reaper/reaper.go
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package reaper import ( "fmt" "sort" "sync" "time" "git.j3s.sh/vore/sqlite" "github.com/SlyMarbo/rss" ) type Reaper struct { // internal list of all rss feeds where the map // key represents the primary id of the key in the db feeds []rss.Feed // this mutex is used for locking writes to Feeds mu sync.Mutex db *sqlite.DB } func Summon(db *sqlite.DB) *Reaper { var feeds []rss.Feed reaper := Reaper{ feeds: feeds, mu: sync.Mutex{}, db: db, } return &reaper } func (r *Reaper) Start() { fmt.Println("reaper: starting") // Make initial url list urls := r.db.GetAllFeedURLs() for _, url := range urls { // Setting UpdateURL lets us defer fetching feed := rss.Feed{ UpdateURL: url, } r.feeds = append(r.feeds, feed) } for { r.updateAll() time.Sleep(15 * time.Minute) } } // Add the given rss feed to Reaper for maintenance. // If the given feed is already in reaper.Feeds, Add does nothing. func (r *Reaper) addFeed(f rss.Feed) { if !r.HasFeed(f.UpdateURL) { r.mu.Lock() r.feeds = append(r.feeds, f) r.mu.Unlock() } } // UpdateAll fetches every feed & attempts updating them // asynchronously, then prints the duration of the sync func (r *Reaper) updateAll() { start := time.Now() fmt.Printf("reaper: fetching %d feeds\n", len(r.feeds)) var wg sync.WaitGroup wg.Add(len(r.feeds)) for i := range r.feeds { go func(i int) { defer wg.Done() r.updateFeed(&r.feeds[i]) }(i) } go func() { wg.Wait() fmt.Printf("reaper: fetched %d feeds in %s\n", len(r.feeds), time.Since(start)) }() } // updateFeed triggers a fetch on the given feed, // and sets a fetch error in the db if there is one. func (r *Reaper) updateFeed(f *rss.Feed) { // return early if it's not time to refresh yet if !f.Refresh.After(time.Now()) { return } err := f.Update() if err != nil { fmt.Printf("[err] reaper: fetch failure url '%s' %s\n", f.UpdateURL, err) err = r.db.SetFeedFetchError(f.UpdateURL, err.Error()) } } // Have checks whether a given url is represented // in the reaper cache. func (r *Reaper) HasFeed(url string) bool { for i := range r.feeds { if r.feeds[i].UpdateURL == url { return true } } return false } // GetUserFeeds returns a list of feeds func (r *Reaper) GetUserFeeds(username string) []rss.Feed { urls := r.db.GetUserFeedURLs(username) var result []rss.Feed for i := range r.feeds { for _, url := range urls { if r.feeds[i].UpdateURL == url { result = append(result, r.feeds[i]) } } } r.SortFeeds(result) return result } func (r *Reaper) SortFeeds(f []rss.Feed) { sort.Slice(f, func(i, j int) bool { return f[i].Title < f[j].Title }) } func (r *Reaper) SortFeedItemsByDate(f []rss.Feed) []rss.Item { var posts []rss.Item for _, f := range f { for _, i := range f.Items { posts = append(posts, *i) } } sort.Slice(posts, func(i, j int) bool { return posts[i].Date.After(posts[j].Date) }) return posts } // FetchFeed attempts to fetch a feed from a given url, marshal // it into a feed object, and add it to Reaper. func (r *Reaper) Fetch(url string) error { feed, err := rss.Fetch(url) if err != nil { return err } r.addFeed(*feed) return nil }