Avoid restarting history after rebrowse in some cases (#871)

If we discover new nodes there's no real reason to restart history.

Author: einarmo

Extractor/History/HistoryReader.cs

@@ -332,16 +332,17 @@ public void AddStates(IEnumerable<VariableExtractionState> varStates, IEnumerabl
         {
             lock (statesLock)
             {
+                bool anyAdded = false;
                 foreach (var state in varStates.Where(s => s.FrontfillEnabled))
                 {
-                    activeVarStates[state.SourceId] = state;
+                    anyAdded |= activeVarStates.TryAdd(state.SourceId, state);
                 }
 
                 foreach (var state in eventStates.Where(s => s.FrontfillEnabled))
                 {
-                    activeEventStates[state.SourceId] = state;
+                    anyAdded |= activeEventStates.TryAdd(state.SourceId, state);
                 }
-                if (state.IsGood)
+                if (state.IsGood && anyAdded)
                 {
                     stateChangedEvent.Set();
                 }

Test/Integration/EventTests.cs

@@ -197,6 +197,8 @@ async Task Reset()
                 extractor.State.Clear();
                 var reader = (HistoryReader)extractor.GetType().GetField("historyReader", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(extractor);
                 reader.AddIssue(HistoryReader.StateIssue.NodeHierarchyRead);
+                ((Dictionary<NodeId, VariableExtractionState>)reader.GetType().GetField("activeVarStates", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(reader)).Clear();
+                ((Dictionary<NodeId, EventExtractionState>)reader.GetType().GetField("activeEventStates", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(reader)).Clear();
                 await tester.RemoveSubscription(extractor, SubscriptionName.Events);
             }
 

Test/Unit/CDFPusherTest.cs

@@ -1266,6 +1266,8 @@ public async Task TestCDFAsSourceData()
             string oldTimeseries = System.Text.Json.JsonSerializer.Serialize(handler.TimeseriesRaw);
             extractor.ClearKnownSubscriptions();
             var reader = (HistoryReader)extractor.GetType().GetField("historyReader", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(extractor);
+            ((Dictionary<NodeId, VariableExtractionState>)reader.GetType().GetField("activeVarStates", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(reader)).Clear();
+            ((Dictionary<NodeId, EventExtractionState>)reader.GetType().GetField("activeEventStates", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(reader)).Clear();
             reader.AddIssue(HistoryReader.StateIssue.NodeHierarchyRead);
             await extractor.RunExtractor(true);
             Assert.True(extractor.State.NodeStates.Count > 0);

manifest.yml

@@ -67,6 +67,11 @@ schema:
    - "https://raw.githubusercontent.com/"
 
 versions:
+  "2.28.2":
+    description: Avoid restarting history after rebrowse if no new nodes were discovered.
+    changelog:
+      fixed:
+        - Fix issue causing history to be restarted if rebrowse was triggered but no new nodes were discovered.
   "2.38.1":
     description: Fix issue causing the extractor to stop pushing datapoints if pushing nodes to CDF during rebrowse fails.
     changelog: