Merge pull request #881 from ascrutae/fix/entry-span-issue

[Agent] fix create entry span failure

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/TracingContext.java

@@ -248,35 +248,33 @@ public class TracingContext implements AbstractTracerContext {
         AbstractSpan entrySpan;
         final AbstractSpan parentSpan = peek();
         final int parentSpanId = parentSpan == null ? -1 : parentSpan.getSpanId();
-        if (parentSpan == null) {
+        if (parentSpan != null && parentSpan.isEntry()) {
             entrySpan = (AbstractTracingSpan)DictionaryManager.findOperationNameCodeSection()
                 .findOnly(segment.getApplicationId(), operationName)
                 .doInCondition(new PossibleFound.FoundAndObtain() {
                     @Override public Object doProcess(int operationId) {
-                        return new EntrySpan(spanIdGenerator++, parentSpanId, operationId);
+                        return parentSpan.setOperationId(operationId);
                     }
                 }, new PossibleFound.NotFoundAndObtain() {
                     @Override public Object doProcess() {
-                        return new EntrySpan(spanIdGenerator++, parentSpanId, operationName);
+                        return parentSpan.setOperationName(operationName);
                     }
                 });
-            entrySpan.start();
-            return push(entrySpan);
-        } else if (parentSpan.isEntry()) {
+            return entrySpan.start();
+        } else {
             entrySpan = (AbstractTracingSpan)DictionaryManager.findOperationNameCodeSection()
                 .findOnly(segment.getApplicationId(), operationName)
                 .doInCondition(new PossibleFound.FoundAndObtain() {
                     @Override public Object doProcess(int operationId) {
-                        return parentSpan.setOperationId(operationId);
+                        return new EntrySpan(spanIdGenerator++, parentSpanId, operationId);
                     }
                 }, new PossibleFound.NotFoundAndObtain() {
                     @Override public Object doProcess() {
-                        return parentSpan.setOperationName(operationName);
+                        return new EntrySpan(spanIdGenerator++, parentSpanId, operationName);
                     }
                 });
-            return entrySpan.start();
-        } else {
-            throw new IllegalStateException("The Entry Span can't be the child of Non-Entry Span");
+            entrySpan.start();
+            return push(entrySpan);
         }
     }