javax.management.loading.MLet Maven / Gradle / Ivy
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/*
* Copyright (C) The MX4J Contributors.
* All rights reserved.
*
* This software is distributed under the terms of the MX4J License version 1.0.
* See the terms of the MX4J License in the documentation provided with this software.
*/
package javax.management.loading;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.Externalizable;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLStreamHandlerFactory;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import javax.management.MBeanRegistration;
import javax.management.MBeanServer;
import javax.management.ObjectInstance;
import javax.management.ObjectName;
import javax.management.ServiceNotFoundException;
import mx4j.loading.ClassLoaderObjectInputStream;
import mx4j.loading.MLetParseException;
import mx4j.loading.MLetParser;
import mx4j.loading.MLetTag;
import mx4j.log.Log;
import mx4j.log.Logger;
/**
* @version $Revision: 1.27 $
*/
public class MLet extends URLClassLoader implements MLetMBean, MBeanRegistration, Externalizable
{
private MBeanServer server;
private ObjectName objectName;
private boolean delegateToCLR;
private ThreadLocal loadingOnlyLocally = new ThreadLocal();
private ThreadLocal loadingWithRepository = new ThreadLocal();
private String libraryDir;
public MLet()
{
this(new URL[0]);
}
public MLet(URL[] urls)
{
this(urls, true);
}
public MLet(URL[] urls, boolean delegateToCLR)
{
super(urls);
setDelegateToCLR(delegateToCLR);
loadingWithRepository.set(Boolean.FALSE);
loadingOnlyLocally.set(Boolean.FALSE);
}
public MLet(URL[] urls, ClassLoader parent)
{
this(urls, parent, true);
}
public MLet(URL[] urls, ClassLoader parent, boolean delegateToCLR)
{
super(urls, parent);
setDelegateToCLR(delegateToCLR);
loadingWithRepository.set(Boolean.FALSE);
loadingOnlyLocally.set(Boolean.FALSE);
}
public MLet(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory)
{
this(urls, parent, factory, true);
}
public MLet(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory, boolean delegateToCLR)
{
super(urls, parent, factory);
this.setDelegateToCLR(delegateToCLR);
loadingWithRepository.set(Boolean.FALSE);
loadingOnlyLocally.set(Boolean.FALSE);
}
public ObjectName preRegister(MBeanServer server, ObjectName name) throws Exception
{
this.server = server;
objectName = name == null ? new ObjectName(this.server.getDefaultDomain(), "type", "MLet") : name;
Logger logger = getLogger();
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("MLet service " + objectName + " preRegistered successfully");
return objectName;
}
public void postRegister(Boolean registrationDone)
{
Logger logger = getLogger();
if (!registrationDone.booleanValue())
{
server = null;
if (logger.isEnabledFor(Logger.INFO)) logger.info("MLet service " + objectName + " was not registered");
}
else
{
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("MLet service " + objectName + " postRegistered successfully");
}
}
public void preDeregister() throws Exception
{
Logger logger = getLogger();
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("MLet service " + objectName + " preDeregistered successfully");
}
public void postDeregister()
{
Logger logger = getLogger();
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("MLet service " + objectName + " postDeregistered successfully");
}
public void addURL(String url) throws ServiceNotFoundException
{
addURL(createURL(url));
}
public void addURL(URL url)
{
Logger logger = getLogger();
if (!Arrays.asList(getURLs()).contains(url))
{
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("Adding URL to this MLet (" + objectName + ") classpath: " + url);
super.addURL(url);
}
else
{
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("URL already present in this MLet (" + objectName + ") classpath: " + url);
}
}
public Class loadClass(String name, ClassLoaderRepository repository) throws ClassNotFoundException
{
if (repository == null)
{
Class cls = loadClassLocally(name);
return cls;
}
else
{
try
{
Class cls = loadClassLocally(name);
return cls;
}
catch (ClassNotFoundException x)
{
// Not found locally, try the given repository
Class cls = loadClassFromRepository(name, repository);
return cls;
}
}
}
/**
* Loads the given class from this MLet only (with the usual parent delegation mechanism); the
* ClassLoaderRepository is not asked to load the class.
*
* @param name The name of the class to load.
* @return The loaded class
* @throws ClassNotFoundException
*/
private Class loadClassLocally(String name) throws ClassNotFoundException
{
// Here I must call super.loadClass(name) but not delegate to the CLR when I arrive to MLet.findClass
// I cannot call findClassLocally directly because otherwise the mechanism of parent delegation
// implemented in loadClass() is skipped and the parent loaders do not have the chance to
// load the given class
try
{
loadingOnlyLocally.set(Boolean.TRUE);
return loadClass(name);
}
finally
{
loadingOnlyLocally.set(Boolean.FALSE);
}
}
/**
* Loads the given class from the given non-null ClassLoaderRepository using
* {@link ClassLoaderRepository#loadClassBefore}
*/
private Class loadClassFromRepository(String name, ClassLoaderRepository repository) throws ClassNotFoundException
{
return repository.loadClassBefore(this, name);
}
protected Class findClass(String name) throws ClassNotFoundException
{
Logger logger = getLogger();
boolean trace = logger.isEnabledFor(Logger.TRACE);
// It may be possible that loading started with this MLet, then delegated to the CLR
// and came again to query this MLet which, if not stopped, will delegate to the CLR
// again in an endless loop. This is possible if this MLet is the parent of a child
// MLet registered before its parent.
