Fix #357 properly. Finally!

release-notes/VERSION

@@ -12,6 +12,8 @@ Project: jackson-databind
 #291: @JsonTypeInfo with As.EXTERNAL_PROPERTY doesn't work if external type property
   is referenced more than once
  (reported by Starkom@github)
+#357: StackOverflowError with contentConverter that returns array type
+ (reported by Florian S)
 #476: Allow "Serialize as POJO" using `@JsonFormat(shape=Shape.OBJECT)` class annotation
 #507: Support for default `@JsonView` for a class
  (suggested by Mark W)

src/main/java/com/fasterxml/jackson/databind/ser/std/StdDelegatingSerializer.java

@@ -160,15 +160,11 @@ public void serialize(Object value, JsonGenerator gen, SerializerProvider provid
             provider.defaultSerializeNull(gen);
             return;
         }
-System.err.println(" delegating.serialize. value: "+value.getClass());
-
         // 02-Apr-2015, tatu: As per [databind#731] may need to do dynamic lookup
         JsonSerializer<Object> ser = _delegateSerializer;
         if (ser == null) {
-System.err.println("DEBUG: dynamic lookup for delegator... ");            
             ser = _findSerializer(delegateValue, provider);
         }
-System.err.println(" delegating.serialize with -> "+ser);
         ser.serialize(delegateValue, gen, provider);
     }
 

src/main/java/com/fasterxml/jackson/databind/ser/std/StdSerializer.java

@@ -3,8 +3,8 @@
 import java.io.IOException;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Type;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.IdentityHashMap;
+import java.util.Map;
 
 import com.fasterxml.jackson.annotation.JsonFormat;
 import com.fasterxml.jackson.annotation.JsonInclude;
@@ -34,6 +34,14 @@ public abstract class StdSerializer<T>
 {
     private static final long serialVersionUID = 1L;
 
+    /**
+     * Key used for storing a lock object to prevent infinite recursion when
+     * constructing converting serializers.
+     *
+     * @since 2.9
+     */
+    private final static Object KEY_CONTENT_CONVERTER_LOCK = new Object();
+
     /**
      * Nominal type supported, usually declared type of
      * property for which serializer is used.
@@ -355,30 +363,29 @@ protected JsonSerializer<?> findContextualConvertingSerializer(SerializerProvide
     {
         // 08-Dec-2016, tatu: to fix [databind#357], need to prevent recursive calls for
         //     same property
-        /*
         @SuppressWarnings("unchecked")
-        Set<Object> conversions = (Set<Object>) provider.getAttribute(CONTENT_CONVERTER_LOCK);
+        Map<Object,Object> conversions = (Map<Object,Object>) provider.getAttribute(KEY_CONTENT_CONVERTER_LOCK);
         if (conversions != null) {
-            if (conversions.contains(property)) {
+            Object lock = conversions.get(property);
+            if (lock != null) {
                 return existingSerializer;
             }
         } else {
-            conversions = new HashSet<>();
-            provider.setAttribute(CONTENT_CONVERTER_LOCK, provider);
+            conversions = new IdentityHashMap<>();
+            provider.setAttribute(KEY_CONTENT_CONVERTER_LOCK, conversions);
         }
+        conversions.put(property, Boolean.TRUE);
         try {
-        } finally {
-        }
-        */
             JsonSerializer<?> ser = findConvertingContentSerializer(provider, property, existingSerializer);
             if (ser != null) {
                 return provider.handleSecondaryContextualization(ser, property);
             }
+        } finally {
+            conversions.remove(property);
+        }
         return existingSerializer;
     }
 
-//    private final static Object CONTENT_CONVERTER_LOCK = new Object();
-
     /**
      * @deprecated Since 2.9 use {link {@link #findContextualConvertingSerializer} instead
      */

src/test/java/com/fasterxml/jackson/databind/convert/TestConvertingDeserializer.java

@@ -4,6 +4,7 @@
 import java.util.*;
 
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 import com.fasterxml.jackson.databind.util.StdConverter;
 
 public class TestConvertingDeserializer
@@ -99,6 +100,21 @@ static class LowerCaseTextArray {
         public String[] texts;
     }
 
+    // [databind#357]
+    static class Value { }
+
+    static class ListWrapper {
+        @JsonSerialize(contentConverter = ValueToStringListConverter.class)
+        public List<Value> list = Arrays.asList(new Value());
+    }
+
+    static class ValueToStringListConverter extends StdConverter<Value, List<String>> {
+        @Override
+        public List<String> convert(Value value) {
+            return Arrays.asList("Hello world!");
+        }
+    }
+
     // for [databind#795]
 
     static class ToNumberConverter extends StdConverter<String,Number>
@@ -114,7 +130,7 @@ static class Issue795Bean
         @JsonDeserialize(converter=ToNumberConverter.class)
         public Number value;
     }
-    
+
     /*
     /**********************************************************
     /* Test methods
@@ -198,6 +214,12 @@ public void testPropertyAnnotationForMaps() throws Exception
         assertEquals(2, p.y);
     }
 
+    // [databind#357]
+    public void testConverterForList357() throws Exception {
+        String json = objectWriter().writeValueAsString(new ListWrapper());
+        assertEquals("{\"list\":[[\"Hello world!\"]]}", json);
+    }
+
     // [databind#795]
     public void testConvertToAbstract() throws Exception
     {