package favicons import ( "context" _ "embed" "errors" "fmt" "github.com/1f349/violet/database" "github.com/mrmelon54/rescheduler" "golang.org/x/sync/errgroup" "log" "sync" ) var ErrFaviconNotFound = errors.New("favicon not found") // Favicons is a dynamic favicon generator which supports overwriting favicons type Favicons struct { db *database.Queries cmd string cLock *sync.RWMutex faviconMap map[string]*FaviconList r *rescheduler.Rescheduler } // New creates a new dynamic favicon generator func New(db *database.Queries, inkscapeCmd string) *Favicons { f := &Favicons{ db: db, cmd: inkscapeCmd, cLock: &sync.RWMutex{}, faviconMap: make(map[string]*FaviconList), } f.r = rescheduler.NewRescheduler(f.threadCompile) // run compile to get the initial data f.Compile() return f } // GetIcons returns the favicon list for the provided host or nil if no // icon is found or generated func (f *Favicons) GetIcons(host string) *FaviconList { // read lock for safety f.cLock.RLock() defer f.cLock.RUnlock() // return value from map return f.faviconMap[host] } // Compile downloads the list of favicon mappings from the database and loads // them and the target favicons into memory for faster lookups // // This method makes use of the rescheduler instead of just ignoring multiple // calls. func (f *Favicons) Compile() { f.r.Run() } func (f *Favicons) threadCompile() { // new map favicons := make(map[string]*FaviconList) // compile map and check errors err := f.internalCompile(favicons) if err != nil { // log compile errors log.Printf("[Favicons] Compile failed: %s\n", err) return } // lock while replacing the map f.cLock.Lock() f.faviconMap = favicons f.cLock.Unlock() } // internalCompile is a hidden internal method for loading and generating all // favicons. func (f *Favicons) internalCompile(m map[string]*FaviconList) error { // query all rows in database rows, err := f.db.GetFavicons(context.Background()) if err != nil { return fmt.Errorf("failed to prepare rows: %w", err) } // loop over rows and scan in data using error group to catch errors var g errgroup.Group for _, row := range rows { // create favicon list for this row l := &FaviconList{ Ico: CreateFaviconImage(row.Ico), Png: CreateFaviconImage(row.Png), Svg: CreateFaviconImage(row.Svg), } // save the favicon list to the map m[row.Host] = l // run the pre-process in a separate goroutine g.Go(func() error { return l.PreProcess(f.convertSvgToPng) }) } return g.Wait() } // convertSvgToPng calls svg2png which runs inkscape in a subprocess func (f *Favicons) convertSvgToPng(in []byte) ([]byte, error) { return svg2png(f.cmd, in) }