Optimize library fetching mechanism

internal/torrent/refresh.go

@@ -20,6 +20,9 @@ func (t *TorrentManager) refreshTorrents(initialRun bool) {
 	instances, _, err := t.rd.GetTorrents(false)
 	if err != nil {
 		t.log.Warnf("Cannot get torrents: %v", err)
+		t.log.Info("Retrying in 5 seconds")
+		time.Sleep(5 * time.Second)
+		t.refreshTorrents(initialRun)
 		return
 	}
 

pkg/realdebrid/torrents.go

@@ -16,96 +16,64 @@ type fetchTorrentsResult struct {
 
 // GetTorrents returns all torrents, paginated
 func (rd *RealDebrid) GetTorrents(onlyOne bool) ([]Torrent, int, error) {
-	result := rd.fetchPageOfTorrents(1, 1)
-	if result.err != nil {
-		return nil, 0, result.err
-	}
-
-	totalElements := result.total
-
 	if onlyOne {
-		return result.torrents, totalElements, nil
+		result := rd.fetchPageOfTorrents(1, 1)
+		if result.err != nil {
+			return nil, 0, result.err
+		}
+		return result.torrents, result.total, nil
 	}
 
-	allTorrents := []Torrent{}
-	page := 1
-	pageSize := 500
+	pageSize := 250
 
-	maxPages := (totalElements + pageSize - 1) / pageSize
-	rd.log.Debugf("Torrents total count is %d", totalElements)
-	maxParallelThreads := 4
-	if maxPages < maxParallelThreads {
-		maxParallelThreads = maxPages
+	firstPage := rd.fetchPageOfTorrents(1, pageSize)
+	if firstPage.err != nil {
+		return nil, 0, firstPage.err
 	}
-	found := -1
-	for {
-		allResults := make(chan fetchTorrentsResult, maxParallelThreads) // Channel to collect results from goroutines
-		for i := 0; i < maxParallelThreads; i++ {                        // Launch GET_PARALLEL concurrent fetches
-			idx := i
-			rd.workerPool.Submit(func() {
-				if page+idx > maxPages {
-					allResults <- fetchTorrentsResult{
-						torrents: nil,
-						page:     page + idx,
-						total:    totalElements,
-						err:      nil,
-					}
-					return
-				}
-				allResults <- rd.fetchPageOfTorrents(page+idx, pageSize)
-			})
-		}
-		batches := make([][]Torrent, maxParallelThreads)
-		for i := 0; i < maxParallelThreads; i++ {
-			result := <-allResults
-			if result.err != nil {
-				rd.log.Warnf("Ignoring error when fetching torrents pg %d: %v", result.page, result.err)
-				return nil, 0, result.err
+
+	totalCount := firstPage.total
+	rd.log.Debugf("Torrents total count is %d", totalCount)
+
+	for cIdx, cached := range rd.torrentsCache { // N cached torrents
+		for fIdx, fresh := range firstPage.torrents { // 250 torrents in batch
+			cIdxEnd := len(rd.torrentsCache) - 1 - cIdx
+			fIdxEnd := totalCount - 1 - fIdx
+			if fresh.ID == cached.ID && fresh.Progress == cached.Progress && fIdxEnd == cIdxEnd {
+				allTorrents := firstPage.torrents[:fIdx]
+				allTorrents = append(allTorrents, rd.torrentsCache[cIdx:]...)
+				return allTorrents, len(allTorrents), nil
 			}
-			bIdx := (result.page - 1) % maxParallelThreads
-			batches[bIdx] = []Torrent{}
-			batches[bIdx] = append(batches[bIdx], result.torrents...)
-		}
-		for bIdx, batch := range batches { // 4 batches
-			if found < 0 && len(batch) > 0 {
-				cachedCount := len(rd.torrentsCache)
-				for cIdx, cached := range rd.torrentsCache { // N cached torrents
-					cIdxEnd := cachedCount - 1 - cIdx
-					for tIdx, torrent := range batch { // 250 torrents in batch
-						tIdxEnd := indexFromEnd(tIdx, page+bIdx, pageSize, totalElements)
-						if torrent.ID == cached.ID && torrent.Progress == cached.Progress && tIdxEnd == cIdxEnd {
-							found = ((page + bIdx - 1) * pageSize) + tIdx
-							break
-						}
-					}
-					if found >= 0 {
-						break
-					}
-				}
-			}
-			allTorrents = append(allTorrents, batch...)
-		}
-		if found >= 0 {
-			tIdx := found % pageSize
-			pageNum := (found / pageSize) + 1
-			tIdxEnd := indexFromEnd(tIdx, pageNum, pageSize, totalElements)
-			cIdx := len(rd.torrentsCache) - 1 - tIdxEnd
-			last := len(allTorrents) - 1
-			cIdx += last - found + 1
-			allTorrents = append(allTorrents, rd.torrentsCache[cIdx:]...)
 		}
+	}
 
-		rd.log.Debugf("Got %d/%d torrents", len(allTorrents), totalElements)
+	// Fetch all torrents in parallel
 
-		if len(allTorrents) >= totalElements || page >= maxPages {
-			break
+	maxPages := (totalCount + pageSize - 1) / pageSize
+	resultsCh := make(chan fetchTorrentsResult, maxPages)
+	for pageIdx := 2; pageIdx <= maxPages; pageIdx++ {
+		pageNum := pageIdx
+		rd.workerPool.Submit(func() {
+			resultsCh <- rd.fetchPageOfTorrents(pageNum, pageSize)
+		})
+	}
+	totalFetched := len(firstPage.torrents)
+	torrentPages := make([][]Torrent, maxPages)
+	for i := 2; i <= maxPages; i++ {
+		result := <-resultsCh
+		if result.err != nil {
+			return nil, 0, result.err
 		}
-
-		page += maxParallelThreads
+		torrentPages[result.page-1] = result.torrents
+		totalFetched += len(result.torrents)
+		rd.log.Debugf("Got %d/%d torrents", totalFetched, result.total)
+	}
+	allTorrents := firstPage.torrents
+	for _, page := range torrentPages {
+		allTorrents = append(allTorrents, page...)
 	}
 
 	rd.torrentsCache = allTorrents
-	return allTorrents, len(allTorrents), nil
+	return rd.torrentsCache, len(rd.torrentsCache), nil
 }
 
 func (rd *RealDebrid) fetchPageOfTorrents(page, limit int) fetchTorrentsResult {