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cache.go
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cache.go
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package gcache
import (
"errors"
"fmt"
"sync"
"time"
)
const (
TYPE_SIMPLE = "simple"
TYPE_LRU = "lru"
TYPE_LFU = "lfu"
TYPE_ARC = "arc"
)
type Cache interface {
Set(interface{}, interface{}) error
SetWithExpire(interface{}, interface{}, time.Duration) error
Get(interface{}) (interface{}, error)
GetIFPresent(interface{}) (interface{}, error)
GetALL() map[interface{}]interface{}
Remove(interface{}) error
Purge()
Keys() []interface{}
Len() int
Debug() map[string][]int
unsafeGet(interface{}, bool) (interface{}, error)
statsAccessor
}
type (
LoaderFunc func(interface{}) (interface{}, error)
LoaderExpireFunc func(interface{}) (interface{}, *time.Duration, error)
EvictedFunc func(interface{}, interface{})
PurgeVisitorFunc func(interface{}, interface{})
AddedFunc func(interface{}, interface{})
DeserializeFunc func(interface{}, interface{}) (interface{}, error)
SerializeFunc func(interface{}, interface{}) (interface{}, error)
)
type baseCache struct {
capacity int
size int
loaderExpireFunc LoaderExpireFunc
evictedFunc EvictedFunc
purgeVisitorFunc PurgeVisitorFunc
addedFunc AddedFunc
deserializeFunc DeserializeFunc
serializeFunc SerializeFunc
expiration *time.Duration
clock Clock
*stats
mu sync.RWMutex
loadGroup Group
}
type CacheBuilder struct {
tp string
capacity int
loaderExpireFunc LoaderExpireFunc
evictedFunc EvictedFunc
purgeVisitorFunc PurgeVisitorFunc
addedFunc AddedFunc
deserializeFunc DeserializeFunc
serializeFunc SerializeFunc
expiration *time.Duration
clock Clock
}
var KeyNotFoundError = errors.New("Key not found.")
func New(capacity int) *CacheBuilder {
return &CacheBuilder{
tp: TYPE_SIMPLE,
capacity: capacity,
clock: NewRealClock(),
}
}
// Set a loader function.
// loaderFunc: create a new value with this function if cached value is expired.
func (cb *CacheBuilder) LoaderFunc(loaderFunc LoaderFunc) *CacheBuilder {
cb.loaderExpireFunc = func(k interface{}) (interface{}, *time.Duration, error) {
v, err := loaderFunc(k)
return v, nil, err
}
return cb
}
func (cb *CacheBuilder) EvictType(tp string) *CacheBuilder {
cb.tp = tp
return cb
}
func (cb *CacheBuilder) Simple() *CacheBuilder {
return cb.EvictType(TYPE_SIMPLE)
}
func (cb *CacheBuilder) LRU() *CacheBuilder {
return cb.EvictType(TYPE_LRU)
}
func (cb *CacheBuilder) LFU() *CacheBuilder {
return cb.EvictType(TYPE_LFU)
}
func (cb *CacheBuilder) ARC() *CacheBuilder {
return cb.EvictType(TYPE_ARC)
}
// Set a loader function with expiration.
// loaderExpireFunc: create a new value with this function if cached value is expired.
// If nil returned instead of time.Duration from loaderExpireFunc than value will never expire.
func (cb *CacheBuilder) LoaderExpireFunc(loaderExpireFunc LoaderExpireFunc) *CacheBuilder {
cb.loaderExpireFunc = loaderExpireFunc
return cb
}
func (cb *CacheBuilder) EvictedFunc(evictedFunc EvictedFunc) *CacheBuilder {
cb.evictedFunc = evictedFunc
return cb
}
func (cb *CacheBuilder) PurgeVisitorFunc(purgeVisitorFunc PurgeVisitorFunc) *CacheBuilder {
cb.purgeVisitorFunc = purgeVisitorFunc
return cb
}
func (cb *CacheBuilder) AddedFunc(addedFunc AddedFunc) *CacheBuilder {
cb.addedFunc = addedFunc
return cb
}
func (cb *CacheBuilder) DeserializeFunc(deserializeFunc DeserializeFunc) *CacheBuilder {
cb.deserializeFunc = deserializeFunc
return cb
}
func (cb *CacheBuilder) SerializeFunc(serializeFunc SerializeFunc) *CacheBuilder {
cb.serializeFunc = serializeFunc
return cb
}
func (cb *CacheBuilder) Clock(clock Clock) *CacheBuilder {
cb.clock = clock
return cb
}
func (cb *CacheBuilder) Expiration(expiration time.Duration) *CacheBuilder {
cb.expiration = &expiration
return cb
}
func (cb *CacheBuilder) Build() (Cache, error) {
if cb.capacity <= 0 && cb.tp != TYPE_SIMPLE {
return nil, fmt.Errorf("gcache2: can't Build Cache, invalid Cache capacity (%v<=0)", cb.capacity)
}
return cb.build()
}
func (cb *CacheBuilder) build() (Cache, error) {
switch cb.tp {
case TYPE_SIMPLE:
return newSimpleCache(cb), nil
case TYPE_LRU:
return newLRUCache(cb), nil
case TYPE_LFU:
return newLFUCache(cb), nil
case TYPE_ARC:
return newARC(cb), nil
default:
return nil, fmt.Errorf("gcache2: can't build Cache, unknow Cache type (%s", cb.tp)
}
}
func buildCache(c *baseCache, cb *CacheBuilder) {
c.clock = cb.clock
c.capacity = cb.capacity
c.loaderExpireFunc = cb.loaderExpireFunc
c.expiration = cb.expiration
c.addedFunc = cb.addedFunc
c.deserializeFunc = cb.deserializeFunc
c.serializeFunc = cb.serializeFunc
c.evictedFunc = cb.evictedFunc
c.purgeVisitorFunc = cb.purgeVisitorFunc
c.stats = &stats{}
}
// load a new value using by specified key.
func (c *baseCache) load(key interface{}, cb func(interface{}, *time.Duration, error) (interface{}, error), isWait bool) (interface{}, bool, error) {
v, called, err := c.loadGroup.Do(key, func() (v interface{}, e error) {
defer func() {
if r := recover(); r != nil {
e = fmt.Errorf("Loader panics: %v", r)
}
}()
return cb(c.loaderExpireFunc(key))
}, isWait)
if err != nil {
return nil, called, err
}
return v, called, nil
}