mirror of https://github.com/prometheus/prometheus
177 lines
3.6 KiB
Go
177 lines
3.6 KiB
Go
// Copyright 2013 Prometheus Team
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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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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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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 utility
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import (
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"container/list"
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"sync"
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)
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type Cache interface {
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Put(k, v interface{}) (replaced bool, err error)
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PutIfAbsent(k, v interface{}) (put bool, err error)
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Get(k interface{}) (v interface{}, ok bool, err error)
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Has(k interface{}) (ok bool, err error)
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Delete(k interface{}) (deleted bool, err error)
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Clear() (cleared bool, err error)
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}
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type LRUCache struct {
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list *list.List
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table map[interface{}]*list.Element
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limit uint
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size uint
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}
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func NewLRUCache(limit uint) *LRUCache {
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return &LRUCache{
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list: list.New(),
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table: map[interface{}]*list.Element{},
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limit: limit,
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}
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}
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func (c *LRUCache) Has(k interface{}) (has bool, err error) {
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_, ok := c.table[k]
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return ok, nil
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}
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func (c *LRUCache) Get(k interface{}) (v interface{}, ok bool, err error) {
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element, ok := c.table[k]
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if !ok {
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return nil, false, nil
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}
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c.moveToFront(element)
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return element.Value, true, nil
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}
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func (c *LRUCache) Put(k, v interface{}) (replaced bool, err error) {
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element, ok := c.table[k]
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if ok {
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c.updateInplace(element, v)
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return true, nil
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}
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c.addNew(k, v)
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return false, nil
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}
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func (c *LRUCache) PutIfAbsent(k, v interface{}) (put bool, err error) {
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if _, ok := c.table[k]; ok {
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return false, nil
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}
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c.addNew(k, v)
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return true, nil
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}
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func (c *LRUCache) Delete(k interface{}) (deleted bool, err error) {
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element, ok := c.table[k]
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if !ok {
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return false, nil
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}
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c.list.Remove(element)
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delete(c.table, k)
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return true, nil
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}
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func (c *LRUCache) Clear() (cleared bool, err error) {
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c.list.Init()
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c.table = map[interface{}]*list.Element{}
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c.size = 0
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return true, nil
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}
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func (c *LRUCache) updateInplace(e *list.Element, v interface{}) {
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e.Value = v
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c.moveToFront(e)
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c.checkCapacity()
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}
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func (c *LRUCache) moveToFront(e *list.Element) {
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c.list.MoveToFront(e)
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}
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func (c *LRUCache) addNew(k, v interface{}) {
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c.table[k] = c.list.PushFront(v)
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c.checkCapacity()
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}
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func (c *LRUCache) checkCapacity() {
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for c.size > c.limit {
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delElem := c.list.Back()
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v := delElem.Value
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c.list.Remove(delElem)
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delete(c.table, v)
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}
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}
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type SynchronizedCache struct {
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mu sync.Mutex
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c Cache
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}
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func (c *SynchronizedCache) Put(k, v interface{}) (replaced bool, err error) {
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c.mu.Lock()
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defer c.mu.Unlock()
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return c.c.Put(k, v)
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}
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func (c *SynchronizedCache) PutIfAbsent(k, v interface{}) (put bool, err error) {
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c.mu.Lock()
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defer c.mu.Unlock()
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return c.PutIfAbsent(k, v)
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}
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func (c *SynchronizedCache) Get(k interface{}) (v interface{}, ok bool, err error) {
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c.mu.Lock()
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defer c.mu.Unlock()
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return c.c.Get(k)
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}
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func (c *SynchronizedCache) Has(k interface{}) (ok bool, err error) {
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c.mu.Lock()
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defer c.mu.Unlock()
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return c.c.Has(k)
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}
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func (c *SynchronizedCache) Delete(k interface{}) (deleted bool, err error) {
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c.mu.Lock()
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defer c.mu.Unlock()
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return c.c.Delete(k)
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}
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func (c *SynchronizedCache) Clear() (cleared bool, err error) {
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c.mu.Lock()
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defer c.mu.Unlock()
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return c.c.Clear()
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}
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func NewSynchronizedCache(c Cache) *SynchronizedCache {
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return &SynchronizedCache{
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c: c,
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}
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}
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