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package cache
import (
"sync"
"github.com/ReneKroon/ttlcache"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
)
// statusCache is a wrapper around ttlcache.Cache to provide URL and URI lookups for gtsmodel.Status
type StatusCache struct {
cache *ttlcache.Cache // map of IDs -> cached statuses
urls map[string]string // map of status URLs -> IDs
uris map[string]string // map of status URIs -> IDs
mutex sync.Mutex
}
// newStatusCache returns a new instantiated statusCache object
func NewStatusCache() *StatusCache {
c := StatusCache{
cache: ttlcache.NewCache(),
urls: make(map[string]string, 100),
uris: make(map[string]string, 100),
mutex: sync.Mutex{},
}
// Set callback to purge lookup maps on expiration
c.cache.SetExpirationCallback(func(key string, value interface{}) {
status := value.(*gtsmodel.Status)
c.mutex.Lock()
delete(c.urls, status.URL)
delete(c.uris, status.URI)
c.mutex.Unlock()
})
return &c
}
// GetByID attempts to fetch a status from the cache by its ID
func (c *StatusCache) GetByID(id string) (*gtsmodel.Status, bool) {
c.mutex.Lock()
status, ok := c.getByID(id)
c.mutex.Unlock()
return status, ok
}
// GetByURL attempts to fetch a status from the cache by its URL
func (c *StatusCache) GetByURL(url string) (*gtsmodel.Status, bool) {
// Perform safe ID lookup
c.mutex.Lock()
id, ok := c.urls[url]
// Not found, unlock early
if !ok {
c.mutex.Unlock()
return nil, false
}
// Attempt status lookup
status, ok := c.getByID(id)
c.mutex.Unlock()
return status, ok
}
// GetByURI attempts to fetch a status from the cache by its URI
func (c *StatusCache) GetByURI(uri string) (*gtsmodel.Status, bool) {
// Perform safe ID lookup
c.mutex.Lock()
id, ok := c.uris[uri]
// Not found, unlock early
if !ok {
c.mutex.Unlock()
return nil, false
}
// Attempt status lookup
status, ok := c.getByID(id)
c.mutex.Unlock()
return status, ok
}
// getByID performs an unsafe (no mutex locks) lookup of status by ID
func (c *StatusCache) getByID(id string) (*gtsmodel.Status, bool) {
v, ok := c.cache.Get(id)
if !ok {
return nil, false
}
return v.(*gtsmodel.Status), true
}
// Put places a status in the cache
func (c *StatusCache) Put(status *gtsmodel.Status) {
if status == nil || status.ID == "" ||
status.URL == "" ||
status.URI == "" {
panic("invalid status")
}
c.mutex.Lock()
c.cache.Set(status.ID, status)
c.urls[status.URL] = status.ID
c.uris[status.URI] = status.ID
c.mutex.Unlock()
}
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