mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-12-27 15:30:23 +00:00
84 lines
1.9 KiB
Go
84 lines
1.9 KiB
Go
/*
|
|
Copyright 2014 The Kubernetes Authors.
|
|
|
|
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,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
package cache
|
|
|
|
import (
|
|
"sync"
|
|
)
|
|
|
|
const (
|
|
shardsCount int = 32
|
|
)
|
|
|
|
type Cache []*cacheShard
|
|
|
|
func NewCache(maxSize int) Cache {
|
|
if maxSize < shardsCount {
|
|
maxSize = shardsCount
|
|
}
|
|
cache := make(Cache, shardsCount)
|
|
for i := 0; i < shardsCount; i++ {
|
|
cache[i] = &cacheShard{
|
|
items: make(map[uint64]interface{}),
|
|
maxSize: maxSize / shardsCount,
|
|
}
|
|
}
|
|
return cache
|
|
}
|
|
|
|
func (c Cache) getShard(index uint64) *cacheShard {
|
|
return c[index%uint64(shardsCount)]
|
|
}
|
|
|
|
// Returns true if object already existed, false otherwise.
|
|
func (c *Cache) Add(index uint64, obj interface{}) bool {
|
|
return c.getShard(index).add(index, obj)
|
|
}
|
|
|
|
func (c *Cache) Get(index uint64) (obj interface{}, found bool) {
|
|
return c.getShard(index).get(index)
|
|
}
|
|
|
|
type cacheShard struct {
|
|
items map[uint64]interface{}
|
|
sync.RWMutex
|
|
maxSize int
|
|
}
|
|
|
|
// Returns true if object already existed, false otherwise.
|
|
func (s *cacheShard) add(index uint64, obj interface{}) bool {
|
|
s.Lock()
|
|
defer s.Unlock()
|
|
_, isOverwrite := s.items[index]
|
|
if !isOverwrite && len(s.items) >= s.maxSize {
|
|
var randomKey uint64
|
|
for randomKey = range s.items {
|
|
break
|
|
}
|
|
delete(s.items, randomKey)
|
|
}
|
|
s.items[index] = obj
|
|
return isOverwrite
|
|
}
|
|
|
|
func (s *cacheShard) get(index uint64) (obj interface{}, found bool) {
|
|
s.RLock()
|
|
defer s.RUnlock()
|
|
obj, found = s.items[index]
|
|
return
|
|
}
|