HY-51: decoder reset missing to set next to null in groups decoder,…

… leaving ghosts references when parsing new message with the same decoder instance - issue 525.

artio-codecs/src/main/java/uk/co/real_logic/artio/dictionary/generation/DecoderGenerator.java

@@ -416,21 +416,28 @@ protected String resetGroup(final Entry entry)
                 "    {\n" +
                 "        for (final %2$s %6$s : %5$s.iterator())\n" +
                 "        {\n" +
-                "            %6$s.reset();\n" +
                 "            if (%6$s.next() == null)\n" +
                 "            {\n" +
+                "                %6$s.reset();\n" +
                 "                break;\n" +
                 "            }\n" +
+                "            else\n" +
+                "            {\n" +
+                "                %6$s.reset();\n" +
+                "            }\n" +
                 "        }\n" +
                 "        %3$s = MISSING_INT;\n" +
                 "        has%4$s = false;\n" +
+                "        %7$s = null;\n" +
                 "    }\n\n",
                 resetMethod,
                 decoderClassName(name),
                 formatPropertyName(numberField.name()),
                 numberField.name(),
                 iteratorFieldName(group),
-                formatPropertyName(decoderClassName(name)));
+                formatPropertyName(decoderClassName(name)),
+                formatPropertyName(name)
+            );
         }
     }
 
@@ -484,6 +491,9 @@ private String additionalReset(final boolean isGroup)
     {
         return
             "        buffer = null;\n" +
+              (isGroup ?
+            "        next = null;\n" : ""
+              ) +
             "        if (" + CODEC_VALIDATION_ENABLED + ")\n" +
             "        {\n" +
             "            invalidTagId = Decoder.NO_ERROR;\n" +

artio-codecs/src/test/java/uk/co/real_logic/artio/dictionary/ExampleDictionary.java

@@ -272,7 +272,7 @@ public final class ExampleDictionary
         "8=FIX.4.4\0019=77\00135=0\001115=abc\001116=2\001117=1.1\001127=19700101-00:00:00.001" +
         "\001120=2\001121=1\001122=2\001123=1\001123=2\001121=2\001122=2\001123=3\001123=4\00110=063\001";
 
-    public static final String MULTI_ENTRY_NESTED_GROUP_MESSAGE_WITHOUT_NESTED_FIELDS =
+    public static final String MULTI_ENTRY_EG_GROUP_MESSAGE_WITHOUT_NESTED_GROUPS =
         "8=FIX.4.4\0019=77\00135=0\001115=abc\001116=2\001117=1.1\001127=19700101-00:00:00.001" +
         "\001120=2\001121=1\001121=2\00110=063\001";
 

artio-codecs/src/test/java/uk/co/real_logic/artio/dictionary/generation/AbstractDecoderGeneratorTest.java

@@ -33,6 +33,7 @@
 import java.lang.reflect.Method;
 import java.nio.charset.StandardCharsets;
 import java.util.*;
+import java.util.function.Consumer;
 import java.util.function.Function;
 
 import static java.lang.reflect.Modifier.isAbstract;
@@ -838,14 +839,21 @@ public void shouldReasonablyValidateGroupNumbersLessThanTheNumberOfElementsInThe
         assertInvalid(decoder, INCORRECT_NUMINGROUP_COUNT_FOR_REPEATING_GROUP, 120);
     }
 
-    //TODO this test was added to guide the bugfix
+    //this test was added for issue #525
     @Test
     public void shouldReasonablyValidateGroupNumbersLessThanTheNumberOfElementsInTheGroupList() throws Exception
     {
-        final Decoder decoder = decodeHeartbeatWithRejectingUnknownFields(
-            REPEATING_GROUP_MESSAGE_WITH_THREE, REPEATING_GROUP_MESSAGE_WITH_TOO_HIGH_NUMBER_FIELD);
+        final Decoder decoder = (Decoder)heartbeatWithRejectingUnknownFields.getConstructor().newInstance();
 
-//        assertInvalid(decoder, INCORRECT_NUMINGROUP_COUNT_FOR_REPEATING_GROUP, 120);
+        decodeHeartbeatWithRejectingUnknownFields(
+            decoder, this::assertValid, REPEATING_GROUP_MESSAGE_WITH_THREE);
+        decodeHeartbeatWithRejectingUnknownFields(
+            decoder, decoder1 ->
+            assertInvalid(decoder1,
+            INCORRECT_NUMINGROUP_COUNT_FOR_REPEATING_GROUP,
+            120), REPEATING_GROUP_MESSAGE_WITH_TOO_HIGH_NUMBER_FIELD);
+        decodeHeartbeatWithRejectingUnknownFields(
+            decoder, this::assertValid, REPEATING_GROUP_MESSAGE_WITH_THREE);
     }
 
     @Test
@@ -1167,15 +1175,29 @@ public void shouldResetAllNestedRepeatingGroupEntries() throws Exception
 
         decoder.reset();
 
-        decode(MULTI_ENTRY_NESTED_GROUP_MESSAGE_WITHOUT_NESTED_FIELDS, decoder);
+        decode(MULTI_ENTRY_EG_GROUP_MESSAGE_WITHOUT_NESTED_GROUPS, decoder);
         assertEquals(2, getNoEgGroupGroupCounter(decoder));
 
         group = getEgGroup(decoder);
+        assertNull(getNestedGroup(group));
+
+        group = next(group);
+        assertNull(getNestedGroup(group));
+    }
+
+    @Test
+    public void shouldHaveAllNestedRepeatingGroupEntriesNullifiedWhenMessageDoesNotHaveIt() throws Exception
+    {
+        Object group;
 
-        assertNestedRepeating(group, 1, CodecUtil.MISSING_INT, CodecUtil.MISSING_INT);
+        final Decoder decoder = decodeHeartbeat(MULTI_ENTRY_EG_GROUP_MESSAGE_WITHOUT_NESTED_GROUPS);
+        assertEquals(2, getNoEgGroupGroupCounter(decoder));
+
+        group = getEgGroup(decoder);
+        assertNull(getNestedGroup(group));
 
         group = next(group);
-        assertNestedRepeating(group, 2, CodecUtil.MISSING_INT, CodecUtil.MISSING_INT);
+        assertNull(getNestedGroup(group));
     }
 
     @Test
@@ -1889,13 +1911,12 @@ Decoder decodeHeartbeatWithoutValidation(final String example) throws Exception
         return decoder;
     }
 
-    private Decoder decodeHeartbeatWithRejectingUnknownFields(final String... example) throws Exception
+    private Decoder decodeHeartbeatWithRejectingUnknownFields(final Decoder decoder,
+        final Consumer<Decoder> consumer,
+        final String example)
     {
-        final Decoder decoder = (Decoder)heartbeatWithRejectingUnknownFields.getConstructor().newInstance();
-        for (final String s : example)
-        {
-            decode(s, decoder);
-        }
+        decode(example, decoder);
+        consumer.accept(decoder);
         return decoder;
     }
 
@@ -1909,6 +1930,7 @@ private Decoder decodeHeartbeatWithRejectingUnknownFields(final String example)
     void decode(final String example, final Decoder decoder)
     {
         buffer.putAscii(1, example);
+        decoder.reset();
         decoder.decode(buffer, 1, example.length());
     }