143 lines
3 KiB
Go
143 lines
3 KiB
Go
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// Copyright 2015 PingCAP, Inc.
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//
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// Copyright 2015 Wenbin Xiao
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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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"io"
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"github.com/juju/errors"
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"github.com/pingcap/tidb/kv/memkv"
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"github.com/pingcap/tidb/terror"
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"github.com/pingcap/tidb/util/types"
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)
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type btreeBuffer struct {
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tree *memkv.Tree
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}
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// NewBTreeBuffer returns a breeBuffer.
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func NewBTreeBuffer() MemBuffer {
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return &btreeBuffer{
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tree: memkv.NewTree(types.Collators[true]),
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}
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}
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// Get returns the value associated with the key; ErrNotExist error if the key does not exist.
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func (b *btreeBuffer) Get(k Key) ([]byte, error) {
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v, ok := b.tree.Get(toIfaces(k))
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if !ok {
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return nil, ErrNotExist
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}
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return fromIfaces(v), nil
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}
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// Set associates the key with the value.
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func (b *btreeBuffer) Set(k Key, v []byte) error {
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if len(v) == 0 {
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return errors.Trace(ErrCannotSetNilValue)
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}
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b.tree.Set(toIfaces(k), toIfaces(v))
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return nil
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}
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// Delete removes the entry from buffer with provided key.
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func (b *btreeBuffer) Delete(k Key) error {
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b.tree.Set(toIfaces(k), nil)
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return nil
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}
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// Release clear the whole buffer.
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func (b *btreeBuffer) Release() {
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b.tree.Clear()
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}
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type btreeIter struct {
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e *memkv.Enumerator
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k Key
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v []byte
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ok bool
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}
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// Seek creates a new Iterator based on the provided key.
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func (b *btreeBuffer) Seek(k Key) (Iterator, error) {
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var e *memkv.Enumerator
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var err error
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if k == nil {
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e, err = b.tree.SeekFirst()
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if err != nil {
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if terror.ErrorEqual(err, io.EOF) {
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return &btreeIter{ok: false}, nil
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}
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return &btreeIter{ok: false}, errors.Trace(err)
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}
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} else {
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key := toIfaces([]byte(k))
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e, _ = b.tree.Seek(key)
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}
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iter := &btreeIter{e: e}
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// the initial push...
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err = iter.Next()
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if err != nil {
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return &btreeIter{ok: false}, errors.Trace(err)
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}
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return iter, nil
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}
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// Close implements Iterator Close.
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func (i *btreeIter) Close() {
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//noop
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}
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// Key implements Iterator Key.
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func (i *btreeIter) Key() Key {
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return i.k
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}
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// Value implements Iterator Value.
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func (i *btreeIter) Value() []byte {
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return i.v
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}
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// Next implements Iterator Next.
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func (i *btreeIter) Next() error {
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k, v, err := i.e.Next()
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if err != nil {
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i.ok = false
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if terror.ErrorEqual(err, io.EOF) {
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return nil
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}
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return errors.Trace(err)
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}
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i.k, i.v, i.ok = fromIfaces(k), fromIfaces(v), true
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return nil
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}
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// Valid implements Iterator Valid.
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func (i *btreeIter) Valid() bool {
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return i.ok
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}
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func toIfaces(v []byte) []interface{} {
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return []interface{}{v}
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}
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func fromIfaces(v []interface{}) []byte {
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if v == nil {
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return nil
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}
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return v[0].([]byte)
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}
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