/**
* The contents of this file are subject to the OpenMRS Public License
* Version 1.0 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://license.openmrs.org
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
* License for the specific language governing rights and limitations
* under the License.
*
* Copyright (C) OpenMRS, LLC. All Rights Reserved.
*/
package org.openmrs.api.context;
import org.openmrs.api.APIAuthenticationException;
import org.openmrs.api.APIException;
import org.openmrs.api.OpenmrsService;
import org.openmrs.module.Module;
import org.openmrs.module.ModuleException;
import org.openmrs.module.ModuleFactory;
import org.openmrs.scheduler.Task;
import org.openmrs.scheduler.timer.TimerSchedulerTask;
import org.openmrs.util.OpenmrsSecurityManager;
/**
* This class allows certain tasks to run with elevated privileges. Primary use is scheduling and
* module startup when there is no user to authenticate as.
*/
public class Daemon {
/**
* The uuid defined for the daemon user object
*/
protected static final String DAEMON_USER_UUID = "A4F30A1B-5EB9-11DF-A648-37A07F9C90FB";
private static final ThreadLocal<Boolean> isDaemonThread = new ThreadLocal<Boolean>();
/**
* This method should not be called directly. The {@link ModuleFactory#startModule(Module)}
* method uses this to start the given module in a new thread that is authenticated as the
* daemon user
*
* @param module the module to start
* @returns the module returned from {@link ModuleFactory#startModuleInternal(Module)}
*/
public static Module startModule(final Module module) throws ModuleException {
// create a new thread and execute that task in it
DaemonThread startModuleThread = new DaemonThread() {
@Override
public void run() {
isDaemonThread.set(true);
try {
Context.openSession();
returnedObject = ModuleFactory.startModuleInternal(module);
}
catch (Throwable t) {
exceptionThrown = t;
}
finally {
Context.closeSession();
}
}
};
startModuleThread.start();
// wait for the "startModule" thread to finish
try {
startModuleThread.join();
}
catch (InterruptedException e) {
// ignore
}
if (startModuleThread.exceptionThrown != null) {
if (startModuleThread.exceptionThrown instanceof ModuleException)
throw (ModuleException) startModuleThread.exceptionThrown;
else
throw new ModuleException("Unable to start module as Daemon", startModuleThread.exceptionThrown);
}
return (Module) startModuleThread.returnedObject;
}
/**
* Executes the given task in a new thread that is authenticated as the daemon user. <br/>
* <br/>
* This can only be called from {@link TimerSchedulerTask} during actual task execution
*
* @param task the task to run
* @should not be called from other methods other than TimerSchedulerTask
* @should not throw error if called from a TimerSchedulerTask class
*/
public static void executeScheduledTask(final Task task) throws Throwable {
// quick check to make sure we're only being called by ourselves
//Class<?> callerClass = Reflection.getCallerClass(0);
Class<?> callerClass = new OpenmrsSecurityManager().getCallerClass(0);
if (!TimerSchedulerTask.class.isAssignableFrom(callerClass))
throw new APIException("This method can only be called from the TimerSchedulerTask class, not "
+ callerClass.getName());
// now create a new thread and execute that task in it
DaemonThread executeTaskThread = new DaemonThread() {
@Override
public void run() {
isDaemonThread.set(true);
try {
Context.openSession();
task.execute();
}
catch (Throwable t) {
exceptionThrown = t;
}
finally {
Context.closeSession();
}
}
};
executeTaskThread.start();
// wait for the "executeTaskThread" thread to finish
try {
executeTaskThread.join();
}
catch (InterruptedException e) {
// ignore
}
if (executeTaskThread.exceptionThrown != null)
throw executeTaskThread.exceptionThrown;
}
/**
* Call this method if you are inside a Daemon thread (for example in a Module activator or a
* scheduled task) and you want to start up a new parallel Daemon thread. You may only call this
* method from a Daemon thread.
*
* @param runnable what to run in a new thread
* @return the newly spawned {@link Thread}
* @should throw error if called from a non daemon thread
* @should not throw error if called from a daemon thread
*/
public static Thread runInNewDaemonThread(final Runnable runnable) {
// make sure we're already in a daemon thread
if (!isDaemonThread())
throw new APIAuthenticationException("Only daemon threads can spawn new daemon threads");
// we should consider making DaemonThread public, so the caller can access returnedObject and exceptionThrown
DaemonThread thread = new DaemonThread() {
@Override
public void run() {
isDaemonThread.set(true);
try {
Context.openSession();
runnable.run();
}
finally {
Context.closeSession();
}
}
};
thread.start();
return thread;
}
/**
* @return true if the current thread was started by this class and so is a daemon thread that
* has all privileges
* @see Context#hasPrivilege(String)
*/
public static boolean isDaemonThread() {
Boolean b = isDaemonThread.get();
if (b == null)
return false;
else
return b.booleanValue();
}
/**
* Calls the {@link OpenmrsService#onStartup()} method, as a daemon, for an instance
* implementing the {@link OpenmrsService} interface.
*
* @param openmrsService instance implementing the {@link OpenmrsService} interface.
* @since 1.9
*/
public static void runStartupForService(final OpenmrsService service) throws ModuleException {
DaemonThread onStartupThread = new DaemonThread() {
@Override
public void run() {
isDaemonThread.set(true);
try {
Context.openSession();
service.onStartup();
}
catch (Throwable t) {
exceptionThrown = t;
}
finally {
Context.closeSession();
}
}
};
onStartupThread.start();
// wait for the "onStartup" thread to finish
try {
onStartupThread.join();
}
catch (InterruptedException e) {
// ignore
e.printStackTrace();
}
if (onStartupThread.exceptionThrown != null) {
if (onStartupThread.exceptionThrown instanceof ModuleException)
throw (ModuleException) onStartupThread.exceptionThrown;
else
throw new ModuleException("Unable to run onStartup() method as Daemon", onStartupThread.exceptionThrown);
}
}
/**
* Thread class used by the {@link Daemon#startModule(Module)} and
* {@link Daemon#executeScheduledTask(Task)} methods so that the returned object and the
* exception thrown can be returned to calling class
*/
private static class DaemonThread extends Thread {
/**
* The object returned from the method called in {@link #run()}
*/
protected Object returnedObject = null;
/**
* The exception thrown (if any) by the method called in {@link #run()}
*/
protected Throwable exceptionThrown = null;
}
}