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