gitroast/vendor/github.com/pingcap/tidb/kv/memkv/temp.go

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// Copyright 2013 The ql Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSES/QL-LICENSE file.
// 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 memkv
import (
"github.com/pingcap/tidb/util/types"
)
type btreeIterator interface {
Next() (k, v []interface{}, err error)
}
// Temp is the interface of a memory kv storage
type Temp interface {
Drop() (err error)
Get(k []interface{}) (v []interface{}, err error)
SeekFirst() (e btreeIterator, err error)
Set(k, v []interface{}) (err error)
}
// memtemp for join/groupby or any aggregation operation
type memTemp struct {
// memory btree
tree *Tree
}
// CreateTemp returns a new empty memory kv
func CreateTemp(asc bool) (_ Temp, err error) {
return &memTemp{
tree: NewTree(types.Collators[asc]),
}, nil
}
func (t *memTemp) Get(k []interface{}) (v []interface{}, err error) {
v, _ = t.tree.Get(k)
return
}
func (t *memTemp) Drop() (err error) { return }
func (t *memTemp) Set(k, v []interface{}) (err error) {
vv, err := types.Clone(v)
if err != nil {
return err
}
t.tree.Set(append([]interface{}(nil), k...), vv.([]interface{}))
return
}
func (t *memTemp) SeekFirst() (e btreeIterator, err error) {
it, err := t.tree.SeekFirst()
if err != nil {
return
}
return it, nil
}