githaven/vendor/github.com/pingcap/tidb/kv/union_store.go
Thomas Boerger b6a95a8cb3 Integrate public as bindata optionally (#293)
* 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
2016-11-30 00:26:36 +08:00

213 lines
5.1 KiB
Go

// 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 (
"bytes"
"github.com/juju/errors"
)
// 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
// CheckLazyConditionPairs loads all lazy values from store then checks if all values are matched.
// Lazy condition pairs should be checked before transaction commit.
CheckLazyConditionPairs() error
// 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)
}
// 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)
}
var (
p = newCache("memdb pool", 100, func() MemBuffer {
return NewMemDbBuffer()
})
)
// conditionPair is used to store lazy check condition.
// If condition not match (value is not equal as expected one), returns err.
type conditionPair struct {
key Key
value []byte
err error
}
// UnionStore is an in-memory Store which contains a buffer for write and a
// snapshot for read.
type unionStore struct {
*BufferStore
snapshot Snapshot // for read
lazyConditionPairs map[string](*conditionPair) // for delay check
opts options
}
// NewUnionStore builds a new UnionStore.
func NewUnionStore(snapshot Snapshot) UnionStore {
return &unionStore{
BufferStore: NewBufferStore(snapshot),
snapshot: snapshot,
lazyConditionPairs: make(map[string](*conditionPair)),
opts: make(map[Option]interface{}),
}
}
type lazyMemBuffer struct {
mb MemBuffer
}
func (lmb *lazyMemBuffer) Get(k Key) ([]byte, error) {
if lmb.mb == nil {
return nil, ErrNotExist
}
return lmb.mb.Get(k)
}
func (lmb *lazyMemBuffer) Set(key Key, value []byte) error {
if lmb.mb == nil {
lmb.mb = p.get()
}
return lmb.mb.Set(key, value)
}
func (lmb *lazyMemBuffer) Delete(k Key) error {
if lmb.mb == nil {
lmb.mb = p.get()
}
return lmb.mb.Delete(k)
}
func (lmb *lazyMemBuffer) Seek(k Key) (Iterator, error) {
if lmb.mb == nil {
lmb.mb = p.get()
}
return lmb.mb.Seek(k)
}
func (lmb *lazyMemBuffer) Release() {
if lmb.mb == nil {
return
}
lmb.mb.Release()
p.put(lmb.mb)
lmb.mb = nil
}
// Get implements the Retriever interface.
func (us *unionStore) Get(k Key) ([]byte, error) {
v, err := us.MemBuffer.Get(k)
if IsErrNotFound(err) {
if _, ok := us.opts.Get(PresumeKeyNotExists); ok {
e, ok := us.opts.Get(PresumeKeyNotExistsError)
if ok && e != nil {
us.markLazyConditionPair(k, nil, e.(error))
} else {
us.markLazyConditionPair(k, nil, ErrKeyExists)
}
return nil, errors.Trace(ErrNotExist)
}
}
if IsErrNotFound(err) {
v, err = us.BufferStore.r.Get(k)
}
if err != nil {
return v, errors.Trace(err)
}
if len(v) == 0 {
return nil, errors.Trace(ErrNotExist)
}
return v, nil
}
// markLazyConditionPair marks a kv pair for later check.
// If condition not match, should return e as error.
func (us *unionStore) markLazyConditionPair(k Key, v []byte, e error) {
us.lazyConditionPairs[string(k)] = &conditionPair{
key: k.Clone(),
value: v,
err: e,
}
}
// CheckLazyConditionPairs implements the UnionStore interface.
func (us *unionStore) CheckLazyConditionPairs() error {
if len(us.lazyConditionPairs) == 0 {
return nil
}
keys := make([]Key, 0, len(us.lazyConditionPairs))
for _, v := range us.lazyConditionPairs {
keys = append(keys, v.key)
}
values, err := us.snapshot.BatchGet(keys)
if err != nil {
return errors.Trace(err)
}
for k, v := range us.lazyConditionPairs {
if len(v.value) == 0 {
if _, exist := values[k]; exist {
return errors.Trace(v.err)
}
} else {
if bytes.Compare(values[k], v.value) != 0 {
return errors.Trace(ErrLazyConditionPairsNotMatch)
}
}
}
return nil
}
// 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)
}
// Release implements the UnionStore Release interface.
func (us *unionStore) Release() {
us.snapshot.Release()
us.BufferStore.Release()
}
type options map[Option]interface{}
func (opts options) Get(opt Option) (interface{}, bool) {
v, ok := opts[opt]
return v, ok
}