Mappings: Restrict murmur3 field type to sane options

Disabling doc values or trying to index hash values are not
correct uses of this the murmur3 field type, and just cause
problems.  This disallows changing doc values or index options
for 2.0+.

closes elastic#10465

docs/reference/migration/migrate_2_0.asciidoc

@@ -302,6 +302,10 @@ the user-friendly representation of boolean fields: `false`/`true`:
 ]
 ---------------
 
+=== Murmur3 Fields
+Fields of type `murmur3` can no longer change `doc_values` or `index` setting.
+They are always stored with doc values, and not indexed.
+
 === Codecs
 
 It is no longer possible to specify per-field postings and doc values formats

src/main/java/org/elasticsearch/index/mapper/core/Murmur3FieldMapper.java

@@ -22,6 +22,7 @@
 import org.apache.lucene.document.Field;
 import org.apache.lucene.document.FieldType;
 import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.Version;
 import org.elasticsearch.common.Explicit;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.hash.MurmurHash3;
@@ -35,6 +36,7 @@
 import java.util.List;
 import java.util.Map;
 
+import static org.elasticsearch.common.xcontent.support.XContentMapValues.nodeBooleanValue;
 import static org.elasticsearch.index.mapper.MapperBuilders.murmur3Field;
 import static org.elasticsearch.index.mapper.core.TypeParsers.parseNumberField;
 
@@ -69,6 +71,17 @@ public static class TypeParser implements Mapper.TypeParser {
         @SuppressWarnings("unchecked")
         public Mapper.Builder parse(String name, Map<String, Object> node, ParserContext parserContext) throws MapperParsingException {
             Builder builder = murmur3Field(name);
+
+            // tweaking these settings is no longer allowed, the entire purpose of murmur3 fields is to store a hash
+            if (parserContext.indexVersionCreated().onOrAfter(Version.V_2_0_0)) {
+                if (node.get("doc_values") != null) {
+                    throw new MapperParsingException("Setting [doc_values] cannot be modified for field [" + name + "]");
+                }
+                if (node.get("index") != null) {
+                    throw new MapperParsingException("Setting [index] cannot be modified for field [" + name + "]");
+                }
+            }
+
             parseNumberField(builder, name, node, parserContext);
             // Because this mapper extends LongFieldMapper the null_value field will be added to the JSON when transferring cluster state
             // between nodes so we have to remove the entry here so that the validation doesn't fail

src/test/java/org/elasticsearch/index/mapper/core/Murmur3FieldMapperTests.java

@@ -0,0 +1,132 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.index.mapper.core;
+
+import org.apache.lucene.index.IndexOptions;
+import org.elasticsearch.Version;
+import org.elasticsearch.cluster.metadata.IndexMetaData;
+import org.elasticsearch.common.settings.ImmutableSettings;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.xcontent.XContentFactory;
+import org.elasticsearch.index.IndexService;
+import org.elasticsearch.index.mapper.DocumentMapper;
+import org.elasticsearch.index.mapper.DocumentMapperParser;
+import org.elasticsearch.index.mapper.Mapper;
+import org.elasticsearch.index.mapper.MapperParsingException;
+import org.elasticsearch.test.ElasticsearchSingleNodeTest;
+import org.junit.Before;
+
+public class Murmur3FieldMapperTests extends ElasticsearchSingleNodeTest {
+
+    IndexService indexService;
+    DocumentMapperParser parser;
+
+    @Before
+    public void before() {
+        indexService = createIndex("test");
+        parser = indexService.mapperService().documentMapperParser();
+    }
+
+    public void testDocValuesSettingNotAllowed() throws Exception {
+        String mapping = XContentFactory.jsonBuilder().startObject().startObject("type")
+            .startObject("properties").startObject("field")
+                .field("type", "murmur3")
+                .field("doc_values", false)
+            .endObject().endObject().endObject().endObject().string();
+        try {
+            parser.parse(mapping);
+            fail("expected a mapper parsing exception");
+        } catch (MapperParsingException e) {
+            assertTrue(e.getMessage().contains("Setting [doc_values] cannot be modified"));
+        }
+
+        // even setting to the default is not allowed, the setting is invalid
+        mapping = XContentFactory.jsonBuilder().startObject().startObject("type")
+            .startObject("properties").startObject("field")
+                .field("type", "murmur3")
+                .field("doc_values", true)
+            .endObject().endObject().endObject().endObject().string();
+        try {
+            parser.parse(mapping);
+            fail("expected a mapper parsing exception");
+        } catch (MapperParsingException e) {
+            assertTrue(e.getMessage().contains("Setting [doc_values] cannot be modified"));
+        }
+    }
+
+    public void testIndexSettingNotAllowed() throws Exception {
+        String mapping = XContentFactory.jsonBuilder().startObject().startObject("type")
+            .startObject("properties").startObject("field")
+                .field("type", "murmur3")
+                .field("index", "not_analyzed")
+            .endObject().endObject().endObject().endObject().string();
+        try {
+            parser.parse(mapping);
+            fail("expected a mapper parsing exception");
+        } catch (MapperParsingException e) {
+            assertTrue(e.getMessage().contains("Setting [index] cannot be modified"));
+        }
+
+        // even setting to the default is not allowed, the setting is invalid
+        mapping = XContentFactory.jsonBuilder().startObject().startObject("type")
+            .startObject("properties").startObject("field")
+                .field("type", "murmur3")
+                .field("index", "no")
+            .endObject().endObject().endObject().endObject().string();
+        try {
+            parser.parse(mapping);
+            fail("expected a mapper parsing exception");
+        } catch (MapperParsingException e) {
+            assertTrue(e.getMessage().contains("Setting [index] cannot be modified"));
+        }
+    }
+
+    public void testDocValuesSettingBackcompat() throws Exception {
+        Settings settings = ImmutableSettings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.V_1_4_2.id).build();
+        indexService = createIndex("test_bwc", settings);
+        parser = indexService.mapperService().documentMapperParser();
+        String mapping = XContentFactory.jsonBuilder().startObject().startObject("type")
+            .startObject("properties").startObject("field")
+                .field("type", "murmur3")
+                .field("doc_values", false)
+            .endObject().endObject().endObject().endObject().string();
+
+        DocumentMapper docMapper = parser.parse(mapping);
+        Murmur3FieldMapper mapper = (Murmur3FieldMapper)docMapper.mappers().getMapper("field");
+        assertFalse(mapper.hasDocValues());
+    }
+
+    public void testIndexSettingBackcompat() throws Exception {
+        Settings settings = ImmutableSettings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.V_1_4_2.id).build();
+        indexService = createIndex("test_bwc", settings);
+        parser = indexService.mapperService().documentMapperParser();
+        String mapping = XContentFactory.jsonBuilder().startObject().startObject("type")
+            .startObject("properties").startObject("field")
+            .field("type", "murmur3")
+            .field("index", "not_analyzed")
+            .endObject().endObject().endObject().endObject().string();
+
+        DocumentMapper docMapper = parser.parse(mapping);
+        Murmur3FieldMapper mapper = (Murmur3FieldMapper)docMapper.mappers().getMapper("field");
+        assertEquals(IndexOptions.DOCS, mapper.fieldType().indexOptions());
+    }
+
+    // TODO: add more tests
+}