UDC: use system time only on startup and then work with timespans relative to that. This ensures we don't collect confusing data if the system time changes while SharpDevelop is running.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@5926 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/AddIns/Misc/UsageDataCollector/UsageDataCollector/UsageDataSessionWriter.cs

@@ -35,6 +35,8 @@ namespace ICSharpCode.UsageDataCollector
 		SQLiteConnection connection;
 		long sessionID;
 		Timer timer;
+		DateTime startTime;
+		Stopwatch stopwatch;
 		
 		/// <summary>
 		/// Opens/Creates the database and starts writing a new session to it.
@@ -172,10 +174,13 @@ namespace ICSharpCode.UsageDataCollector
 		
 		void StartSession()
 		{
+			startTime = DateTime.UtcNow;
+			stopwatch = Stopwatch.StartNew();
 			using (SQLiteTransaction transaction = this.connection.BeginTransaction()) {
 				using (SQLiteCommand cmd = this.connection.CreateCommand()) {
-					cmd.CommandText = "INSERT INTO Sessions (startTime) VALUES (datetime('now'));" +
+					cmd.CommandText = "INSERT INTO Sessions (startTime) VALUES (?);" +
 						"SELECT last_insert_rowid();";
+					cmd.Parameters.Add(new SQLiteParameter { Value = TimeToString(startTime) });
 					sessionID = (long)cmd.ExecuteScalar();
 				}
 				AddEnvironmentData(GetDefaultEnvironmentData());
@@ -183,12 +188,18 @@ namespace ICSharpCode.UsageDataCollector
 			}
 		}
 		
+		DateTime GetNow()
+		{
+			return startTime + stopwatch.Elapsed;
+		}
+		
 		void EndSession()
 		{
 			using (SQLiteTransaction transaction = this.connection.BeginTransaction()) {
 				FlushOutstandingChanges();
 				using (SQLiteCommand cmd = this.connection.CreateCommand()) {
-					cmd.CommandText = "UPDATE Sessions SET endTime = datetime('now') WHERE id = ?;";
+					cmd.CommandText = "UPDATE Sessions SET endTime = ? WHERE id = ?;";
+					cmd.Parameters.Add(new SQLiteParameter { Value = TimeToString(GetNow()) });
 					cmd.Parameters.Add(new SQLiteParameter { Value = sessionID });
 					cmd.ExecuteNonQuery();
 				}
@@ -239,7 +250,7 @@ namespace ICSharpCode.UsageDataCollector
 			lock (lockObj) {
 				if (isDisposed)
 					throw new ObjectDisposedException(GetType().Name);
-				FeatureUse featureUse = new FeatureUse(this);
+				FeatureUse featureUse = new FeatureUse(this, GetNow());
 				featureUse.name = featureName;
 				featureUse.activation = activationMethod;
 				delayedStart.Enqueue(featureUse);
@@ -252,11 +263,16 @@ namespace ICSharpCode.UsageDataCollector
 			lock (lockObj) {
 				if (isDisposed)
 					return;
-				featureUse.endTime = DateTime.UtcNow;
+				featureUse.endTime = GetNow();
 				delayedEnd.Enqueue(featureUse);
 			}
 		}
 		
+		static string TimeToString(DateTime time)
+		{
+			return time.ToString("yyyy-MM-dd hh:mm:ss", CultureInfo.InvariantCulture);
+		}
+		
 		void FlushOutstandingChanges()
 		{
 			//Console.WriteLine("Flushing {0} starts and {1} ends", delayedStart.Count, delayedEnd.Count);
@@ -275,7 +291,7 @@ namespace ICSharpCode.UsageDataCollector
 						cmd.Parameters.Add(activationMethod = new SQLiteParameter());
 						while (delayedStart.Count > 0) {
 							FeatureUse use = delayedStart.Dequeue();
-							time.Value = use.startTime.ToString("yyyy-MM-dd hh:mm:ss", CultureInfo.InvariantCulture);
+							time.Value = TimeToString(use.startTime);
 							feature.Value = use.name;
 							activationMethod.Value = use.activation;
 							
@@ -291,7 +307,7 @@ namespace ICSharpCode.UsageDataCollector
 						cmd.Parameters.Add(id = new SQLiteParameter());
 						while (delayedEnd.Count > 0) {
 							FeatureUse use = delayedEnd.Dequeue();
-							endTime.Value = use.endTime.ToString("yyyy-MM-dd hh:mm:ss", CultureInfo.InvariantCulture);
+							endTime.Value = TimeToString(use.endTime);
 							id.Value = use.rowId;
 							cmd.ExecuteNonQuery();
 						}
@@ -424,8 +440,9 @@ namespace ICSharpCode.UsageDataCollector
 				// first, insert the exception (it's most important to have)
 				using (SQLiteCommand cmd = this.connection.CreateCommand()) {
 					cmd.CommandText = "INSERT INTO Exceptions (session, time, type, stackTrace)" +
-						" VALUES (?, datetime('now'), ?, ?);";
+						" VALUES (?, ?, ?, ?);";
 					cmd.Parameters.Add(new SQLiteParameter { Value = sessionID });
+					cmd.Parameters.Add(new SQLiteParameter { Value = TimeToString(GetNow()) });
 					cmd.Parameters.Add(new SQLiteParameter { Value = exceptionType });
 					cmd.Parameters.Add(new SQLiteParameter { Value = stacktrace });
 					cmd.ExecuteNonQuery();
@@ -458,14 +475,15 @@ namespace ICSharpCode.UsageDataCollector
 	/// </summary>
 	public sealed class FeatureUse
 	{
-		internal readonly DateTime startTime = DateTime.UtcNow;
+		internal readonly DateTime startTime;
 		internal DateTime endTime;
 		internal string name, activation;
 		internal long rowId;
-		UsageDataSessionWriter writer;
+		readonly UsageDataSessionWriter writer;
 		
-		internal FeatureUse(UsageDataSessionWriter writer)
+		internal FeatureUse(UsageDataSessionWriter writer, DateTime startTime)
 		{
+			this.startTime = startTime;
 			this.writer = writer;
 		}