/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.openjpa.enhance;
import java.lang.instrument.Instrumentation;
import java.security.AccessController;
import java.util.List;
import org.apache.openjpa.conf.OpenJPAConfiguration;
import org.apache.openjpa.conf.OpenJPAConfigurationImpl;
import org.apache.openjpa.lib.conf.Configuration;
import org.apache.openjpa.lib.conf.Configurations;
import org.apache.openjpa.lib.log.Log;
import org.apache.openjpa.lib.util.J2DoPrivHelper;
import org.apache.openjpa.lib.util.Options;
import org.apache.openjpa.util.ClassResolver;
/**
* <p>
* Java agent that makes persistent classes work with OpenJPA at runtime. This
* is achieved by either running the enhancer on the classes as they are loaded,
* or by redefining the classes on the fly. The agent is launched at JVM startup
* from the command line:
* </p>
*
* <p>
* <code>java -javaagent:openjpa.jar[=<options>]</code> The options string
* should be formatted as a OpenJPA plugin, and may contain any properties
* understood by the OpenJPA enhancer or any configuration properties. For
* example:
* </p>
*
* <p>
* <code>java -javaagent:openjpa.jar</code>
* </p>
*
* <p>
* By default, if specified, the agent runs the OpenJPA enhancer on all classes
* listed in the first persistence unit as they are loaded, and redefines all
* other persistent classes when they are encountered. To disable enhancement at
* class-load time and rely solely on the redefinition logic, set the
* ClassLoadEnhancement flag to false. To disable redefinition and rely solely
* on pre-deployment or class-load enhancement, set the RuntimeRedefinition flag
* to false.
* </p>
*
* <p>
* <code>java -javaagent:openjpa.jar=ClassLoadEnhancement=false</code>
* </p>
*
* @author Abe White
* @author Patrick Linskey
*/
public class PCEnhancerAgent {
private static boolean loadAttempted = false;
private static boolean loadSuccessful = false;
private static boolean disableDynamicAgent = false;
/**
* @return True if the Agent has ran successfully. False otherwise.
*/
public static synchronized boolean getLoadSuccessful() {
return loadSuccessful;
}
/**
* @return True if the dynamic agent was disabled via configuration.
*/
public static void disableDynamicAgent(){
disableDynamicAgent=true;
}
/**
* @param log
* @return True if the agent is loaded successfully
*/
public static synchronized boolean loadDynamicAgent(Log log) {
if (loadAttempted == false && disableDynamicAgent == false) {
Instrumentation inst =
InstrumentationFactory.getInstrumentation(log);
if (inst != null) {
premain("", inst);
return true;
}
// If we successfully get the Instrumentation, we will call premain
// where loadAttempted will be set to true. This case is the path
// where we were unable to get Instrumentation so we need to set the
// loadAttempted flag to true. We do this so we will only run
// through this code one time.
loadAttempted = true;
}
return false;
}
public static void premain(String args, Instrumentation inst) {
// If the enhancer has already completed, noop. This can happen
// if runtime enhancement is specified via javaagent, and
// openJPA tries to dynamically enhance.
// The agent will be disabled when running in an application
// server.
synchronized (PCEnhancerAgent.class) {
if (loadAttempted == true) {
return;
}
// See the comment in loadDynamicAgent as to why we set this to true
// in multiple places.
loadAttempted = true;
}
Options opts = Configurations.parseProperties(args);
if (opts.containsKey("ClassLoadEnhancement") ||
opts.containsKey("classLoadEnhancement")) {
if (opts.getBooleanProperty(
"ClassLoadEnhancement", "classLoadEnhancement", true))
registerClassLoadEnhancer(inst, opts);
}
else if (opts.containsKey("RuntimeEnhancement") ||
opts.containsKey("runtimeEnhancement")) {
// Deprecated property setting
if (opts.getBooleanProperty(
"RuntimeEnhancement", "runtimeEnhancement", true))
registerClassLoadEnhancer(inst, opts);
} else {
// if neither is set, then we should be turning it on. We need this
// logic instead of just a getBooleanProperty() because of the
// backwards-compat logic flow.
registerClassLoadEnhancer(inst, opts);
}
if (opts.getBooleanProperty(
"RuntimeRedefinition", "runtimeRedefinition", true)) {
InstrumentationFactory.setInstrumentation(inst);
} else {
InstrumentationFactory.setDynamicallyInstallAgent(false);
}
loadSuccessful = true;
}
private static void registerClassLoadEnhancer(Instrumentation inst,
Options opts) {
List<String> anchors = Configurations.
getFullyQualifiedAnchorsInPropertiesLocation(opts);
for (String a : anchors) {
Options clonedOptions = (Options) opts.clone();
clonedOptions.setProperty("properties", a);
OpenJPAConfiguration conf = new OpenJPAConfigurationImpl();
Configurations.populateConfiguration(conf, clonedOptions);
// don't allow connections
conf.setConnectionUserName(null);
conf.setConnectionPassword(null);
conf.setConnectionURL(null);
conf.setConnectionDriverName(null);
conf.setConnectionFactoryName(null);
// set single class resolver
final ClassLoader tmpLoader = AccessController
.doPrivileged(J2DoPrivHelper
.newTemporaryClassLoaderAction(AccessController
.doPrivileged(J2DoPrivHelper.getContextClassLoaderAction())
));
conf.setClassResolver(new ClassResolver() {
public ClassLoader getClassLoader(Class context,
ClassLoader env) {
return tmpLoader;
}
});
conf.setReadOnly(Configuration.INIT_STATE_FREEZING);
conf.instantiateAll(); // avoid threading issues
PCClassFileTransformer transformer = new PCClassFileTransformer
(conf.newMetaDataRepositoryInstance(), clonedOptions,
tmpLoader);
inst.addTransformer(transformer);
conf.close();
}
}
}