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|
package cache
import (
"sync"
"time"
"github.com/ydb-platform/ydb/library/go/yandex/tvm"
)
const (
Hit Status = iota
Miss
GonnaMissy
)
type (
Status int
Cache struct {
ttl time.Duration
maxTTL time.Duration
tickets map[tvm.ClientID]entry
aliases map[string]tvm.ClientID
lock sync.RWMutex
}
entry struct {
value *string
born time.Time
}
)
func New(ttl, maxTTL time.Duration) *Cache {
return &Cache{
ttl: ttl,
maxTTL: maxTTL,
tickets: make(map[tvm.ClientID]entry, 1),
aliases: make(map[string]tvm.ClientID, 1),
}
}
func (c *Cache) Gc() {
now := time.Now()
c.lock.Lock()
defer c.lock.Unlock()
for clientID, ticket := range c.tickets {
if ticket.born.Add(c.maxTTL).After(now) {
continue
}
delete(c.tickets, clientID)
for alias, aClientID := range c.aliases {
if clientID == aClientID {
delete(c.aliases, alias)
}
}
}
}
func (c *Cache) ClientIDs() []tvm.ClientID {
c.lock.RLock()
defer c.lock.RUnlock()
clientIDs := make([]tvm.ClientID, 0, len(c.tickets))
for clientID := range c.tickets {
clientIDs = append(clientIDs, clientID)
}
return clientIDs
}
func (c *Cache) Aliases() []string {
c.lock.RLock()
defer c.lock.RUnlock()
aliases := make([]string, 0, len(c.aliases))
for alias := range c.aliases {
aliases = append(aliases, alias)
}
return aliases
}
func (c *Cache) Load(clientID tvm.ClientID) (*string, Status) {
c.lock.RLock()
e, ok := c.tickets[clientID]
c.lock.RUnlock()
if !ok {
return nil, Miss
}
now := time.Now()
exp := e.born.Add(c.ttl)
if exp.After(now) {
return e.value, Hit
}
exp = e.born.Add(c.maxTTL)
if exp.After(now) {
return e.value, GonnaMissy
}
c.lock.Lock()
delete(c.tickets, clientID)
c.lock.Unlock()
return nil, Miss
}
func (c *Cache) LoadByAlias(alias string) (*string, Status) {
c.lock.RLock()
clientID, ok := c.aliases[alias]
c.lock.RUnlock()
if !ok {
return nil, Miss
}
return c.Load(clientID)
}
func (c *Cache) Store(clientID tvm.ClientID, alias string, value *string) {
c.lock.Lock()
defer c.lock.Unlock()
c.aliases[alias] = clientID
c.tickets[clientID] = entry{
value: value,
born: time.Now(),
}
}
|
