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package cache
import (
"errors"
"github.com/bradfitz/gomemcache/memcache"
"github.com/revel/revel"
"time"
)
// Wraps the Memcached client to meet the Cache interface.
type MemcachedCache struct {
*memcache.Client
defaultExpiration time.Duration
}
func NewMemcachedCache(hostList []string, defaultExpiration time.Duration) MemcachedCache {
return MemcachedCache{memcache.New(hostList...), defaultExpiration}
}
func (c MemcachedCache) Set(key string, value interface{}, expires time.Duration) error {
return c.invoke((*memcache.Client).Set, key, value, expires)
}
func (c MemcachedCache) Add(key string, value interface{}, expires time.Duration) error {
return c.invoke((*memcache.Client).Add, key, value, expires)
}
func (c MemcachedCache) Replace(key string, value interface{}, expires time.Duration) error {
return c.invoke((*memcache.Client).Replace, key, value, expires)
}
func (c MemcachedCache) Get(key string, ptrValue interface{}) error {
item, err := c.Client.Get(key)
if err != nil {
return convertMemcacheError(err)
}
return Deserialize(item.Value, ptrValue)
}
func (c MemcachedCache) GetMulti(keys ...string) (Getter, error) {
items, err := c.Client.GetMulti(keys)
if err != nil {
return nil, convertMemcacheError(err)
}
return ItemMapGetter(items), nil
}
func (c MemcachedCache) Delete(key string) error {
return convertMemcacheError(c.Client.Delete(key))
}
func (c MemcachedCache) Increment(key string, delta uint64) (newValue uint64, err error) {
newValue, err = c.Client.Increment(key, delta)
return newValue, convertMemcacheError(err)
}
func (c MemcachedCache) Decrement(key string, delta uint64) (newValue uint64, err error) {
newValue, err = c.Client.Decrement(key, delta)
return newValue, convertMemcacheError(err)
}
func (c MemcachedCache) Flush() error {
err := errors.New("revel/cache: can not flush memcached.")
revel.ERROR.Println(err)
return err
}
func (c MemcachedCache) invoke(f func(*memcache.Client, *memcache.Item) error,
key string, value interface{}, expires time.Duration) error {
switch expires {
case DEFAULT:
expires = c.defaultExpiration
case FOREVER:
expires = time.Duration(0)
}
b, err := Serialize(value)
if err != nil {
return err
}
return convertMemcacheError(f(c.Client, &memcache.Item{
Key: key,
Value: b,
Expiration: int32(expires / time.Second),
}))
}
// Implement a Getter on top of the returned item map.
type ItemMapGetter map[string]*memcache.Item
func (g ItemMapGetter) Get(key string, ptrValue interface{}) error {
item, ok := g[key]
if !ok {
return ErrCacheMiss
}
return Deserialize(item.Value, ptrValue)
}
func convertMemcacheError(err error) error {
switch err {
case nil:
return nil
case memcache.ErrCacheMiss:
return ErrCacheMiss
case memcache.ErrNotStored:
return ErrNotStored
}
revel.ERROR.Println("revel/cache:", err)
return err
}
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