HPCC-35963: Fixup evtool index plot

common/eventconsumption/eventindexplot.cpp

@@ -87,7 +87,7 @@ bool CIndexPlotOp::visitEvent(CEvent& event)
         break;
     case EventIndexCacheMiss:
         if (valueSelector == ValueSelector::CacheMisses)
-            cellValue = 1;
+            cellValue++;
         break;
     default:
         break;
@@ -418,6 +418,7 @@ bool CIndexPlotOp::doXAxis(LinkChanges& linkChanges, size_t yAxisIdx)
         // prepare for next iteration
         cellIdx++;
         linkChanges.pop_back();
+        postTraversalReset();
     }
     outputEOLN();
 

common/eventconsumption/eventoperation.cpp

@@ -98,6 +98,12 @@ const EventFileProperties& CEventConsumingOp::queryIteratorProperties()
     return cachedSource->queryFileProperties();
 }
 
+void CEventConsumingOp::postTraversalReset()
+{
+    metaState->clearAll();
+    cachedSource.clear();
+}
+
 bool CEventConsumingOp::traverseEvents(IEventVisitor& visitor)
 {
     // Ensure iterator is created and cached

common/eventconsumption/eventoperation.h

@@ -52,6 +52,11 @@ class event_decl CEventConsumingOp : public CInterface
     // For multiplexed sources, properties reflect aggregated/ambiguous values.
     const EventFileProperties& queryIteratorProperties();
 
+    // Resets the operation state following an event traversal. To be invoked by subclasses
+    // that intend to traverse events multiple times, when those subclasses are finished with
+    // the current state.
+    virtual void postTraversalReset();
+
 protected:
     Owned<CMetaInfoState> metaState;
     std::set<std::string> inputPaths;