profiling: cache symbol key interval

To resolve symbols, the method retrieveSymbolKeyAt will query a symbol
key attribute for every interval in a query2d. This create a significant
overhead that can easily be avoided if we cache this interval. For all
current use cases, the symbol key interval is unique for each trace.

Signed-off-by: Arnaud Fiorini <[email protected]>

Author: arfio

analysis/org.eclipse.tracecompass.analysis.profiling.core/src/org/eclipse/tracecompass/internal/analysis/profiling/core/instrumented/InstrumentedCallStackElement.java

@@ -53,6 +53,7 @@ public class InstrumentedCallStackElement extends CallStackElement {
     private final int fQuark;
     private final IHostIdResolver fHostResolver;
     private final @Nullable IThreadIdResolver fThreadIdResolver;
+    private @Nullable ITmfStateInterval fSymbolKeyInterval = null;
     private final Map<Integer, ICallStackElement> fNextElements = new HashMap<>();
 
     private @Nullable CallStack fCallstack = null;
@@ -178,13 +179,18 @@ private static Collection<ICallStackElement> getNextElements(InstrumentedGroupDe
     public int retrieveSymbolKeyAt(long startTime) {
         int processId = CallStackElement.DEFAULT_SYMBOL_KEY;
         if (fQuark != ITmfStateSystem.ROOT_ATTRIBUTE) {
+            ITmfStateInterval symbolKeyInterval = fSymbolKeyInterval;
+            if (symbolKeyInterval != null && symbolKeyInterval.intersects(startTime)) {
+                return symbolKeyInterval.getValueInt();
+            }
             try {
                 // Query a time that is within the bounds of the state system
                 long start = Math.max(fStateSystem.getStartTime(), startTime);
                 start = Math.max(start, fStateSystem.getCurrentEndTime());
 
                 // Query the value of the quark at the requested time
                 ITmfStateInterval interval = fStateSystem.querySingleState(start, fQuark);
+                fSymbolKeyInterval = interval;
                 ITmfStateValue processStateValue = interval.getStateValue();
                 // If the state value is an integer, assume it is the symbol we
                 // are looking for