Scripting: Convert CompiledTemplate to a ScriptContext (#25032)

This commit creates TemplateScript and associated classes so that
templates no longer need a special ScriptService.compileTemplate method.
The execute() method is equivalent to the old run() method.

relates #20426

3 files changed, 22 insertions, 31 deletions

diff --git a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/MustacheScriptEngine.java b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/MustacheScriptEngine.java
index 3363db47b4..65e23ef87a 100644
--- a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/MustacheScriptEngine.java
+++ b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/MustacheScriptEngine.java
@@ -27,17 +27,16 @@ import org.apache.logging.log4j.util.Supplier;
 import org.elasticsearch.SpecialPermission;
 import org.elasticsearch.common.io.FastStringReader;
 import org.elasticsearch.common.logging.ESLoggerFactory;
-import org.elasticsearch.script.ExecutableScript;
 import org.elasticsearch.script.GeneralScriptException;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.script.ScriptEngine;
+import org.elasticsearch.script.TemplateScript;
 
 import java.io.Reader;
 import java.io.StringWriter;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
-import java.util.Collections;
 import java.util.Map;
 
 /**
@@ -61,22 +60,22 @@ public final class MustacheScriptEngine implements ScriptEngine {
      * @return a compiled template object for later execution.
      * */
     @Override
-    public <T> T compile(String templateName, String templateSource, ScriptContext<T> context, Map<String, String> params) {
-        if (context.instanceClazz.equals(ExecutableScript.class) == false) {
+    public <T> T compile(String templateName, String templateSource, ScriptContext<T> context, Map<String, String> options) {
+        if (context.instanceClazz.equals(TemplateScript.class) == false) {
             throw new IllegalArgumentException("mustache engine does not know how to handle context [" + context.name + "]");
         }
-        final MustacheFactory factory = createMustacheFactory(params);
+        final MustacheFactory factory = createMustacheFactory(options);
         Reader reader = new FastStringReader(templateSource);
         Mustache template = factory.compile(reader, "query-template");
-        ExecutableScript.Factory compiled = p -> new MustacheExecutableScript(template, p);
+        TemplateScript.Factory compiled = params -> new MustacheExecutableScript(template, params);
         return context.factoryClazz.cast(compiled);
     }
 
-    private CustomMustacheFactory createMustacheFactory(Map<String, String> params) {
-        if (params == null || params.isEmpty() || params.containsKey(Script.CONTENT_TYPE_OPTION) == false) {
+    private CustomMustacheFactory createMustacheFactory(Map<String, String> options) {
+        if (options == null || options.isEmpty() || options.containsKey(Script.CONTENT_TYPE_OPTION) == false) {
             return new CustomMustacheFactory();
         }
-        return new CustomMustacheFactory(params.get(Script.CONTENT_TYPE_OPTION));
+        return new CustomMustacheFactory(options.get(Script.CONTENT_TYPE_OPTION));
     }
 
     @Override
@@ -87,34 +86,28 @@ public final class MustacheScriptEngine implements ScriptEngine {
     /**
      * Used at query execution time by script service in order to execute a query template.
      * */
-    private class MustacheExecutableScript implements ExecutableScript {
+    private class MustacheExecutableScript implements TemplateScript {
         /** Factory template. */
         private Mustache template;
-        /** Parameters to fill above object with. */
-        private Map<String, Object> vars;
+
+        private Map<String, Object> params;
 
         /**
          * @param template the compiled template object wrapper
-         * @param vars the parameters to fill above object with
          **/
-        MustacheExecutableScript(Mustache template, Map<String, Object> vars) {
+        MustacheExecutableScript(Mustache template, Map<String, Object> params) {
             this.template = template;
-            this.vars = vars == null ? Collections.emptyMap() : vars;
-        }
-
-        @Override
-        public void setNextVar(String name, Object value) {
-            this.vars.put(name, value);
+            this.params = params;
         }
 
         @Override
-        public Object run() {
+        public String execute() {
             final StringWriter writer = new StringWriter();
             try {
                 // crazy reflection here
                 SpecialPermission.check();
                 AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
-                    template.execute(writer, vars);
+                    template.execute(writer, params);
                     return null;
                 });
             } catch (Exception e) {
diff --git a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestPutSearchTemplateAction.java b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestPutSearchTemplateAction.java
index ecee7f67c8..751e58aeeb 100644
--- a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestPutSearchTemplateAction.java
+++ b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestPutSearchTemplateAction.java
@@ -18,6 +18,8 @@
  */
 package org.elasticsearch.script.mustache;
 
+import java.io.IOException;
+
 import org.elasticsearch.action.admin.cluster.storedscripts.PutStoredScriptRequest;
 import org.elasticsearch.client.node.NodeClient;
 import org.elasticsearch.common.bytes.BytesReference;
@@ -26,10 +28,8 @@ import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.action.AcknowledgedRestListener;
-import org.elasticsearch.script.ExecutableScript;
 import org.elasticsearch.script.Script;
-
-import java.io.IOException;
+import org.elasticsearch.script.TemplateScript;
 
 import static org.elasticsearch.rest.RestRequest.Method.POST;
 import static org.elasticsearch.rest.RestRequest.Method.PUT;
@@ -53,7 +53,7 @@ public class RestPutSearchTemplateAction extends BaseRestHandler {
         String id = request.param("id");
         BytesReference content = request.content();
 
-        PutStoredScriptRequest put = new PutStoredScriptRequest(id, Script.DEFAULT_TEMPLATE_LANG, ExecutableScript.CONTEXT.name,
+        PutStoredScriptRequest put = new PutStoredScriptRequest(id, Script.DEFAULT_TEMPLATE_LANG, TemplateScript.CONTEXT.name,
             content, request.getXContentType());
         return channel -> client.admin().cluster().putStoredScript(put, new AcknowledgedRestListener<>(channel));
     }
diff --git a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java
index faf543e2a0..d1e6377b69 100644
--- a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java
+++ b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java
@@ -37,16 +37,14 @@ import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.script.ExecutableScript;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptService;
+import org.elasticsearch.script.TemplateScript;
 import org.elasticsearch.search.builder.SearchSourceBuilder;
-import org.elasticsearch.template.CompiledTemplate;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 
 import java.io.IOException;
 import java.util.Collections;
 
-import static org.elasticsearch.script.ExecutableScript.CONTEXT;
-
 public class TransportSearchTemplateAction extends HandledTransportAction<SearchTemplateRequest, SearchTemplateResponse> {
 
     private static final String TEMPLATE_LANG = MustacheScriptEngine.NAME;
@@ -101,8 +99,8 @@ public class TransportSearchTemplateAction extends HandledTransportAction<Search
                                  NamedXContentRegistry xContentRegistry) throws IOException {
         Script script = new Script(searchTemplateRequest.getScriptType(), TEMPLATE_LANG, searchTemplateRequest.getScript(),
                 searchTemplateRequest.getScriptParams() == null ? Collections.emptyMap() : searchTemplateRequest.getScriptParams());
-        CompiledTemplate compiledScript = scriptService.compileTemplate(script, ExecutableScript.CONTEXT);
-        String source = compiledScript.run(script.getParams());
+        TemplateScript compiledScript = scriptService.compile(script, TemplateScript.CONTEXT).newInstance(script.getParams());
+        String source = compiledScript.execute();
         response.setSource(new BytesArray(source));
 
         SearchRequest searchRequest = searchTemplateRequest.getRequest();