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}
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// kvIndex is the data structure for index data in the KV store.
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type kvIndex struct {
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indexName string
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indexID int64
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unique bool
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prefix Key
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}
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// GenIndexPrefix generates the index prefix.
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func GenIndexPrefix(indexPrefix Key, indexID int64) Key {
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buf := make([]byte, 0, len(indexPrefix)+8)
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buf = append(buf, indexPrefix...)
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buf = codec.EncodeInt(buf, indexID)
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return buf
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}
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// NewKVIndex builds a new kvIndex object.
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func NewKVIndex(indexPrefix Key, indexName string, indexID int64, unique bool) Index {
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index := &kvIndex{
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indexName: indexName,
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indexID: indexID,
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unique: unique,
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prefix: GenIndexPrefix(indexPrefix, indexID),
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}
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return index
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}
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// GenIndexKey generates storage key for index values. Returned distinct indicates whether the
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// indexed values should be distinct in storage (i.e. whether handle is encoded in the key).
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func (c *kvIndex) GenIndexKey(indexedValues []types.Datum, h int64) (key []byte, distinct bool, err error) {
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if c.unique {
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// See: https://dev.mysql.com/doc/refman/5.7/en/create-index.html
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// A UNIQUE index creates a constraint such that all values in the index must be distinct.
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// An error occurs if you try to add a new row with a key value that matches an existing row.
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// For all engines, a UNIQUE index permits multiple NULL values for columns that can contain NULL.
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distinct = true
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for _, cv := range indexedValues {
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if cv.Kind() == types.KindNull {
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distinct = false
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break
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}
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}
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}
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key = append(key, c.prefix...)
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if distinct {
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key, err = codec.EncodeKey(key, indexedValues...)
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} else {
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key, err = codec.EncodeKey(key, append(indexedValues, types.NewDatum(h))...)
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}
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if err != nil {
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return nil, false, errors.Trace(err)
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}
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return
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}
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// Create creates a new entry in the kvIndex data.
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// If the index is unique and there is an existing entry with the same key, Create will return ErrKeyExists.
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func (c *kvIndex) Create(rm RetrieverMutator, indexedValues []types.Datum, h int64) error {
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key, distinct, err := c.GenIndexKey(indexedValues, h)
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if err != nil {
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return errors.Trace(err)
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}
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if !distinct {
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// TODO: reconsider value
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err = rm.Set(key, []byte("timestamp?"))
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return errors.Trace(err)
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}
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_, err = rm.Get(key)
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if IsErrNotFound(err) {
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err = rm.Set(key, encodeHandle(h))
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return errors.Trace(err)
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}
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return errors.Trace(ErrKeyExists)
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}
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// Delete removes the entry for handle h and indexdValues from KV index.
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func (c *kvIndex) Delete(m Mutator, indexedValues []types.Datum, h int64) error {
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key, _, err := c.GenIndexKey(indexedValues, h)
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if err != nil {
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return errors.Trace(err)
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}
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err = m.Delete(key)
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return errors.Trace(err)
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}
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// Drop removes the KV index from store.
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func (c *kvIndex) Drop(rm RetrieverMutator) error {
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it, err := rm.Seek(c.prefix)
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if err != nil {
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return errors.Trace(err)
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}
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defer it.Close()
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// remove all indices
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for it.Valid() {
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if !it.Key().HasPrefix(c.prefix) {
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break
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}
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err := rm.Delete(it.Key())
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if err != nil {
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return errors.Trace(err)
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}
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err = it.Next()
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if err != nil {
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return errors.Trace(err)
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}
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}
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return nil
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}
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// Seek searches KV index for the entry with indexedValues.
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func (c *kvIndex) Seek(r Retriever, indexedValues []types.Datum) (iter IndexIterator, hit bool, err error) {
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key, _, err := c.GenIndexKey(indexedValues, 0)
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if err != nil {
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return nil, false, errors.Trace(err)
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}
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it, err := r.Seek(key)
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if err != nil {
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return nil, false, errors.Trace(err)
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}
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// check if hit
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hit = false
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if it.Valid() && it.Key().Cmp(key) == 0 {
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hit = true
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}
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return &indexIter{it: it, idx: c, prefix: c.prefix}, hit, nil
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}
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// SeekFirst returns an iterator which points to the first entry of the KV index.
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func (c *kvIndex) SeekFirst(r Retriever) (iter IndexIterator, err error) {
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it, err := r.Seek(c.prefix)
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if err != nil {
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return nil, errors.Trace(err)
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}
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return &indexIter{it: it, idx: c, prefix: c.prefix}, nil
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}
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func (c *kvIndex) Exist(rm RetrieverMutator, indexedValues []types.Datum, h int64) (bool, int64, error) {
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key, distinct, err := c.GenIndexKey(indexedValues, h)
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if err != nil {
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return false, 0, errors.Trace(err)
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}
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value, err := rm.Get(key)
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if IsErrNotFound(err) {
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return false, 0, nil
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}
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if err != nil {
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return false, 0, errors.Trace(err)
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}
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// For distinct index, the value of key is handle.
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if distinct {
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handle, err := decodeHandle(value)
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if err != nil {
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return false, 0, errors.Trace(err)
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}
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if handle != h {
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return true, handle, errors.Trace(ErrKeyExists)
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}
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return true, handle, nil
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}
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return true, h, nil
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}
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