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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.config.buildergen;
import com.yahoo.config.ConfigInstance;
import javax.tools.*;
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;
import java.util.Locale;
/**
* Represents a compiler that waits performing the compilation until the requested builder is requested from the
* {@link CompiledBuilder}.
*
* @author Ulf Lilleengen
*/
public class LazyConfigCompiler implements ConfigCompiler {
private final File outputDirectory;
private final ClassLoader classLoader;
private final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
public LazyConfigCompiler(File outputDirectory) {
this.outputDirectory = outputDirectory;
try {
this.classLoader = new URLClassLoader(new URL[]{outputDirectory.toURI().toURL()});
} catch (MalformedURLException e) {
throw new IllegalArgumentException("Unable to create class loader for directory '" + outputDirectory.getAbsolutePath() + "'", e);
}
}
@Override
public CompiledBuilder compile(ConfigDefinitionClass defClass) {
Iterable<? extends JavaFileObject> compilationUnits = Arrays.asList(new StringSourceObject(defClass.getName(), defClass.getDefinition()));
DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<>();
StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, Locale.ENGLISH, null);
Iterable<String> options = Arrays.asList("-d", outputDirectory.getAbsolutePath());
JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, diagnostics, options, null, compilationUnits);
return new LazyCompiledBuilder(classLoader, defClass.getName(), new CompilationTask(task, diagnostics));
}
/**
* Lazy implementation of compiled builder that defers compilation until class is requested.
*/
private static class LazyCompiledBuilder implements CompiledBuilder {
private final ClassLoader classLoader;
private final String classUrl;
private final CompilationTask compilationTask;
private LazyCompiledBuilder(ClassLoader classLoader, String classUrl, CompilationTask compilationTask) {
this.classLoader = classLoader;
this.classUrl = classUrl;
this.compilationTask = compilationTask;
}
@Override
public <BUILDER extends ConfigInstance.Builder> BUILDER newInstance() {
compileBuilder();
String builderClassUrl = classUrl + "$Builder";
return loadBuilder(builderClassUrl);
}
private void compileBuilder() {
try {
compilationTask.call();
} catch (IllegalArgumentException e) {
throw new IllegalArgumentException("Error compiling '" + classUrl + "'", e);
}
}
@SuppressWarnings("unchecked")
private <BUILDER extends ConfigInstance.Builder> BUILDER loadBuilder(String builderClassUrl) {
try {
Class<BUILDER> clazz = (Class<BUILDER>) classLoader.loadClass(builderClassUrl);
return clazz.getDeclaredConstructor().newInstance();
} catch (ReflectiveOperationException e) {
throw new RuntimeException("Error creating new instance of '" + builderClassUrl + "'", e);
}
}
}
}
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