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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 kv
import (
"context"
)
// UnionStore is a store that wraps a snapshot for read and a BufferStore for buffered write.
// Also, it provides some transaction related utilities.
type UnionStore interface {
MemBuffer
// GetKeyExistErrInfo gets the key exist error info for the lazy check.
GetKeyExistErrInfo(k Key) *existErrInfo
// DeleteKeyExistErrInfo deletes the key exist error info for the lazy check.
DeleteKeyExistErrInfo(k Key)
// ResetStmtKeyExistErrs deletes all the key exist error infos for the current statement.
ResetStmtKeyExistErrs()
// MergeStmtKeyExistErrs merges all the key exist error infos for the current statement.
MergeStmtKeyExistErrs()
// WalkBuffer iterates all buffered kv pairs.
WalkBuffer(f func(k Key, v []byte) error) error
// SetOption sets an option with a value, when val is nil, uses the default
// value of this option.
SetOption(opt Option, val interface{})
// DelOption deletes an option.
DelOption(opt Option)
// GetOption gets an option.
GetOption(opt Option) interface{}
// GetMemBuffer return the MemBuffer binding to this UnionStore.
GetMemBuffer() MemBuffer
}
// AssertionType is the type of a assertion.
type AssertionType int
// The AssertionType constants.
const (
None AssertionType = iota
Exist
NotExist
)
// Option is used for customizing kv store's behaviors during a transaction.
type Option int
// Options is an interface of a set of options. Each option is associated with a value.
type Options interface {
// Get gets an option value.
Get(opt Option) (v interface{}, ok bool)
}
type existErrInfo struct {
idxName string
value string
}
// NewExistErrInfo is used to new an existErrInfo
func NewExistErrInfo(idxName string, value string) *existErrInfo {
return &existErrInfo{idxName: idxName, value: value}
}
// GetIdxName gets the index name of the existed error.
func (e *existErrInfo) GetIdxName() string {
return e.idxName
}
// GetValue gets the existed value of the existed error.
func (e *existErrInfo) GetValue() string {
return e.value
}
// Err generates the error for existErrInfo
func (e *existErrInfo) Err() error {
return ErrKeyExists.FastGenByArgs(e.value, e.idxName)
}
// unionStore is an in-memory Store which contains a buffer for write and a
// snapshot for read.
type unionStore struct {
*BufferStore
keyExistErrs map[string]*existErrInfo // for the lazy check
stmtKeyExistErrs map[string]*existErrInfo
opts options
}
// NewUnionStore builds a new UnionStore.
func NewUnionStore(snapshot Snapshot) UnionStore {
return &unionStore{
BufferStore: NewBufferStore(snapshot),
keyExistErrs: make(map[string]*existErrInfo),
stmtKeyExistErrs: make(map[string]*existErrInfo),
opts: make(map[Option]interface{}),
}
}
// Get implements the Retriever interface.
func (us *unionStore) Get(ctx context.Context, k Key) ([]byte, error) {
v, err := us.MemBuffer.Get(ctx, k)
if IsErrNotFound(err) {
if _, ok := us.opts.Get(PresumeKeyNotExists); ok {
e, ok := us.opts.Get(PresumeKeyNotExistsError)
if ok {
us.stmtKeyExistErrs[string(k)] = e.(*existErrInfo)
if val, ok := us.opts.Get(CheckExists); ok {
checkExistMap := val.(map[string]struct{})
checkExistMap[string(k)] = struct{}{}
}
}
return nil, ErrNotExist
}
v, err = us.BufferStore.r.Get(ctx, k)
}
if err != nil {
return v, err
}
if len(v) == 0 {
return nil, ErrNotExist
}
return v, nil
}
func (us *unionStore) GetKeyExistErrInfo(k Key) *existErrInfo {
if c, ok := us.stmtKeyExistErrs[string(k)]; ok {
return c
}
if c, ok := us.keyExistErrs[string(k)]; ok {
return c
}
return nil
}
func (us *unionStore) DeleteKeyExistErrInfo(k Key) {
delete(us.stmtKeyExistErrs, string(k))
delete(us.keyExistErrs, string(k))
}
// SetOption implements the UnionStore SetOption interface.
func (us *unionStore) SetOption(opt Option, val interface{}) {
us.opts[opt] = val
}
// DelOption implements the UnionStore DelOption interface.
func (us *unionStore) DelOption(opt Option) {
delete(us.opts, opt)
}
// GetOption implements the UnionStore GetOption interface.
func (us *unionStore) GetOption(opt Option) interface{} {
return us.opts[opt]
}
// GetMemBuffer return the MemBuffer binding to this UnionStore.
func (us *unionStore) GetMemBuffer() MemBuffer {
return us.BufferStore.MemBuffer
}
func (us *unionStore) NewStagingBuffer() MemBuffer {
return us.BufferStore.NewStagingBuffer()
}
func (us *unionStore) Flush() (int, error) {
return us.BufferStore.Flush()
}
func (us *unionStore) Discard() {
us.BufferStore.Discard()
}
func (us *unionStore) ResetStmtKeyExistErrs() {
us.stmtKeyExistErrs = make(map[string]*existErrInfo)
}
func (us *unionStore) MergeStmtKeyExistErrs() {
for k, v := range us.stmtKeyExistErrs {
us.keyExistErrs[k] = v
}
us.stmtKeyExistErrs = make(map[string]*existErrInfo)
}
type options map[Option]interface{}
func (opts options) Get(opt Option) (interface{}, bool) {
v, ok := opts[opt]
return v, ok
}