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/*
* 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.script.mustache;
import com.github.mustachejava.Mustache;
import com.github.mustachejava.MustacheFactory;
import org.apache.logging.log4j.message.ParameterizedMessage;
import org.apache.logging.log4j.util.Supplier;
import org.elasticsearch.SpecialPermission;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.io.FastStringReader;
import org.elasticsearch.common.io.UTF8StreamWriter;
import org.elasticsearch.common.io.stream.BytesStreamOutput;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.script.CompiledScript;
import org.elasticsearch.script.ExecutableScript;
import org.elasticsearch.script.GeneralScriptException;
import org.elasticsearch.script.ScriptEngineService;
import org.elasticsearch.script.SearchScript;
import org.elasticsearch.search.lookup.SearchLookup;
import java.io.Reader;
import java.lang.ref.SoftReference;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.Map;
import static org.elasticsearch.script.mustache.CustomMustacheFactory.CONTENT_TYPE_PARAM;
/**
* Main entry point handling template registration, compilation and
* execution.
*
* Template handling is based on Mustache. Template handling is a two step
* process: First compile the string representing the template, the resulting
* {@link Mustache} object can then be re-used for subsequent executions.
*/
public final class MustacheScriptEngineService extends AbstractComponent implements ScriptEngineService {
public static final String NAME = "mustache";
/** Thread local UTF8StreamWriter to store template execution results in, thread local to save object creation.*/
private static ThreadLocal<SoftReference<UTF8StreamWriter>> utf8StreamWriter = new ThreadLocal<>();
/** If exists, reset and return, otherwise create, reset and return a writer.*/
private static UTF8StreamWriter utf8StreamWriter() {
SoftReference<UTF8StreamWriter> ref = utf8StreamWriter.get();
UTF8StreamWriter writer = (ref == null) ? null : ref.get();
if (writer == null) {
writer = new UTF8StreamWriter(1024 * 4);
utf8StreamWriter.set(new SoftReference<>(writer));
}
writer.reset();
return writer;
}
/**
* @param settings automatically wired by Guice.
* */
public MustacheScriptEngineService(Settings settings) {
super(settings);
}
/**
* Compile a template string to (in this case) a Mustache object than can
* later be re-used for execution to fill in missing parameter values.
*
* @param templateSource a string representing the template to compile.
* @return a compiled template object for later execution.
* */
@Override
public Object compile(String templateName, String templateSource, Map<String, String> params) {
final MustacheFactory factory = createMustacheFactory(params);
Reader reader = new FastStringReader(templateSource);
return factory.compile(reader, "query-template");
}
private CustomMustacheFactory createMustacheFactory(Map<String, String> params) {
if (params == null || params.isEmpty() || params.containsKey(CONTENT_TYPE_PARAM) == false) {
return new CustomMustacheFactory();
}
return new CustomMustacheFactory(params.get(CONTENT_TYPE_PARAM));
}
@Override
public String getType() {
return NAME;
}
@Override
public String getExtension() {
return NAME;
}
@Override
public ExecutableScript executable(CompiledScript compiledScript,
@Nullable Map<String, Object> vars) {
return new MustacheExecutableScript(compiledScript, vars);
}
@Override
public SearchScript search(CompiledScript compiledScript, SearchLookup lookup,
@Nullable Map<String, Object> vars) {
throw new UnsupportedOperationException();
}
@Override
public void close() {
// Nothing to do here
}
// permission checked before doing crazy reflection
static final SpecialPermission SPECIAL_PERMISSION = new SpecialPermission();
/**
* Used at query execution time by script service in order to execute a query template.
* */
private class MustacheExecutableScript implements ExecutableScript {
/** Compiled template object wrapper. */
private CompiledScript template;
/** Parameters to fill above object with. */
private Map<String, Object> vars;
/**
* @param template the compiled template object wrapper
* @param vars the parameters to fill above object with
**/
public MustacheExecutableScript(CompiledScript template, Map<String, Object> vars) {
this.template = template;
this.vars = vars == null ? Collections.<String, Object>emptyMap() : vars;
}
@Override
public void setNextVar(String name, Object value) {
this.vars.put(name, value);
}
@Override
public Object run() {
final BytesStreamOutput result = new BytesStreamOutput();
try (UTF8StreamWriter writer = utf8StreamWriter().setOutput(result)) {
// crazy reflection here
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(SPECIAL_PERMISSION);
}
AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
((Mustache) template.compiled()).execute(writer, vars);
return null;
});
} catch (Exception e) {
logger.error((Supplier<?>) () -> new ParameterizedMessage("Error running {}", template), e);
throw new GeneralScriptException("Error running " + template, e);
}
return result.bytes();
}
}
@Override
public boolean isInlineScriptEnabled() {
return true;
}
}
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