/
lru_counter.go
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/
lru_counter.go
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// Copyright 2013 Lars Buitinck
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
// Counter with eviction for least-recently used (LRU) items.
package lru
import (
"sync"
"time"
)
// a LRU counter that calls a function when an item is removed
type LRUCounter struct {
lru *LRU
sync.Mutex
}
// Create a new LRU cache for removalFunc with the desired capacity and ttl.
func NewLRUCounterTTL(removalFunc func(interface{}, int64), capacity int, ttl time.Duration) *LRUCounter {
r := func(key Key, value Value) {
vv := value.(int64)
removalFunc(key, vv)
}
l := New(nil, r, capacity, ttl)
return &LRUCounter{lru: l}
}
// Create a new LRU cache for removalFunc with the desired capacity.
func NewLRUCounter(removalFunc func(interface{}, int64), capacity int) *LRUCounter {
return NewLRUCounterTTL(removalFunc, capacity, 0)
}
// DisableTouchOnUpdate changes weather the timestamp used to compare TTL is updated when an element is updated
func (c *LRUCounter) DisableTouchOnUpdate() {
c.lru.DisableTouchOnUpdate()
}
// Fetch value for key in the cache, updating it's LRU position
func (c *LRUCounter) Get(key interface{}) (value int64, ok bool) {
v, ok := c.lru.Get(key)
if ok {
value = v.(int64)
}
return value, ok
}
// Number of items currently in the cache.
func (c *LRUCounter) Len() int {
return c.lru.Len()
}
func (c *LRUCounter) Capacity() int {
return c.lru.Capacity()
}
func (c *LRUCounter) Iter(keys chan Key, values chan Value) {
c.lru.Iter(keys, values)
}
// Flush all entries
func (c *LRUCounter) Flush() {
c.Lock()
c.lru.Flush()
c.Unlock()
}
// FlushExpired flushes entries that are expired based on the configured TTL
func (c *LRUCounter) FlushExpired() {
c.Lock()
c.lru.FlushExpired()
c.Unlock()
}
// Incr the key by value (goroutine safe)
func (c *LRUCounter) Incr(key interface{}, value int64) {
c.Lock()
if vv, ok := c.Get(key); ok {
value += vv
}
c.lru.Set(key, value)
c.Unlock()
}