forked from tikv/pd
/
kv_base.go
84 lines (71 loc) · 1.94 KB
/
kv_base.go
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// Copyright 2017 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 core
import (
"sync"
"github.com/google/btree"
)
// KVBase is an abstract interface for load/save pd cluster data.
type KVBase interface {
Load(key string) (string, error)
LoadRange(key, endKey string, limit int) ([]string, error)
Save(key, value string) error
Delete(key string) error
}
type memoryKV struct {
sync.RWMutex
tree *btree.BTree
}
// NewMemoryKV returns an in-memory kvBase for testing.
func NewMemoryKV() KVBase {
return &memoryKV{
tree: btree.New(2),
}
}
type memoryKVItem struct {
key, value string
}
func (s memoryKVItem) Less(than btree.Item) bool {
return s.key < than.(memoryKVItem).key
}
func (kv *memoryKV) Load(key string) (string, error) {
kv.RLock()
defer kv.RUnlock()
item := kv.tree.Get(memoryKVItem{key, ""})
if item == nil {
return "", nil
}
return item.(memoryKVItem).value, nil
}
func (kv *memoryKV) LoadRange(key, endKey string, limit int) ([]string, error) {
kv.RLock()
defer kv.RUnlock()
res := make([]string, 0, limit)
kv.tree.AscendRange(memoryKVItem{key, ""}, memoryKVItem{endKey, ""}, func(item btree.Item) bool {
res = append(res, item.(memoryKVItem).value)
return len(res) < limit
})
return res, nil
}
func (kv *memoryKV) Save(key, value string) error {
kv.Lock()
defer kv.Unlock()
kv.tree.ReplaceOrInsert(memoryKVItem{key, value})
return nil
}
func (kv *memoryKV) Delete(key string) error {
kv.Lock()
defer kv.Unlock()
kv.tree.Delete(memoryKVItem{key, ""})
return nil
}