if (loadingWithRepository.get() == Boolean.TRUE)
{
if (trace) logger.trace("MLet " + this + " is recursively calling itself to load class " + name + ": skipping further searches");
throw new ClassNotFoundException(name);
}
if (trace) logger.trace("Finding class " + name + "...");
try
{
Class cls = findClassLocally(name);
if (trace) logger.trace("Class " + name + " found in this MLet's classpath " + this);
return cls;
}
catch (ClassNotFoundException x)
{
if (!isDelegateToCLR())
{
if (trace) logger.trace("MLet " + this + " does not delegate to the ClassLoaderRepository");
throw x;
}
if (loadingOnlyLocally.get() == Boolean.TRUE) throw x;
if (server == null) throw x;
if (trace) logger.trace("Class " + name + " not found in this MLet's classpath " + this + ", trying the ClassLoaderRepository...", x);
try
{
loadingWithRepository.set(Boolean.TRUE);
ClassLoaderRepository repository = server.getClassLoaderRepository();
Class cls = loadClassFromRepository(name, repository);
if (trace) logger.trace("Class " + name + " found with ClassLoaderRepository " + repository);
return cls;
}
catch (ClassNotFoundException xx)
{
if (trace) logger.trace("Class " + name + " not found in ClassLoaderRepository, giving up", xx);
throw new ClassNotFoundException(name);
}
finally
{
loadingWithRepository.set(Boolean.FALSE);
}
}
}
private Class findClassLocally(String name) throws ClassNotFoundException
{
return super.findClass(name);
}
public Set getMBeansFromURL(String url) throws ServiceNotFoundException
{
return getMBeansFromURL(createURL(url));
}
public Set getMBeansFromURL(URL url) throws ServiceNotFoundException
{
if (url == null) throw new ServiceNotFoundException("Cannot load MBeans from null URL");
Logger logger = getLogger();
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("MLet " + this + ", reading MLET file from " + url);
InputStream is = null;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BufferedOutputStream os = new BufferedOutputStream(baos);
try
{
is = url.openStream();
readFromAndWriteTo(is, os);
}
catch (IOException x)
{
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("Cannot read input stream from URL " + url, x);
throw new ServiceNotFoundException(x.toString());
}
finally
{
try
{
if (is != null) is.close();
os.close();
}
catch (IOException ignored)
{
}
}
String mletFileContent = null;
try
{
mletFileContent = new String(baos.toByteArray(), "UTF-8");
}
catch (UnsupportedEncodingException x)
{
mletFileContent = baos.toString();
}
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("MLet File content is:\n" + mletFileContent);
return parseMLetFile(mletFileContent, url);
}
private Set parseMLetFile(String content, URL mletFileURL) throws ServiceNotFoundException
{
Logger logger = getLogger();
try
{
HashSet mbeans = new HashSet();
MLetParser parser = new MLetParser(this);
List tags = parser.parse(content);
for (int i = 0; i < tags.size(); ++i)
{
MLetTag tag = (MLetTag)tags.get(i);
// Add the MBean's codebase to the MLet classloader
String[] jars = tag.parseArchive();
for (int j = 0; j < jars.length; ++j)
{
String jar = jars[j];
URL codebase = handleCheck(tag, jar, mletFileURL, mbeans);
URL archiveURL = tag.createArchiveURL(codebase, jar);
addURL(archiveURL);
}
// Create and register the MBean
Object obj = createMBean(tag);
mbeans.add(obj);
}
return mbeans;
}
catch (MLetParseException x)
{
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("Cannot parse MLet file", x);
throw new ServiceNotFoundException(x.toString());
}
}
/**
* This method handle the call to {@link #check}, a method that it's a big mistake in JMX 1.2
*/
private URL handleCheck(MLetTag tag, String archive, URL mletFileURL, Set mbeans)
{
HashMap map = new HashMap();
map.put("codebaseURL", tag.normalizeCodeBase(mletFileURL));
map.put("codebase", tag.getCodeBase());
map.put("archive", tag.getArchive());
map.put("code", tag.getCode());
map.put("object", tag.getObject());
map.put("name", tag.getObjectName());
map.put("version", tag.getVersion());
MLetContent mletContent = new MLetContent(mletFileURL, map);
try
{
// JMX 1.2 FAAAAANTASTIC check method
return check(mletContent.getVersion(), mletContent.getCodeBase(), archive, mletContent);
}
catch (Throwable x)
{
mbeans.add(x);
return null;
}
}
/**
* This method is called when an MLet file has been parsed and before its information is used by this MLet.
* By overriding this method subclasses have the possibility to perform caching and versioning of jars,
* but unfortunately it contains as parameter a package private class, that thus forbids overriding: a big
* mistake in the JMX 1.2 specification.
