Scripting: cleanup ScriptService & friends in preparation for #6418

- Added NAME constants for each script language, avoiding to repeat the same strings all over the place.
- Simplified `compile` method signatures by removing a couple of variants. Note that all of these signatures are going to change again with #6418 as in order to compile/execute a script the caller will need to specify which operation is attempting to execute the script, info that will be provided as an additional mandatory argument.
- Removed double call to ScriptService#verifyDynamicScripting for every indexed or dynamic script.
- Decreased ScriptService inner classes visibility to private (CacheKey, IndexedScript, ApplySettings)
- Moved ScriptService inner classes to the bottom of the class, I think it makes it more readable.
- Resolved some compiler warnings

Closes #9992

Author: javanna

src/main/java/org/elasticsearch/index/query/ScriptFilterParser.java

@@ -68,7 +68,7 @@ public Filter parse(QueryParseContext parseContext) throws IOException, QueryPar
         CacheKeyFilter.Key cacheKey = null;
         // also, when caching, since its isCacheable is false, will result in loading all bit set...
         String script = null;
-        String scriptLang = null;
+        String scriptLang;
         Map<String, Object> params = null;
 
         String filterName = null;
@@ -129,12 +129,9 @@ public static class ScriptFilter extends Filter {
 
         private final SearchScript searchScript;
 
-        private final ScriptService.ScriptType scriptType;
-
         public ScriptFilter(String scriptLang, String script, ScriptService.ScriptType scriptType, Map<String, Object> params, ScriptService scriptService, SearchLookup searchLookup) {
             this.script = script;
             this.params = params;
-            this.scriptType = scriptType;
             this.searchScript = scriptService.search(searchLookup, scriptLang, script, scriptType, newHashMap(params));
         }
 

src/main/java/org/elasticsearch/index/query/TemplateQueryBuilder.java

@@ -21,7 +21,6 @@
 import org.elasticsearch.ElasticsearchIllegalArgumentException;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.script.ScriptService;
-import org.elasticsearch.search.aggregations.support.ValuesSource;
 
 import java.io.IOException;
 import java.util.Map;

src/main/java/org/elasticsearch/index/query/TemplateQueryParser.java

@@ -19,17 +19,15 @@
 package org.elasticsearch.index.query;
 
 import org.apache.lucene.search.Query;
-import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.inject.Inject;
-import org.elasticsearch.common.logging.ESLogger;
-import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.script.ExecutableScript;
 import org.elasticsearch.script.ScriptService;
+import org.elasticsearch.script.mustache.MustacheScriptEngineService;
 
 import java.io.IOException;
 import java.util.HashMap;
@@ -52,9 +50,9 @@ public class TemplateQueryParser implements QueryParser {
 
     private final static Map<String,ScriptService.ScriptType> parametersToTypes = new HashMap<>();
     static {
-        parametersToTypes.put("query",ScriptService.ScriptType.INLINE);
-        parametersToTypes.put("file",ScriptService.ScriptType.FILE);
-        parametersToTypes.put("id",ScriptService.ScriptType.INDEXED);
+        parametersToTypes.put("query", ScriptService.ScriptType.INLINE);
+        parametersToTypes.put("file", ScriptService.ScriptType.FILE);
+        parametersToTypes.put("id", ScriptService.ScriptType.INDEXED);
     }
 
     @Inject
@@ -78,15 +76,14 @@ public String[] names() {
     public Query parse(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         TemplateContext templateContext = parse(parser, PARAMS, parametersToTypes);
-        ExecutableScript executable = this.scriptService.executable("mustache", templateContext.template(), templateContext.scriptType(), templateContext.params());
+        ExecutableScript executable = this.scriptService.executable(MustacheScriptEngineService.NAME, templateContext.template(), templateContext.scriptType(), templateContext.params());
 
         BytesReference querySource = (BytesReference) executable.run();
 
         try (XContentParser qSourceParser = XContentFactory.xContent(querySource).createParser(querySource)) {
             final QueryParseContext context = new QueryParseContext(parseContext.index(), parseContext.indexQueryParserService());
             context.reset(qSourceParser);
-            Query result = context.parseInnerQuery();
-            return result;
+            return context.parseInnerQuery();
         }
     }
 

src/main/java/org/elasticsearch/index/query/functionscore/script/ScriptScoreFunctionParser.java

