feat: improve error handling and introduce analysis cancellation support

- Added a new error type, ErrAnalysisCanceled, to handle user-initiated cancellations during audio analysis.
- Updated error handling in main.go and directory.go to utilize the new error type for clearer cancellation feedback.
- Enhanced synchronization in file.go to ensure safe access to processing errors across goroutines.

These changes enhance the robustness of audio processing by providing clearer error reporting and supporting graceful cancellation of analysis tasks.

internal/analysis/directory.go

@@ -3,6 +3,7 @@ package analysis
 import (
 	"context"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"log"
 	"math/rand"
@@ -383,9 +384,9 @@ func DirectoryAnalysis(settings *conf.Settings) error {
 		}
 
 		if analysisErr != nil {
-			if analysisErr == context.Canceled {
+			if errors.Is(analysisErr, context.Canceled) {
 				log.Printf("Analysis of file '%s' was interrupted", path)
-				return false, nil
+				return false, ErrAnalysisCanceled
 			}
 			return false, fmt.Errorf("error analyzing file '%s': %w", path, analysisErr)
 		}

internal/analysis/errors.go

@@ -0,0 +1,6 @@
+package analysis
+
+import "errors"
+
+// ErrAnalysisCanceled is returned when the analysis is canceled by the user
+var ErrAnalysisCanceled = errors.New("analysis canceled")

internal/analysis/file.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/tphakala/birdnet-go/internal/birdnet"
@@ -249,14 +250,18 @@ func processAudioFile(settings *conf.Settings, audioInfo *myaudio.AudioInfo, ctx
 
 	// Start result collector goroutine
 	var processingError error
+	var processingErrorMutex sync.Mutex
+
 	go func() {
 		if settings.Debug {
 			fmt.Println("DEBUG: Result collector started")
 		}
 		for i := 1; i <= totalChunks; i++ {
 			select {
 			case <-ctx.Done():
+				processingErrorMutex.Lock()
 				processingError = ctx.Err()
+				processingErrorMutex.Unlock()
 				close(doneChan)
 				return
 			case notes := <-resultChan:
@@ -269,14 +274,18 @@ func processAudioFile(settings *conf.Settings, audioInfo *myaudio.AudioInfo, ctx
 				if settings.Debug {
 					fmt.Printf("DEBUG: Collector received error: %v\n", err)
 				}
+				processingErrorMutex.Lock()
 				processingError = err
+				processingErrorMutex.Unlock()
 				close(doneChan)
 				return
 			case <-time.After(5 * time.Second):
 				if settings.Debug {
 					fmt.Printf("DEBUG: Timeout waiting for chunk %d results\n", i)
 				}
+				processingErrorMutex.Lock()
 				processingError = fmt.Errorf("timeout waiting for analysis results (processed %d/%d chunks)", chunkCount, totalChunks)
+				processingErrorMutex.Unlock()
 				close(doneChan)
 				return
 			}
@@ -305,7 +314,10 @@ func processAudioFile(settings *conf.Settings, audioInfo *myaudio.AudioInfo, ctx
 			filePosition = filePosition.Add(time.Duration((3.0 - bn.Settings.BirdNET.Overlap) * float64(time.Second)))
 			return nil
 		case <-doneChan:
-			return processingError
+			processingErrorMutex.Lock()
+			err := processingError
+			processingErrorMutex.Unlock()
+			return err
 		case <-time.After(5 * time.Second):
 			return fmt.Errorf("timeout sending chunk to processing")
 		}
@@ -328,11 +340,14 @@ func processAudioFile(settings *conf.Settings, audioInfo *myaudio.AudioInfo, ctx
 		return nil, fmt.Errorf("error processing audio: %w", err)
 	}
 
-	if processingError != nil {
+	processingErrorMutex.Lock()
+	err = processingError
+	processingErrorMutex.Unlock()
+	if err != nil {
 		if settings.Debug {
-			fmt.Printf("DEBUG: Processing error encountered: %v\n", processingError)
+			fmt.Printf("DEBUG: Processing error encountered: %v\n", err)
 		}
-		return allNotes, processingError
+		return allNotes, err
 	}
 
 	if settings.Debug {

main.go

@@ -2,13 +2,15 @@ package main
 
 import (
 	"embed"
+	"errors"
 	"fmt"
 	"os"
 	"runtime/pprof"
 	"time"
 
 	"github.com/spf13/viper"
 	"github.com/tphakala/birdnet-go/cmd"
+	"github.com/tphakala/birdnet-go/internal/analysis"
 	"github.com/tphakala/birdnet-go/internal/conf"
 	"github.com/tphakala/birdnet-go/internal/httpcontroller"
 )
@@ -68,7 +70,7 @@ func main() {
 	// Execute the root command
 	rootCmd := cmd.RootCommand(settings)
 	if err := rootCmd.Execute(); err != nil {
-		if err.Error() == "error processing audio: context canceled" {
+		if errors.Is(err, analysis.ErrAnalysisCanceled) {
 			// Clean exit for user-initiated cancellation
 			os.Exit(0)
 		}