Cache templates

This commit improves massively class loading performance by caching all
templates used by the generator. GroovyTemplate is now a bean rather than
a private utility.

Templates are cached by default and the cache is disabled automatically
if Devtools is in use (via a check of spring.groovy.template.cache).

Closes gh-288

initializr-generator/src/main/groovy/io/spring/initializr/generator/CommandLineHelpGenerator.groovy

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,10 +18,9 @@ package io.spring.initializr.generator
 
 import io.spring.initializr.metadata.InitializrMetadata
 import io.spring.initializr.metadata.Type
+import io.spring.initializr.util.GroovyTemplate
 import io.spring.initializr.util.VersionRange
 
-import static io.spring.initializr.util.GroovyTemplate.template
-
 /**
  * Generate help pages for command-line clients.
  *
@@ -39,6 +38,12 @@ class CommandLineHelpGenerator {
  =========|_|==============|___/=/_/_/_/
  '''
 
+ 	private final GroovyTemplate template
+
+	CommandLineHelpGenerator(GroovyTemplate template) {
+		this.template = template
+	}
+
 	/**
 	 * Generate the capabilities of the service as a generic plain text
 	 * document. Used when no particular agent was detected.
@@ -46,7 +51,7 @@ class CommandLineHelpGenerator {
 	String generateGenericCapabilities(InitializrMetadata metadata, String serviceUrl) {
 		def model = initializeCommandLineModel(metadata, serviceUrl)
 		model['hasExamples'] = false
-		template 'cli-capabilities.txt', model
+		template.process 'cli-capabilities.txt', model
 	}
 
 	/**
@@ -55,9 +60,9 @@ class CommandLineHelpGenerator {
 	 */
 	String generateCurlCapabilities(InitializrMetadata metadata, String serviceUrl) {
 		def model = initializeCommandLineModel(metadata, serviceUrl)
-		model['examples'] = template 'curl-examples.txt', model
+		model['examples'] = template.process 'curl-examples.txt', model
 		model['hasExamples'] = true
-		template 'cli-capabilities.txt', model
+		template.process 'cli-capabilities.txt', model
 	}
 
 	/**
@@ -66,9 +71,9 @@ class CommandLineHelpGenerator {
 	 */
 	String generateHttpieCapabilities(InitializrMetadata metadata, String serviceUrl) {
 		def model = initializeCommandLineModel(metadata, serviceUrl)
-		model['examples'] = template 'httpie-examples.txt', model
+		model['examples'] = template.process 'httpie-examples.txt', model
 		model['hasExamples'] = true
-		template 'cli-capabilities.txt', model
+		template.process 'cli-capabilities.txt', model
 	}
 
 	/**
@@ -78,7 +83,7 @@ class CommandLineHelpGenerator {
 	String generateSpringBootCliCapabilities(InitializrMetadata metadata, String serviceUrl) {
 		def model = initializeSpringBootCliModel(metadata, serviceUrl)
 		model['hasExamples'] = false
-		template('boot-cli-capabilities.txt', model)
+		template.process('boot-cli-capabilities.txt', model)
 	}
 
 	protected Map initializeCommandLineModel(InitializrMetadata metadata, serviceUrl) {

initializr-generator/src/main/groovy/io/spring/initializr/generator/ProjectGenerator.groovy

@@ -20,6 +20,7 @@ import groovy.util.logging.Slf4j
 import io.spring.initializr.InitializrException
 import io.spring.initializr.metadata.Dependency
 import io.spring.initializr.metadata.InitializrMetadataProvider
+import io.spring.initializr.util.GroovyTemplate
 import io.spring.initializr.util.Version
 
 import org.springframework.beans.factory.annotation.Autowired
@@ -28,7 +29,6 @@ import org.springframework.context.ApplicationEventPublisher
 import org.springframework.util.Assert
 
 import static io.spring.initializr.metadata.InitializrConfiguration.Env.Maven.ParentPom
-import static io.spring.initializr.util.GroovyTemplate.template
 
 /**
  * Generate a project based on the configured metadata.
@@ -58,6 +58,9 @@ class ProjectGenerator {
 	@Autowired
 	ProjectRequestResolver requestResolver
 
