| /* |
| * 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.felix.cm.impl; |
| |
| import java.security.AccessControlContext; |
| import java.security.AccessController; |
| import java.security.PrivilegedActionException; |
| import java.security.PrivilegedExceptionAction; |
| import java.util.concurrent.BlockingDeque; |
| import java.util.concurrent.LinkedBlockingDeque; |
| |
| import org.osgi.service.log.LogService; |
| |
| |
| /** |
| * The <code>UpdateThread</code> is the thread used to update managed services |
| * and managed service factories as well as to send configuration events. |
| */ |
| public class UpdateThread implements Runnable |
| { |
| |
| // the thread group into which the worker thread will be placed |
| private final ThreadGroup workerThreadGroup; |
| |
| // the thread's base name |
| private final String workerBaseName; |
| |
| // the queue of Runnable instances to be run |
| private final BlockingDeque<Runnable> updateTasks = new LinkedBlockingDeque<>(); |
| |
| // the actual thread |
| private volatile Thread worker; |
| |
| // the access control context |
| private final AccessControlContext acc; |
| |
| public UpdateThread( final ThreadGroup tg, final String name ) |
| { |
| this.workerThreadGroup = tg; |
| this.workerBaseName = name; |
| this.acc = AccessController.getContext(); |
| } |
| |
| |
| // waits on Runnable instances coming into the queue. As instances come |
| // in, this method calls the Runnable.run method, logs any exception |
| // happening and keeps on waiting for the next Runnable. If the Runnable |
| // taken from the queue is this thread instance itself, the thread |
| // terminates. |
| @Override |
| public void run() |
| { |
| try |
| { |
| Runnable task; |
| // return if the task is this thread itself |
| while ((task = updateTasks.take()) != this) |
| { |
| // otherwise execute the task, log any issues |
| try |
| { |
| // set the thread name indicating the current task |
| Thread.currentThread().setName( workerBaseName + " (" + task + ")" ); |
| |
| Log.logger.log( LogService.LOG_DEBUG, "Running task {0}", new Object[] |
| { task } ); |
| |
| run0(task); |
| } |
| catch ( Throwable t ) |
| { |
| Log.logger.log( LogService.LOG_ERROR, "Unexpected problem executing task", t ); |
| } |
| finally |
| { |
| // reset the thread name to "idle" |
| Thread.currentThread().setName( workerBaseName ); |
| } |
| } |
| } |
| catch (InterruptedException e) |
| { |
| // don't care |
| } |
| } |
| |
| void run0(final Runnable task) throws Throwable { |
| if (System.getSecurityManager() != null) { |
| try { |
| AccessController.doPrivileged( |
| new PrivilegedExceptionAction<Void>() { |
| @Override |
| public Void run() throws Exception { |
| task.run(); |
| return null; |
| } |
| }, |
| acc |
| ); |
| } |
| catch (PrivilegedActionException pae) { |
| throw pae.getException(); |
| } |
| } |
| else { |
| task.run(); |
| } |
| } |
| |
| /** |
| * Starts processing the queued tasks. This method does nothing if the |
| * worker has already been started. |
| */ |
| synchronized void start() |
| { |
| if ( this.worker == null ) |
| { |
| Thread workerThread = new Thread( workerThreadGroup, this, workerBaseName ); |
| workerThread.setDaemon( true ); |
| workerThread.start(); |
| this.worker = workerThread; |
| } |
| } |
| |
| |
| /** |
| * Terminates the worker thread and waits for the thread to have processed |
| * all outstanding events up to and including the termination job. All |
| * jobs {@link #schedule(Runnable) scheduled} after termination has been |
| * initiated will not be processed any more. This method does nothing if |
| * the worker thread is not currently active. |
| * <p> |
| * If the worker thread does not terminate within 5 seconds it is killed |
| * by calling the (deprecated) <code>Thread.stop()</code> method. It may |
| * be that the worker thread may be blocked by a deadlock (it should not, |
| * though). In this case hope is that <code>Thread.stop()</code> will be |
| * able to released that deadlock at the expense of one or more tasks to |
| * not be executed any longer.... In any case an ERROR message is logged |
| * with the LogService in this situation. |
| */ |
| synchronized void terminate() |
| { |
| if ( this.worker != null ) |
| { |
| Thread workerThread = this.worker; |
| this.worker = null; |
| |
| updateTasks.offerFirst( this ); |
| |
| // wait for all updates to terminate (<= 10 seconds !) |
| try |
| { |
| workerThread.join( 5000 ); |
| } |
| catch ( InterruptedException ie ) |
| { |
| // don't really care |
| } |
| |
| if ( workerThread.isAlive() ) |
| { |
| Log.logger.log( LogService.LOG_ERROR, |
| "Worker thread {0} did not terminate within 5 seconds; trying to kill", new Object[] |
| { workerBaseName } ); |
| workerThread.interrupt(); |
| } |
| } |
| } |
| |
| |
| // queue the given runnable to be run as soon as possible |
| void schedule( Runnable update ) |
| { |
| Log.logger.log( LogService.LOG_DEBUG, "Scheduling task {0}", new Object[] |
| { update } ); |
| |
| // append to the task queue |
| updateTasks.offer( update ); |
| } |
| } |