*
* @since JMX 1.2
*/
protected URL check(String version, URL codebase, String archive, MLetContent content) throws Exception
{
return codebase;
}
private Object createMBean(MLetTag tag) throws ServiceNotFoundException
{
if (server == null) throw new ServiceNotFoundException("MLet not registered on the MBeanServer");
Logger logger = getLogger();
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("MLet " + this + ", creating MBean from\n" + tag);
try
{
Object mbean = null;
if (tag.getObject() != null)
{
// Read the file from the codebase URLs of this classloader
String name = tag.getObject();
InputStream is = getResourceAsStream(name);
if (is == null) throw new ServiceNotFoundException("Cannot find serialized MBean " + name + " in MLet " + this);
InputStream bis = new BufferedInputStream(is);
// Deserialize using the MLet classloader
ObjectInputStream ois = new ClassLoaderObjectInputStream(bis, this);
mbean = ois.readObject();
}
else
{
// Instantiate using the MLet classloader
String clsName = tag.getCode();
Object[] args = tag.getArguments();
String[] params = tag.getSignature();
mbean = server.instantiate(clsName, objectName, args, params);
}
ObjectName objectName = tag.getObjectName();
ObjectInstance instance = server.registerMBean(mbean, objectName);
return instance;
}
catch (Throwable t)
{
return t;
}
}
protected String findLibrary(String libraryName)
{
// When asked to load a library, I should convert the library name to the system specific name
// For example if libraryName == "stat", on Solaris the conversion yields libstat.so, on Windows yields stat.dll
final String sysLibraryName = System.mapLibraryName(libraryName);
// Try to load the native libaray from jar only using the library name
String path = copyLibrary(sysLibraryName);
if (path != null) return path;
// Library not found so try to load the library using the os specific architecture
String osPath = (String)AccessController.doPrivileged(new PrivilegedAction()
{
public Object run()
{
StringBuffer buffer = new StringBuffer();
buffer.append(System.getProperty("os.name")).append(File.separator);
buffer.append(System.getProperty("os.arch")).append(File.separator);
buffer.append(System.getProperty("os.version")).append(File.separator);
buffer.append("lib").append(File.separator).append(sysLibraryName);
return buffer.toString();
}
});
osPath = removeSpaces(osPath);
return copyLibrary(osPath);
}
private String copyLibrary(String library)
{
Logger logger = getLogger();
library = library.replace('\\', '/');
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("Loading library " + library);
URL libraryURL = getResource(library);
InputStream is = null;
OutputStream os = null;
try
{
try
{
is = getResourceAsStream(library);
if (is == null) return null;
if (!(is instanceof BufferedInputStream)) is = new BufferedInputStream(is);
File localLibrary = new File(getLibraryDirectory(), library);
URL localLibraryURL = localLibrary.toURL();
// The library is local and its directory is in the classpath of this MLet
if (localLibraryURL.equals(libraryURL)) return localLibrary.getCanonicalPath();
// Copy the library (that can be remote) locally, overwriting old versions
try
{
os = new BufferedOutputStream(new FileOutputStream(localLibrary));
readFromAndWriteTo(is, os);
return localLibrary.getCanonicalPath();
}
finally
{
if (os != null) os.close();
}
}
finally
{
if (is != null) is.close();
}
}
catch (IOException x)
{
if (logger.isEnabledFor(Logger.TRACE)) logger.trace("Cannot copy the library to the library directory " + getLibraryDirectory(), x);
return null;
}
}
private void readFromAndWriteTo(InputStream is, OutputStream os) throws IOException
{
byte[] buffer = new byte[64];
int read = -1;
while ((read = is.read(buffer)) >= 0) os.write(buffer, 0, read);
}
private String removeSpaces(String string)
{
int space = -1;
StringBuffer buffer = new StringBuffer();
while ((space = string.indexOf(' ')) >= 0)
{
buffer.append(string.substring(0, space));
string = string.substring(space + 1);
}
buffer.append(string);
return buffer.toString();
}
public String getLibraryDirectory()
{
return libraryDir;
}
public void setLibraryDirectory(String libdir)
{
libraryDir = libdir;
}
private boolean isDelegateToCLR()
{
return delegateToCLR;
}
private void setDelegateToCLR(boolean delegateToCLR)
{
this.delegateToCLR = delegateToCLR;
}
private URL createURL(String urlString) throws ServiceNotFoundException
{
try
{
URL url = new URL(urlString);
return url;
}
catch (MalformedURLException x)
{
throw new ServiceNotFoundException(x.toString());
}
}
private Logger getLogger()
{
return Log.getLogger(getClass().getName());
}
/**
* Restores this MLet content from the given ObjectInput. Implementation of this method is optional,
* and if not implemented throws an UnsupportedOperationException.
*/
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
{
throw new UnsupportedOperationException("MLet.readExternal");
}
/**
* Stores this MLet content in the given ObjectOutput. Implementation of this method is optional,
* and if not implemented throws an UnsupportedOperationException.
*/
public void writeExternal(ObjectOutput out) throws IOException
{
throw new UnsupportedOperationException("MLet.writeExternal");
}
}