fixes race conditions

communities/codex_index_downloader.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"sync"
 
 	"go.uber.org/zap"
 )
@@ -15,6 +16,7 @@ type CodexIndexDownloader struct {
 	codexClient      CodexClientInterface
 	indexCid         string
 	filePath         string
+	mu               sync.RWMutex    // protects all fields below
 	datasetSize      int64           // stores the dataset size from the manifest
 	bytesCompleted   int64           // tracks download progress
 	downloadComplete bool            // true when file is fully downloaded and renamed
@@ -42,8 +44,10 @@ func (d *CodexIndexDownloader) GotManifest() <-chan struct{} {
 
 	go func() {
 		// Reset datasetSize to 0 to indicate no successful fetch yet
+		d.mu.Lock()
 		d.datasetSize = 0
 		d.downloadError = nil
+		d.mu.Unlock()
 
 		// Check for cancellation before starting
 		select {
@@ -68,7 +72,9 @@ func (d *CodexIndexDownloader) GotManifest() <-chan struct{} {
 		// Fetch manifest from Codex
 		manifest, err := d.codexClient.FetchManifestWithContext(ctx, d.indexCid)
 		if err != nil {
+			d.mu.Lock()
 			d.downloadError = err
+			d.mu.Unlock()
 			d.logger.Debug("failed to fetch manifest",
 				zap.String("indexCid", d.indexCid),
 				zap.Error(err))
@@ -79,7 +85,9 @@ func (d *CodexIndexDownloader) GotManifest() <-chan struct{} {
 
 		// Verify that the CID matches our configured indexCid
 		if manifest.CID != d.indexCid {
+			d.mu.Lock()
 			d.downloadError = fmt.Errorf("manifest CID mismatch: expected %s, got %s", d.indexCid, manifest.CID)
+			d.mu.Unlock()
 			d.logger.Debug("manifest CID mismatch",
 				zap.String("expected", d.indexCid),
 				zap.String("got", manifest.CID))
@@ -87,7 +95,9 @@ func (d *CodexIndexDownloader) GotManifest() <-chan struct{} {
 		}
 
 		// Store the dataset size for later use - this indicates success
+		d.mu.Lock()
 		d.datasetSize = manifest.Manifest.DatasetSize
+		d.mu.Unlock()
 
 		// Success! Close the channel to signal completion
 		close(ch)
@@ -98,15 +108,19 @@ func (d *CodexIndexDownloader) GotManifest() <-chan struct{} {
 
 // GetDatasetSize returns the dataset size from the last successfully fetched manifest
 func (d *CodexIndexDownloader) GetDatasetSize() int64 {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
 	return d.datasetSize
 }
 
 // DownloadIndexFile starts downloading the index file from Codex and writes it to the configured file path
 func (d *CodexIndexDownloader) DownloadIndexFile() {
 	// Reset progress counter and completion flag
+	d.mu.Lock()
 	d.bytesCompleted = 0
 	d.downloadComplete = false
 	d.downloadError = nil
+	d.mu.Unlock()
 
 	// Create cancellable context
 	ctx, cancel := context.WithCancel(context.Background())
@@ -129,7 +143,9 @@ func (d *CodexIndexDownloader) DownloadIndexFile() {
 		// This ensures atomic rename works (same filesystem)
 		tmpFile, err := os.CreateTemp(filepath.Dir(d.filePath), ".codex-download-*.tmp")
 		if err != nil {
+			d.mu.Lock()
 			d.downloadError = fmt.Errorf("failed to create temporary file: %w", err)
+			d.mu.Unlock()
 			d.logger.Debug("failed to create temporary file",
 				zap.String("filePath", d.filePath),
 				zap.Error(err))
@@ -146,12 +162,15 @@ func (d *CodexIndexDownloader) DownloadIndexFile() {
 		progressWriter := &progressWriter{
 			writer:    tmpFile,
 			completed: &d.bytesCompleted,
+			mu:        &d.mu,
 		}
 
 		// Use CodexClient to download and stream to temporary file with context for cancellation
 		err = d.codexClient.DownloadWithContext(ctx, d.indexCid, progressWriter)
 		if err != nil {
+			d.mu.Lock()
 			d.downloadError = fmt.Errorf("failed to download index file: %w", err)
+			d.mu.Unlock()
 			d.logger.Debug("failed to download index file",
 				zap.String("indexCid", d.indexCid),
 				zap.String("filePath", d.filePath),
@@ -162,7 +181,9 @@ func (d *CodexIndexDownloader) DownloadIndexFile() {
 
 		// Close the temporary file before renaming
 		if err := tmpFile.Close(); err != nil {
+			d.mu.Lock()
 			d.downloadError = fmt.Errorf("failed to close temporary file: %w", err)
+			d.mu.Unlock()
 			d.logger.Debug("failed to close temporary file",
 				zap.String("tmpPath", tmpPath),
 				zap.Error(err))
@@ -172,7 +193,9 @@ func (d *CodexIndexDownloader) DownloadIndexFile() {
 		// Atomically rename temporary file to final destination
 		// This ensures we only have a complete file at filePath
 		if err := os.Rename(tmpPath, d.filePath); err != nil {
+			d.mu.Lock()
 			d.downloadError = fmt.Errorf("failed to rename temporary file to final destination: %w", err)
+			d.mu.Unlock()
 			d.logger.Debug("failed to rename temporary file to final destination",
 				zap.String("tmpPath", tmpPath),
 				zap.String("filePath", d.filePath),
@@ -181,27 +204,37 @@ func (d *CodexIndexDownloader) DownloadIndexFile() {
 		}
 
 		// Mark download as complete only after successful rename
+		d.mu.Lock()
 		d.downloadComplete = true
+		d.mu.Unlock()
 	}()
 }
 
 // BytesCompleted returns the number of bytes downloaded so far
 func (d *CodexIndexDownloader) BytesCompleted() int64 {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
 	return d.bytesCompleted
 }
 
 // IsDownloadComplete returns true when the file has been fully downloaded and saved to disk
 func (d *CodexIndexDownloader) IsDownloadComplete() bool {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
 	return d.downloadComplete
 }
 
 // GetError returns the last error that occurred during manifest fetch or download, or nil if no error
 func (d *CodexIndexDownloader) GetError() error {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
 	return d.downloadError
 }
 
 // Length returns the total dataset size (equivalent to torrent file length)
 func (d *CodexIndexDownloader) Length() int64 {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
 	return d.datasetSize
 }
 
@@ -209,12 +242,15 @@ func (d *CodexIndexDownloader) Length() int64 {
 type progressWriter struct {
 	writer    io.Writer
 	completed *int64
+	mu        *sync.RWMutex
 }
 
 func (pw *progressWriter) Write(p []byte) (n int, err error) {
 	n, err = pw.writer.Write(p)
 	if n > 0 {
+		pw.mu.Lock()
 		*pw.completed += int64(n)
+		pw.mu.Unlock()
 	}
 	return n, err
 }