/*
* Copyright (c) 2010 - 2011, Jan Stender, Bjoern Kolbeck, Mikael Hoegqvist,
* Felix Hupfeld, Felix Langner, Zuse Institute Berlin
*
* Licensed under the BSD License, see LICENSE file for details.
*
*/
package de.mxro.thrd.babudb05.plugin;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.jar.JarEntry;
import java.util.jar.JarInputStream;
import de.mxro.thrd.babudb05.api.dev.BabuDBInternal;
import de.mxro.thrd.babudb05.api.dev.plugin.PluginMain;
import de.mxro.thrd.babudb05.config.PluginConfig;
import de.mxro.thrd.xstreemfs.foundation.logging.Logging;
import static de.mxro.thrd.babudb05.BabuDBFactory.*;
/**
* {@link ClassLoader} for accessing optional plugins for BabuDB.
* Plugins may access BabuDB via BabuDB Main.start(BabuDBInternal babuDB).
*
* @author flangner
* @date 11/01/2010
*/
public final class PluginLoader extends ClassLoader {
private final Map<String, byte[]> clazzes = new HashMap<String, byte[]>();
private BabuDBInternal babuDB;
/**
* Creates a BabuDB JAR class loader for the plugins defined within the
* configuration file. It will automatically attempt to load its JAR
* for the given data version.
*
* @param babuDBImpl
*
* @throws IOException if an I/O error occurred
*/
private PluginLoader(BabuDBInternal dbs) throws IOException {
super();
this.babuDB = dbs;
// start all plugins registered
for (String configPath : dbs.getConfig().getPlugins()) {
String main = null;
PluginConfig c = new PluginConfig(configPath);
String pluginPath = c.getPluginLibraryPath();
try {
// load all classes from the plugin JARs
main = loadJar(pluginPath, "Main");
if (main == null) {
throw new Exception("main class (extending PluginMain) not found!");
}
// load the plugins dependencies
PluginMain m = (PluginMain) loadClass(main).newInstance();
for (String depPath : m.getDependencies(configPath)) {
Logging.logMessage(Logging.LEVEL_INFO, this, "Loading plugin dependency %s.",
depPath);
loadJar(depPath);
}
// start the plugin
babuDB = m.execute(babuDB, configPath);
} catch (Exception e) {
if (e.getMessage() == null) Logging.logError(Logging.LEVEL_WARN, this, e);
throw new IOException("Plugin at '" + pluginPath + "' for version " + BABUDB_VERSION
+ ((configPath != null) ? " with config at path " + configPath : "")
+ " could not be initialized, because " + e.getMessage()
+ "!", e.getCause());
}
}
}
/**
* Loads all classes from the jar found at path to be available to the ClassLoader.
*
* @param path
* @throws IOException
* @throws FileNotFoundException
*/
private final void loadJar(String path) throws FileNotFoundException, IOException {
loadJar(path, null);
}
/**
* Loads all classes from the jar found at path to be available to the ClassLoader.
*
* @param path
* @param classToSearchFor
* @throws IOException
* @throws FileNotFoundException
*/
private final String loadJar(String path, String classToSearchFor) throws FileNotFoundException,
IOException {
JarInputStream jis = new JarInputStream(new FileInputStream(path));
JarEntry next = null;
String main = null;
while ((next = jis.getNextJarEntry()) != null) {
if (!next.getName().endsWith(".class")) {
continue;
}
byte[] buf = new byte[4096];
ByteArrayOutputStream out = new ByteArrayOutputStream();
int len = -1;
while ((len = jis.read(buf)) > 0) {
out.write(buf, 0, len);
}
String className = next.getName().substring(0, next.getName().length() -
".class".length()).replace('/', '.');
if (classToSearchFor != null && className.endsWith(classToSearchFor)) {
assert (main == null);
main = className;
}
if (!clazzes.containsKey(className)) {
clazzes.put(className, out.toByteArray());
} else {
Logging.logMessage(Logging.LEVEL_DEBUG, this, "Did not load %s from %s, " +
"because it already exists.", className, path);
}
out.close();
}
jis.close();
return main;
}
/*
* (non-Javadoc)
* @see java.lang.ClassLoader#loadClass(java.lang.String, boolean)
*/
@Override
public Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
Class<?> clazz = findLoadedClass(name);
if (clazz == null) {
byte[] classBytes = clazzes.get(name);
if (classBytes != null) {
clazz = defineClass(name, classBytes, 0, classBytes.length);
} else {
clazz = getParent().loadClass(name);
}
}
if (resolve) {
resolveClass(clazz);
}
return clazz;
}
/**
* This methods loads all available plugins and allows the plugins to overload the BabuDB API.
*
* @param babuDB
* @return the overloaded BabuDB.
*
* @throws IOException if a plugin could not be loaded.
*/
public final static BabuDBInternal init(BabuDBInternal babuDB) throws IOException {
PluginLoader loader = new PluginLoader(babuDB);
return loader.babuDB;
}
}