/**
* Installs a Java agent using the Java attach API. This API is available under different access
* routes for different JVMs and JVM versions or it might not be available at all. If a Java agent
* cannot be installed by using the supplied attachment provider, a {@link IllegalStateException}
* is thrown.
*
* @param attachmentProvider The attachment provider to use for the installation.
* @return An instrumentation instance representing the currently running JVM.
*/
public static synchronized Instrumentation install(AttachmentProvider attachmentProvider) {
Instrumentation instrumentation = doGetInstrumentation();
if (instrumentation != null) {
return instrumentation;
}
AttachmentProvider.Accessor accessor = attachmentProvider.attempt();
if (accessor.isAvailable()) {
try {
doInstall(accessor);
} catch (Exception exception) {
throw new IllegalStateException(
"Error during attachment using: " + attachmentProvider, exception);
}
return getInstrumentation();
} else {
throw new IllegalStateException(
"This JVM does not support attachment using: " + attachmentProvider);
}
}
/**
* Performs the actual installation of the Byte Buddy agent.
*
* @param accessor An available accessor for accessing the Java attachment API.
* @throws Exception If the installation is not possible.
*/
private static void doInstall(AttachmentProvider.Accessor accessor) throws Exception {
Class<?> virtualMachine = accessor.getVirtualMachineType();
Object virtualMachineInstance =
virtualMachine
.getDeclaredMethod(ATTACH_METHOD_NAME, String.class)
.invoke(STATIC_MEMBER, accessor.getProcessId());
File agentJar = File.createTempFile(AGENT_FILE_NAME, JAR_FILE_EXTENSION);
try {
saveAgentJar(agentJar);
virtualMachine
.getDeclaredMethod(LOAD_AGENT_METHOD_NAME, String.class, String.class)
.invoke(virtualMachineInstance, agentJar.getAbsolutePath(), WITHOUT_ARGUMENTS);
} finally {
try {
virtualMachine.getDeclaredMethod(DETACH_METHOD_NAME).invoke(virtualMachineInstance);
} finally {
if (!agentJar.delete()) {
Logger.getAnonymousLogger().info("Cannot delete temporary file: " + agentJar);
}
}
}
}
