multithread

util.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"slices"
 	"strings"
+	"sync"
 
 	"golang.org/x/net/proxy"
 )
@@ -135,28 +136,61 @@ func Download(manifest Manifest, downloadDir string, filen string) ([]byte, erro
 	// start downloading chunks
 	ret := make([]byte, manifest.Size)
 	totalMB := float32(manifest.Size) / 1024.0 / 1024.0
-	for _, fragment := range manifest.Fragments {
-		url := transformShaToURL(fragment.Sha512, fragment.Size)
-		content, err := getContent(url)
-		if err != nil {
-			return nil, err
-		}
-		downloaded += len(content) * len(fragment.Offsets)
-		for _, offset := range fragment.Offsets {
-			trackFrag = append(trackFrag, Frag{Offset: offset, Size: len(content)})
-			copy(ret[offset:offset+len(content)], content)
-		}
 
-		if Debug {
-			// save fragment to file in the fragments/ directory
-			if err := os.WriteFile(filepath.Join(downloadDir, "fragments", filen, fmt.Sprintf("%d.%s.%d.bytes", fragment.Offsets[0], fragment.Sha512, fragment.Size)), content, os.ModePerm); err != nil {
-				return nil, err
+	// A channel to signal the main goroutine to check for errors
+	doneChan := make(chan bool)
+
+	var wg sync.WaitGroup
+	wg.Add(DownThreads)
+	var mu sync.Mutex
+
+	fragChan := make(chan Fragment, DownThreads)
+	errChan := make(chan error, DownThreads)
+
+	// Start worker threads
+	for i := 0; i < DownThreads; i++ {
+		go func() {
+			defer wg.Done()
+			for fragment := range fragChan {
+				url := transformShaToURL(fragment.Sha512, fragment.Size)
+				content, err := getContent(url)
+				if err != nil {
+					errChan <- err
+					return
+				}
+				mu.Lock()
+				downloaded += len(content) * len(fragment.Offsets)
+				for _, offset := range fragment.Offsets {
+					trackFrag = append(trackFrag, Frag{Offset: offset, Size: len(content)})
+					copy(ret[offset:offset+len(content)], content)
+				}
+				percent := float32(downloaded) / float32(manifest.Size) * 100.0
+				downedMB := float32(downloaded) / 1024.0 / 1024.0
+				fmt.Printf("\r\033[32mDownloaded\033[0m %fMB/%fMB (\033[36m%.2f%%\033[0m) of \033[33m%s\033[0m", downedMB, totalMB, percent, filen)
+				mu.Unlock()
 			}
-		}
+		}()
+	}
 
-		percent := float32(downloaded) / float32(manifest.Size) * 100.0
-		downedMB := float32(downloaded) / 1024.0 / 1024.0
-		fmt.Printf("\r\033[32mDownloaded\033[0m %fMB/%fMB (\033[36m%.2f%%\033[0m) of \033[33m%s\033[0m", downedMB, totalMB, percent, filen)
+	// A separate goroutine to wait for all workers to finish and then close the error channel
+	go func() {
+		wg.Wait()
+		close(doneChan)
+	}()
+
+	// Send fragments to workers
+	for _, fragment := range manifest.Fragments {
+		fragChan <- fragment
+	}
+	close(fragChan)
+
+	// Wait for workers to finish or an error to occur
+	select {
+	case <-doneChan:
+		// All workers finished successfully
+	case err := <-errChan:
+		// An error occurred
+		return nil, err
 	}
 
 	// sort trackFrag by Offset