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// Copyright 2013 Beego Authors
// Copyright 2014 The Macaron 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 (
"errors"
"sync"
"time"
)
// MemoryItem represents a memory cache item.
type MemoryItem struct {
val interface{}
created int64
expire int64
}
func (item *MemoryItem) hasExpired() bool {
return item.expire > 0 &&
(time.Now().Unix()-item.created) >= item.expire
}
// MemoryCacher represents a memory cache adapter implementation.
type MemoryCacher struct {
lock sync.RWMutex
items map[string]*MemoryItem
interval int // GC interval.
}
// NewMemoryCacher creates and returns a new memory cacher.
func NewMemoryCacher() *MemoryCacher {
return &MemoryCacher{items: make(map[string]*MemoryItem)}
}
// Put puts value into cache with key and expire time.
// If expired is 0, it will be deleted by next GC operation.
func (c *MemoryCacher) Put(key string, val interface{}, expire int64) error {
c.lock.Lock()
defer c.lock.Unlock()
c.items[key] = &MemoryItem{
val: val,
created: time.Now().Unix(),
expire: expire,
}
return nil
}
// Get gets cached value by given key.
func (c *MemoryCacher) Get(key string) interface{} {
c.lock.RLock()
defer c.lock.RUnlock()
item, ok := c.items[key]
if !ok {
return nil
}
if item.hasExpired() {
go c.Delete(key)
return nil
}
return item.val
}
// Delete deletes cached value by given key.
func (c *MemoryCacher) Delete(key string) error {
c.lock.Lock()
defer c.lock.Unlock()
delete(c.items, key)
return nil
}
// Incr increases cached int-type value by given key as a counter.
func (c *MemoryCacher) Incr(key string) (err error) {
c.lock.RLock()
defer c.lock.RUnlock()
item, ok := c.items[key]
if !ok {
return errors.New("key not exist")
}
item.val, err = Incr(item.val)
return err
}
// Decr decreases cached int-type value by given key as a counter.
func (c *MemoryCacher) Decr(key string) (err error) {
c.lock.RLock()
defer c.lock.RUnlock()
item, ok := c.items[key]
if !ok {
return errors.New("key not exist")
}
item.val, err = Decr(item.val)
return err
}
// IsExist returns true if cached value exists.
func (c *MemoryCacher) IsExist(key string) bool {
c.lock.RLock()
defer c.lock.RUnlock()
_, ok := c.items[key]
return ok
}
// Flush deletes all cached data.
func (c *MemoryCacher) Flush() error {
c.lock.Lock()
defer c.lock.Unlock()
c.items = make(map[string]*MemoryItem)
return nil
}
func (c *MemoryCacher) checkRawExpiration(key string) {
item, ok := c.items[key]
if !ok {
return
}
if item.hasExpired() {
delete(c.items, key)
}
}
func (c *MemoryCacher) checkExpiration(key string) {
c.lock.Lock()
defer c.lock.Unlock()
c.checkRawExpiration(key)
}
func (c *MemoryCacher) startGC() {
c.lock.Lock()
defer c.lock.Unlock()
if c.interval < 1 {
return
}
if c.items != nil {
for key, _ := range c.items {
c.checkRawExpiration(key)
}
}
time.AfterFunc(time.Duration(c.interval)*time.Second, func() { c.startGC() })
}
// StartAndGC starts GC routine based on config string settings.
func (c *MemoryCacher) StartAndGC(opt Options) error {
c.lock.Lock()
c.interval = opt.Interval
c.lock.Unlock()
go c.startGC()
return nil
}
func init() {
Register("memory", NewMemoryCacher())
}
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