/*
* Licensed 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 com.facebook.presto.server;
import com.facebook.presto.spi.Plugin;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import org.objectweb.asm.ClassReader;
import org.sonatype.aether.artifact.Artifact;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.file.FileVisitResult;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.List;
import java.util.Set;
import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static com.google.common.io.ByteStreams.toByteArray;
import static java.nio.charset.StandardCharsets.UTF_8;
import static java.nio.file.Files.createDirectories;
import static java.nio.file.Files.walkFileTree;
// This is a hack for development and does not support nested classes.
final class PluginDiscovery
{
private static final String CLASS_FILE_SUFFIX = ".class";
private static final String SERVICES_FILE = "META-INF/services/" + Plugin.class.getName();
private PluginDiscovery() {}
public static Set<String> discoverPlugins(Artifact artifact, ClassLoader classLoader)
throws IOException
{
if (!artifact.getExtension().equals("presto-plugin")) {
throw new RuntimeException("Unexpected extension for main artifact: " + artifact);
}
File file = artifact.getFile();
if (!file.getPath().endsWith("/target/classes")) {
throw new RuntimeException("Unexpected file for main artifact: " + file);
}
if (!file.isDirectory()) {
throw new RuntimeException("Main artifact file is not a directory: " + file);
}
if (new File(file, SERVICES_FILE).exists()) {
return ImmutableSet.of();
}
return listClasses(file.toPath()).stream()
.filter(name -> classInterfaces(name, classLoader).contains(Plugin.class.getName()))
.collect(toImmutableSet());
}
public static void writePluginServices(Iterable<String> plugins, File root)
throws IOException
{
Path path = root.toPath().resolve(SERVICES_FILE);
createDirectories(path.getParent());
try (Writer out = new OutputStreamWriter(new FileOutputStream(path.toFile()), UTF_8)) {
for (String plugin : plugins) {
out.write(plugin + "\n");
}
}
}
private static List<String> listClasses(Path base)
throws IOException
{
ImmutableList.Builder<String> list = ImmutableList.builder();
walkFileTree(base, new SimpleFileVisitor<Path>()
{
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attributes)
throws IOException
{
if (file.getFileName().toString().endsWith(CLASS_FILE_SUFFIX)) {
String name = file.subpath(base.getNameCount(), file.getNameCount()).toString();
list.add(javaName(name.substring(0, name.length() - CLASS_FILE_SUFFIX.length())));
}
return FileVisitResult.CONTINUE;
}
});
return list.build();
}
private static List<String> classInterfaces(String name, ClassLoader classLoader)
{
ImmutableList.Builder<String> list = ImmutableList.builder();
ClassReader reader = readClass(name, classLoader);
for (String binaryName : reader.getInterfaces()) {
list.add(javaName(binaryName));
}
if (reader.getSuperName() != null) {
list.addAll(classInterfaces(javaName(reader.getSuperName()), classLoader));
}
return list.build();
}
private static ClassReader readClass(String name, ClassLoader classLoader)
{
try (InputStream in = classLoader.getResourceAsStream(binaryName(name) + CLASS_FILE_SUFFIX)) {
if (in == null) {
throw new RuntimeException("Failed to read class: " + name);
}
return new ClassReader(toByteArray(in));
}
catch (IOException e) {
throw Throwables.propagate(e);
}
}
private static String binaryName(String javaName)
{
return javaName.replace('.', '/');
}
private static String javaName(String binaryName)
{
return binaryName.replace('/', '.');
}
}