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, you will receive a copy for thread-safety 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, you will receive a copy for thread-safety 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, you will receive a copy for thread-safety 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, returning a copy of status in cache func (c *StatusCache) getByID(id string) (*gtsmodel.Status, bool) { v, ok := c.cache.Get(id) if !ok { return nil, false } return copyStatus(v.(*gtsmodel.Status)), true } // Put places a status in the cache, ensuring that the object place is a copy for thread-safety func (c *StatusCache) Put(status *gtsmodel.Status) { if status == nil || status.ID == "" { panic("invalid status") } c.mutex.Lock() c.cache.Set(status.ID, copyStatus(status)) if status.URL != "" { c.urls[status.URL] = status.ID } if status.URI != "" { c.uris[status.URI] = status.ID } c.mutex.Unlock() } // copyStatus performs a surface-level copy of status, only keeping attached IDs intact, not the objects. // due to all the data being copied being 99% primitive types or strings (which are immutable and passed by ptr) // this should be a relatively cheap process func copyStatus(status *gtsmodel.Status) *gtsmodel.Status { return >smodel.Status{ ID: status.ID, URI: status.URI, URL: status.URL, Content: status.Content, AttachmentIDs: status.AttachmentIDs, Attachments: nil, TagIDs: status.TagIDs, Tags: nil, MentionIDs: status.MentionIDs, Mentions: nil, EmojiIDs: status.EmojiIDs, Emojis: nil, CreatedAt: status.CreatedAt, UpdatedAt: status.UpdatedAt, Local: status.Local, AccountID: status.AccountID, Account: nil, AccountURI: status.AccountURI, InReplyToID: status.InReplyToID, InReplyTo: nil, InReplyToURI: status.InReplyToURI, InReplyToAccountID: status.InReplyToAccountID, InReplyToAccount: nil, BoostOfID: status.BoostOfID, BoostOf: nil, BoostOfAccountID: status.BoostOfAccountID, BoostOfAccount: nil, ContentWarning: status.ContentWarning, Visibility: status.Visibility, Sensitive: status.Sensitive, Language: status.Language, CreatedWithApplicationID: status.CreatedWithApplicationID, VisibilityAdvanced: status.VisibilityAdvanced, ActivityStreamsType: status.ActivityStreamsType, Text: status.Text, Pinned: status.Pinned, } }