From 591f9522b5056bc924e998a1acb4bcc156211b67 Mon Sep 17 00:00:00 2001
From: Ramesh Reddy <rareddy@jboss.org>
Date: Fri, 9 Sep 2016 19:00:57 -0500
Subject: [PATCH] OLINGO-1009: refining the cycle detection logic

---
 .../core/serializer/json/ODataJsonSerializer.java      |  8 +++-----
 .../server/core/serializer/xml/ODataXmlSerializer.java | 10 +++++-----
 2 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/ODataJsonSerializer.java b/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/ODataJsonSerializer.java
index f6e6015f3..edca2e436 100644
--- a/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/ODataJsonSerializer.java
+++ b/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/ODataJsonSerializer.java
@@ -323,13 +323,11 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
       final SelectOption select, final boolean onlyReference, Set<String> ancestors, final JsonGenerator json)
       throws IOException, SerializerException {
     boolean cycle = false;
-    if (expand != null && cycleDetected(ancestors, getEntityId(entity))) {
-        cycle = true;
-    } else {
+    if (expand != null) {
       if (ancestors == null) {
         ancestors = new HashSet<String>();
       }
-      ancestors.add(getEntityId(entity));
+      cycle = !ancestors.add(getEntityId(entity));
     }
     try {
       json.writeStartObject();
@@ -383,7 +381,7 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
       }
       json.writeEndObject();
     } finally {
-      if (!cycle && ancestors != null) {
+      if (expand != null && !cycle && ancestors != null) {
         ancestors.remove(getEntityId(entity));
       }
     }
diff --git a/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/xml/ODataXmlSerializer.java b/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/xml/ODataXmlSerializer.java
index 56ee3918d..d8acbf451 100644
--- a/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/xml/ODataXmlSerializer.java
+++ b/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/xml/ODataXmlSerializer.java
@@ -440,13 +440,11 @@ public class ODataXmlSerializer extends AbstractODataSerializer {
       final XMLStreamWriter writer, final boolean top, final boolean writeOnlyRef, Set<String> ancestors)
       throws XMLStreamException, SerializerException {
     boolean cycle = false;
-    if (expand != null && cycleDetected(ancestors, getEntityId(entity))) {
-      cycle = true;
-    } else {
+    if (expand != null) {
       if (ancestors == null) {
         ancestors = new HashSet<String>();
       }
-      ancestors.add(getEntityId(entity));
+      cycle = !ancestors.add(getEntityId(entity));
     }
 
     if (cycle || writeOnlyRef) {
@@ -531,7 +529,9 @@ public class ODataXmlSerializer extends AbstractODataSerializer {
       
       writer.writeEndElement(); // entry
     } finally {
-      ancestors.remove(getEntityId(entity));
+      if (!cycle && ancestors != null) {
+        ancestors.remove(getEntityId(entity));
+      }
     }
   }