Speed up opening database by deferring the initial refresh of total message count

app/Desktop/Common/NumberValueConverter.cs

@@ -5,7 +5,7 @@ using Avalonia.Data.Converters;
 namespace DHT.Desktop.Common {
 	sealed class NumberValueConverter : IValueConverter {
 		public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture) {
-			return string.Format(Program.Culture, "{0:n0}", value);
+			return value == null ? "-" : string.Format(Program.Culture, "{0:n0}", value);
 		}
 
 		public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture) {

app/Desktop/Main/Pages/ViewerPageModel.cs

@@ -35,7 +35,7 @@ namespace DHT.Desktop.Main.Pages {
 		private readonly IDatabaseFile db;
 
 		private bool isPageVisible = false;
-		
+
 		[Obsolete("Designer")]
 		public ViewerPageModel() : this(null!, DummyDatabaseFile.Instance) {}
 
@@ -46,7 +46,6 @@ namespace DHT.Desktop.Main.Pages {
 			FilterModel = new FilterPanelModel(window, db);
 			FilterModel.FilterPropertyChanged += OnFilterPropertyChanged;
 			db.Statistics.PropertyChanged += OnDbStatisticsChanged;
-			UpdateStatistics();
 		}
 
 		public void Dispose() {
@@ -73,13 +72,17 @@ namespace DHT.Desktop.Main.Pages {
 		}
 
 		private void UpdateStatistics() {
-			ExportedMessageText = "Will export " + db.CountMessages(FilterModel.CreateFilter()).Format() + " out of " + db.Statistics.TotalMessages.Format() + " message(s).";
+			var filter = FilterModel.CreateFilter();
+			var allMessagesCount = db.Statistics.TotalMessages?.Format() ?? "?";
+			var filteredMessagesCount = filter.IsEmpty ? allMessagesCount : db.CountMessages(filter).Format();
+
+			ExportedMessageText = "Will export " + filteredMessagesCount + " out of " + allMessagesCount + " message(s).";
 			OnPropertyChanged(nameof(ExportedMessageText));
 		}
 
 		private async Task<string> GenerateViewerContents() {
 			string json = ViewerJsonExport.Generate(db, FilterModel.CreateFilter());
-			
+
 			string index = await Resources.ReadTextAsync("Viewer/index.html");
 			string viewer = index.Replace("/*[JS]*/", await Resources.ReadJoinedAsync("Viewer/scripts/", '\n'))
 			                     .Replace("/*[CSS]*/", await Resources.ReadJoinedAsync("Viewer/styles/", '\n'))

app/Server/Data/Filters/MessageFilter.cs

@@ -3,11 +3,17 @@ using System.Collections.Generic;
 
 namespace DHT.Server.Data.Filters {
 	public sealed class MessageFilter {
-		public DateTime? StartDate { get; set; }
-		public DateTime? EndDate { get; set; }
+		public DateTime? StartDate { get; set; } = null;
+		public DateTime? EndDate { get; set; } = null;
 
 		public HashSet<ulong>? ChannelIds { get; set; } = null;
 		public HashSet<ulong>? UserIds { get; set; } = null;
 		public HashSet<ulong>? MessageIds { get; set; } = null;
+
+		public bool IsEmpty => StartDate == null &&
+		                       EndDate == null &&
+		                       ChannelIds == null &&
+		                       UserIds == null &&
+		                       MessageIds == null;
 	}
 }

app/Server/Database/DatabaseStatistics.cs

@@ -5,7 +5,7 @@ namespace DHT.Server.Database {
 		private long totalServers;
 		private long totalChannels;
 		private long totalUsers;
-		private long totalMessages;
+		private long? totalMessages;
 
 		public long TotalServers {
 			get => totalServers;
@@ -22,7 +22,7 @@ namespace DHT.Server.Database {
 			internal set => Change(ref totalUsers, value);
 		}
 
-		public long TotalMessages {
+		public long? TotalMessages {
 			get => totalMessages;
 			internal set => Change(ref totalMessages, value);
 		}

app/Server/Database/Sqlite/SqliteDatabaseFile.cs

@@ -46,11 +46,13 @@ namespace DHT.Server.Database.Sqlite {
 			this.Path = path;
 			this.Statistics = new DatabaseStatistics();
 
-			using var conn = pool.Take();
-			UpdateServerStatistics(conn);
-			UpdateChannelStatistics(conn);
-			UpdateUserStatistics(conn);
-			UpdateMessageStatistics(conn);
+			using (var conn = pool.Take()) {
+				UpdateServerStatistics(conn);
+				UpdateChannelStatistics(conn);
+				UpdateUserStatistics(conn);
+			}
+
+			messageStatisticsThread.RequestUpdate();
 		}
 
 		public void Dispose() {