@@ -56,7 +56,6 @@ public String[] getNames() {
     public ScoreFunction parse(QueryParseContext parseContext, XContentParser parser) throws IOException, QueryParsingException {
         ScriptParameterParser scriptParameterParser = new ScriptParameterParser();
         String script = null;
-        String scriptLang = null;
         Map<String, Object> vars = null;
         ScriptService.ScriptType scriptType = null;
         String currentFieldName = null;
@@ -82,15 +81,13 @@ public ScoreFunction parse(QueryParseContext parseContext, XContentParser parser
             script = scriptValue.script();
             scriptType = scriptValue.scriptType();
         }
-        scriptLang = scriptParameterParser.lang();
-
         if (script == null) {
             throw new QueryParsingException(parseContext.index(), NAMES[0] + " requires 'script' field");
         }
 
         SearchScript searchScript;
         try {
-            searchScript = parseContext.scriptService().search(parseContext.lookup(), scriptLang, script, scriptType, vars);
+            searchScript = parseContext.scriptService().search(parseContext.lookup(), scriptParameterParser.lang(), script, scriptType, vars);
             return new ScriptScoreFunction(script, vars, searchScript);
         } catch (Exception e) {
             throw new QueryParsingException(parseContext.index(), NAMES[0] + " the script could not be loaded", e);

src/main/java/org/elasticsearch/rest/action/template/RestDeleteSearchTemplateAction.java

@@ -24,6 +24,7 @@
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.action.script.RestDeleteIndexedScriptAction;
+import org.elasticsearch.script.mustache.MustacheScriptEngineService;
 
 import static org.elasticsearch.rest.RestRequest.Method.DELETE;
 
@@ -37,6 +38,6 @@ public RestDeleteSearchTemplateAction(Settings settings, RestController controll
 
     @Override
     protected String getScriptLang(RestRequest request) {
-        return "mustache";
+        return MustacheScriptEngineService.NAME;
     }
 }

src/main/java/org/elasticsearch/rest/action/template/RestGetSearchTemplateAction.java

@@ -24,6 +24,7 @@
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.action.script.RestGetIndexedScriptAction;
+import org.elasticsearch.script.mustache.MustacheScriptEngineService;
 
 import static org.elasticsearch.rest.RestRequest.Method.GET;
 
@@ -40,7 +41,7 @@ public RestGetSearchTemplateAction(Settings settings, RestController controller,
 
     @Override
     protected String getScriptLang(RestRequest request) {
-        return "mustache";
+        return MustacheScriptEngineService.NAME;
     }
 
     @Override

src/main/java/org/elasticsearch/rest/action/template/RestPutSearchTemplateAction.java

@@ -23,6 +23,7 @@
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.rest.*;
 import org.elasticsearch.rest.action.script.RestPutIndexedScriptAction;
+import org.elasticsearch.script.mustache.MustacheScriptEngineService;
 
 import static org.elasticsearch.rest.RestRequest.Method.POST;
 import static org.elasticsearch.rest.RestRequest.Method.PUT;
@@ -58,6 +59,6 @@ public void handleRequest(RestRequest request, RestChannel channel, final Client
 
     @Override
     protected String getScriptLang(RestRequest request) {
-        return "mustache";
+        return MustacheScriptEngineService.NAME;
     }
 }

src/main/java/org/elasticsearch/script/NativeScriptEngineService.java

@@ -34,6 +34,8 @@
  */
 public class NativeScriptEngineService extends AbstractComponent implements ScriptEngineService {
 
+    public static final String NAME = "native";
+
     private final ImmutableMap<String, NativeScriptFactory> scripts;
 
     @Inject
@@ -44,7 +46,7 @@ public NativeScriptEngineService(Settings settings, Map<String, NativeScriptFact
 
     @Override
     public String[] types() {
-        return new String[]{"native"};
+        return new String[]{NAME};
     }
 
     @Override