server: read first event when opening a trace

This will initialize the start time of the trace object which is needed
when initializing a state system.

[Fixed] Uninitialized start time of trace in trace server

Change-Id: If6236e7fd28e30e7a1d58c84b4b69f130652c380
Signed-off-by: Bernd Hufmann <Bernd.Hufmann@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/150955
Tested-by: CI Bot
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>

trace-server/org.eclipse.tracecompass.incubator.trace.server.jersey.rest.core/src/org/eclipse/tracecompass/incubator/internal/trace/server/jersey/rest/core/services/TraceManagerService.java

@@ -50,6 +50,7 @@
 import org.eclipse.tracecompass.tmf.core.signal.TmfSignalManager;
 import org.eclipse.tracecompass.tmf.core.signal.TmfTraceClosedSignal;
 import org.eclipse.tracecompass.tmf.core.signal.TmfTraceOpenedSignal;
+import org.eclipse.tracecompass.tmf.core.trace.ITmfContext;
 import org.eclipse.tracecompass.tmf.core.trace.ITmfTrace;
 import org.eclipse.tracecompass.tmf.core.trace.TmfTraceManager;
 import org.eclipse.tracecompass.tmf.core.trace.experiment.TmfExperiment;
@@ -130,6 +131,11 @@ private ITmfTrace put(String path, String name, String typeID)
         ITmfTrace trace = helper.getTraceClass().newInstance();
         trace.initTrace(resource, path, ITmfEvent.class, name, typeID);
         trace.indexTrace(false);
+        // read first event to make sure start time is initialized
+        ITmfContext ctx = trace.seekEvent(0);
+        trace.getNext(ctx);
+        ctx.dispose();
+
         TmfSignalManager.dispatchSignal(new TmfTraceOpenedSignal(this, trace, null));
         return trace;
     }
@@ -212,7 +218,6 @@ public Response deleteTrace(@PathParam("uuid") @NotNull UUID uuid) {
             return Response.status(Status.NOT_FOUND).build();
         }
         TmfSignalManager.dispatchSignal(new TmfTraceClosedSignal(this, trace));
-        TmfTraceManager.deleteSupplementaryFolder(trace);
         trace.dispose();
         try {
             IResource resource = trace.getResource();