gui, lib/scanner: Improve scan progress indication (ref #8331) (#9308)

gui/default/syncthing/core/syncthingController.js

@@ -1039,18 +1039,29 @@ angular.module('syncthing.core')
                 // Do the same thing in case we only have zero byte files to sync.
                 return 95;
             }
-            var pct = 100 * $scope.model[folder].inSyncBytes / $scope.model[folder].globalBytes;
+            return progressIntegerPercentage($scope.model[folder].inSyncBytes, $scope.model[folder].globalBytes);
-            return Math.floor(pct);
         };
 
         $scope.scanPercentage = function (folder) {
             if (!$scope.scanProgress[folder]) {
                 return undefined;
             }
-            var pct = 100 * $scope.scanProgress[folder].current / $scope.scanProgress[folder].total;
+            return progressIntegerPercentage($scope.scanProgress[folder].current, $scope.scanProgress[folder].total);
-            return Math.floor(pct);
         };
 
+        function progressIntegerPercentage(current, total) {
+            // Even after whatever is being tracked (e.g. hashed or synced
+            // bytes) is completed, there's likely some more work to be done to
+            // fully finish the process (db updates, ...). Users apparently
+            // don't like seeing 100%, so give them 99% to indicate "about to be
+            // finished".
+            if (current === total) {
+                return 99;
+            }
+            var pct = 100 * current / total;
+            return Math.floor(pct);
+        }
+
         $scope.scanRate = function (folder) {
             if (!$scope.scanProgress[folder]) {
                 return 0;

lib/scanner/walk.go

@@ -160,6 +160,11 @@ func (w *walker) walk(ctx context.Context) chan ScanResult {
 			total += file.Size
 		}
 
+		if len(filesToHash) == 0 {
+			close(finishedChan)
+			return
+		}
+
 		realToHashChan := make(chan protocol.FileInfo)
 		done := make(chan struct{})
 		progress := newByteCounter()
@@ -171,13 +176,7 @@ func (w *walker) walk(ctx context.Context) chan ScanResult {
 		go func() {
 			defer progress.Close()
 
-			for {
+			emitProgressEvent := func() {
-				select {
-				case <-done:
-					l.Debugln(w, "Walk progress done", w.Folder, w.Subs, w.Matcher)
-					ticker.Stop()
-					return
-				case <-ticker.C:
 				current := progress.Total()
 				rate := progress.Rate()
 				l.Debugf("%v: Walk %s %s current progress %d/%d at %.01f MiB/s (%d%%)", w, w.Folder, w.Subs, current, total, rate/1024/1024, current*100/total)
@@ -187,6 +186,17 @@ func (w *walker) walk(ctx context.Context) chan ScanResult {
 					"total":   total,
 					"rate":    rate, // bytes per second
 				})
+			}
+
+			for {
+				select {
+				case <-done:
+					emitProgressEvent()
+					l.Debugln(w, "Walk progress done", w.Folder, w.Subs, w.Matcher)
+					ticker.Stop()
+					return
+				case <-ticker.C:
+					emitProgressEvent()
 				case <-ctx.Done():
 					ticker.Stop()
 					return