+	@Autowired
+	GroovyTemplate groovyTemplate = new GroovyTemplate()
+
 	@Autowired
 	ProjectResourceLocator projectResourceLocator = new ProjectResourceLocator()
 
@@ -321,12 +324,12 @@ class ProjectGenerator {
 	}
 
 	private byte[] doGenerateMavenPom(Map model) {
-		template 'starter-pom.xml', model
+		groovyTemplate.process 'starter-pom.xml', model
 	}
 
 
 	private byte[] doGenerateGradleBuild(Map model) {
-		template 'starter-build.gradle', model
+		groovyTemplate.process 'starter-build.gradle', model
 	}
 
 	private void writeGradleWrapper(File dir) {
@@ -384,7 +387,7 @@ class ProjectGenerator {
 
 	def write(File target, String templateName, def model) {
 		def tmpl = templateName.endsWith('.groovy') ? templateName + '.tmpl' : templateName
-		def body = template tmpl, model
+		def body = groovyTemplate.process tmpl, model
 		target.write(body)
 	}
 

initializr-generator/src/main/groovy/io/spring/initializr/util/GroovyTemplate.groovy

@@ -16,36 +16,52 @@
 
 package io.spring.initializr.util
 
+import java.util.concurrent.ConcurrentMap
+
 import groovy.text.GStringTemplateEngine
 import groovy.text.Template
 import groovy.text.TemplateEngine
 import org.codehaus.groovy.control.CompilationFailedException
 
+import org.springframework.util.ConcurrentReferenceHashMap
+
 /**
  * @author Dave Syer
  * @since 1.0
  */
 class GroovyTemplate {
 
-	// This is a copy/paste from GroovyTemplate in spring-boot-cli. We should migrate
-	// to Spring's native support available in 4.1
+	boolean cache = true
 
-	static String template(String name, Map<String, ?> model) throws IOException,
-			CompilationFailedException, ClassNotFoundException {
-		template(new GStringTemplateEngine(), name, model)
+	private final TemplateEngine engine
+	private final ConcurrentMap<String, Template> templateCaches = new ConcurrentReferenceHashMap<>()
+
+	GroovyTemplate(TemplateEngine engine) {
+		this.engine = engine
 	}
 
-	static String template(TemplateEngine engine, String name, Map<String, ?> model)
+	GroovyTemplate() {
+		this(new GStringTemplateEngine())
+	}
+
+	String process(String name, Map<String, ?> model)
 			throws IOException, CompilationFailedException, ClassNotFoundException {
-		def writable = getTemplate(engine, name).make(model)
+		def template = getTemplate(name)
+		def writable = template.make(model)
 		def result = new StringWriter()
 		writable.writeTo(result)
 		result.toString()
 	}
 
-	static Template getTemplate(TemplateEngine engine, String name)
+	Template getTemplate(String name)
 			throws CompilationFailedException, ClassNotFoundException, IOException {
+		if (cache) {
+			return this.templateCaches.computeIfAbsent(name, { n -> loadTemplate(n) })
+		}
+		return loadTemplate(name)
+	}
 
+	protected Template loadTemplate(String name) {
 		def file = new File("templates", name)
 		if (file.exists()) {
 			return engine.createTemplate(file)
@@ -59,4 +75,5 @@ class GroovyTemplate {
 
 		return engine.createTemplate(name)
 	}
+
 }

initializr-generator/src/test/groovy/io/spring/initializr/generator/CommandLineHelpGeneratorTests.groovy

@@ -19,6 +19,7 @@ package io.spring.initializr.generator
 import io.spring.initializr.metadata.Dependency
 import io.spring.initializr.metadata.Type
 import io.spring.initializr.test.metadata.InitializrMetadataTestBuilder
+import io.spring.initializr.util.GroovyTemplate
 import org.junit.Test
 
 import static org.hamcrest.CoreMatchers.containsString
@@ -30,7 +31,7 @@ import static org.junit.Assert.assertThat
  */
 class CommandLineHelpGeneratorTests {
 
-	private CommandLineHelpGenerator generator = new CommandLineHelpGenerator()
+	private CommandLineHelpGenerator generator = new CommandLineHelpGenerator(new GroovyTemplate())
 
 	@Test
 	void generateGenericCapabilities() {