Add structured logging and better error handling

internal/jobs/download.go

@@ -4,7 +4,9 @@ import (
 	"context"
 	"errors"
 	"path/filepath"
+	"time"
 
+	"ddc/internal/explain"
 	"ddc/internal/extract"
 	"ddc/internal/fetch"
 )
@@ -17,6 +19,7 @@ func (manager *Manager) Pause(id string) error {
 	if !job.pause() {
 		return ErrJobBusy
 	}
+	job.logger().Info("pause requested")
 	return nil
 }
 
@@ -28,6 +31,7 @@ func (manager *Manager) Resume(id string) error {
 	if !job.begin(StatusQueued, StatusPaused, StatusFailed) {
 		return ErrJobBusy
 	}
+	job.logger().Info("download resumed", "has_saved_progress", job.currentDownloadState() != nil)
 	job.saveRecord()
 	manager.launchDownload(job)
 	return nil
@@ -44,17 +48,17 @@ func (manager *Manager) Reorder(id, direction string) error {
 	if job.currentStatus() != StatusQueued || !manager.slots.reorder(id, direction) {
 		return ErrJobBusy
 	}
+	job.logger().Debug("queue position changed", "direction", direction, "position", manager.slots.position(id))
 	return nil
 }
 
 func (manager *Manager) launchDownload(job *Job) {
 	runContext, cancelRun := job.startRun()
 	manager.slots.enqueue(job.id)
-	go func() {
-		defer job.workers.Done()
+	manager.runInBackground(job, "download", func() {
 		defer cancelRun(nil)
 		manager.download(job, runContext)
-	}()
+	})
 }
 
 func (manager *Manager) download(job *Job, runContext context.Context) {
@@ -65,18 +69,25 @@ func (manager *Manager) download(job *Job, runContext context.Context) {
 	defer manager.slots.release()
 
 	job.setStatus(StatusDownloading, "")
+	started := time.Now()
+	job.logger().Info("download started", "url", job.displayURL)
 	filePath, err := manager.downloader.Download(runContext, manager.fetchRequest(job))
 	if err != nil {
 		manager.handleDownloadError(job, runContext, err)
 		return
 	}
 	job.markDownloaded(filepath.Base(filePath))
+	job.logger().Info("download finished",
+		"file", filepath.Base(filePath),
+		"bytes", job.bytesDone.Load(),
+		"duration", time.Since(started).Round(time.Second).String(),
+	)
 
 	if job.autoExtract && extract.IsArchive(filePath) {
 		job.setStatus(StatusExtracting, "")
 		destination, err := manager.extractArchive(job, filePath)
 		if err != nil {
-			manager.finishWithError(job, StatusReady, "Extraction failed: ", err)
+			manager.failExtraction(job, err)
 			job.saveRecord()
 			return
 		}
@@ -98,6 +109,7 @@ func (manager *Manager) fetchRequest(job *Job) fetch.Request {
 		Connections:   current.ConnectionsPerDownload,
 		State:         job.currentDownloadState(),
 		Progress:      job,
+		Logger:        job.logger(),
 		Checkpoint: func(state fetch.State) {
 			job.setDownloadState(&state)
 			job.saveRecord()
@@ -109,14 +121,22 @@ func (manager *Manager) handleDownloadError(job *Job, runContext context.Context
 	switch {
 	case errors.Is(context.Cause(runContext), errPaused):
 		job.setStatus(StatusPaused, "")
+		job.logger().Info("download paused", "bytes_done", job.bytesDone.Load())
 	case job.jobContext.Err() != nil:
 		job.setStatus(StatusCancelled, "")
+		job.logger().Info("download stopped", "bytes_done", job.bytesDone.Load())
 		return
 	default:
 		if errors.Is(err, fetch.ErrSourceChanged) || errors.Is(err, fetch.ErrResumeUnsupported) {
 			job.setDownloadState(nil)
 		}
-		job.setStatus(StatusFailed, err.Error())
+		job.setStatus(StatusFailed, explain.Error(err))
+		job.logger().Error("download failed",
+			"url", job.displayURL,
+			"bytes_done", job.bytesDone.Load(),
+			"bytes_total", job.bytesTotal.Load(),
+			"error", err,
+		)
 	}
 	job.saveRecord()
 }