Fixed issue #799 - Added break to possibly-infinite loop in CompositeException.attachCallingThreadStack

Author: mattrjacobs

rxjava-core/src/main/java/rx/util/CompositeException.java

@@ -18,7 +18,9 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 /**
  * Exception that is a composite of 1 or more other exceptions.
@@ -84,9 +86,16 @@ private static String getStackTraceAsString(StackTraceElement[] stack) {
         return s.toString();
     }
 
-    private static void attachCallingThreadStack(Throwable e, Throwable cause) {
+    /* package-private */ static void attachCallingThreadStack(Throwable e, Throwable cause) {
+        Set<Throwable> seenCauses = new HashSet<Throwable>();
+
         while (e.getCause() != null) {
             e = e.getCause();
+            if (seenCauses.contains(e.getCause())) {
+                break;
+            } else {
+                seenCauses.add(e.getCause());
+            }
         }
         // we now have 'e' as the last in the chain
         try {
@@ -98,12 +107,13 @@ private static void attachCallingThreadStack(Throwable e, Throwable cause) {
         }
     }
 
-    private final static class CompositeExceptionCausalChain extends RuntimeException {
+    /* package-private */ final static class CompositeExceptionCausalChain extends RuntimeException {
         private static final long serialVersionUID = 3875212506787802066L;
+        /* package-private */ static String MESSAGE = "Chain of Causes for CompositeException In Order Received =>";
 
         @Override
         public String getMessage() {
-            return "Chain of Causes for CompositeException In Order Received =>";
+            return MESSAGE;
         }
     }
 

rxjava-core/src/test/java/rx/util/CompositeExceptionTest.java

@@ -0,0 +1,70 @@
+/**
+ * Copyright 2013 Netflix, Inc.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package rx.util;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CompositeExceptionTest {
+
+    private final Throwable ex1 = new Throwable("Ex1");
+    private final Throwable ex2 = new Throwable("Ex2", ex1);
+    private final Throwable ex3 = new Throwable("Ex3", ex2);
+
+    private final CompositeException compositeEx;
+
+    public CompositeExceptionTest() {
+        List<Throwable> throwables = new ArrayList<Throwable>();
+        throwables.add(ex1);
+        throwables.add(ex2);
+        throwables.add(ex3);
+        compositeEx = new CompositeException(throwables);
+    }
+
+    @Test
+    public void testAttachCallingThreadStackParentThenChild() {
+        CompositeException.attachCallingThreadStack(ex1, ex2);
+        assertEquals("Ex2", ex1.getCause().getMessage());
+    }
+
+    @Test
+    public void testAttachCallingThreadStackChildThenParent() {
+        CompositeException.attachCallingThreadStack(ex2, ex1);
+        assertEquals("Ex1", ex2.getCause().getMessage());
+    }
+
+    @Test
+    public void testAttachCallingThreadStackAddComposite() {
+        CompositeException.attachCallingThreadStack(ex1, compositeEx);
+        assertEquals("Ex2", ex1.getCause().getMessage());
+    }
+
+    @Test
+    public void testAttachCallingThreadStackAddToComposite() {
+        CompositeException.attachCallingThreadStack(compositeEx, ex1);
+        assertEquals(CompositeException.CompositeExceptionCausalChain.MESSAGE, compositeEx.getCause().getMessage());
+    }
+
+    @Test
+    public void testAttachCallingThreadStackAddCompositeToItself() {
+        CompositeException.attachCallingThreadStack(compositeEx, compositeEx);
+        assertEquals(CompositeException.CompositeExceptionCausalChain.MESSAGE, compositeEx.getCause().getMessage());
+    }
+}