diff options
Diffstat (limited to 'java/broker/src/main/java/org/apache/qpid/server/configuration/updater/TaskExecutor.java')
| -rw-r--r-- | java/broker/src/main/java/org/apache/qpid/server/configuration/updater/TaskExecutor.java | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/java/broker/src/main/java/org/apache/qpid/server/configuration/updater/TaskExecutor.java b/java/broker/src/main/java/org/apache/qpid/server/configuration/updater/TaskExecutor.java new file mode 100644 index 0000000000..671104d413 --- /dev/null +++ b/java/broker/src/main/java/org/apache/qpid/server/configuration/updater/TaskExecutor.java @@ -0,0 +1,324 @@ +/* + * + * 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.qpid.server.configuration.updater; + +import java.security.AccessController; +import java.security.PrivilegedActionException; +import java.security.PrivilegedExceptionAction; +import java.util.List; +import java.util.concurrent.Callable; +import java.util.concurrent.CancellationException; +import java.util.concurrent.ExecutionException; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.Future; +import java.util.concurrent.RunnableFuture; +import java.util.concurrent.ThreadFactory; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicReference; + +import javax.security.auth.Subject; + +import org.apache.log4j.Logger; +import org.apache.qpid.server.logging.LogActor; +import org.apache.qpid.server.logging.actors.CurrentActor; +import org.apache.qpid.server.model.State; +import org.apache.qpid.server.security.SecurityManager; + +public class TaskExecutor +{ + private static final String TASK_EXECUTION_THREAD_NAME = "Broker-Configuration-Thread"; + private static final Logger LOGGER = Logger.getLogger(TaskExecutor.class); + + private volatile Thread _taskThread; + private final AtomicReference<State> _state; + private volatile ExecutorService _executor; + + public TaskExecutor() + { + _state = new AtomicReference<State>(State.INITIALISING); + } + + public State getState() + { + return _state.get(); + } + + public void start() + { + if (_state.compareAndSet(State.INITIALISING, State.ACTIVE)) + { + LOGGER.debug("Starting task executor"); + _executor = Executors.newFixedThreadPool(1, new ThreadFactory() + { + @Override + public Thread newThread(Runnable r) + { + _taskThread = new Thread(r, TASK_EXECUTION_THREAD_NAME); + return _taskThread; + } + }); + LOGGER.debug("Task executor is started"); + } + } + + public void stopImmediately() + { + if (_state.compareAndSet(State.ACTIVE, State.STOPPED)) + { + ExecutorService executor = _executor; + if (executor != null) + { + LOGGER.debug("Stopping task executor immediately"); + List<Runnable> cancelledTasks = executor.shutdownNow(); + if (cancelledTasks != null) + { + for (Runnable runnable : cancelledTasks) + { + if (runnable instanceof RunnableFuture<?>) + { + ((RunnableFuture<?>) runnable).cancel(true); + } + } + } + _executor = null; + _taskThread = null; + LOGGER.debug("Task executor was stopped immediately. Number of unfinished tasks: " + cancelledTasks.size()); + } + } + } + + public void stop() + { + if (_state.compareAndSet(State.ACTIVE, State.STOPPED)) + { + ExecutorService executor = _executor; + if (executor != null) + { + LOGGER.debug("Stopping task executor"); + executor.shutdown(); + _executor = null; + _taskThread = null; + LOGGER.debug("Task executor is stopped"); + } + } + } + + Future<?> submit(Callable<?> task) + { + checkState(); + if (LOGGER.isDebugEnabled()) + { + LOGGER.debug("Submitting task: " + task); + } + Future<?> future = null; + if (isTaskExecutorThread()) + { + Object result = executeTaskAndHandleExceptions(task); + return new ImmediateFuture(result); + } + else + { + future = _executor.submit(new CallableWrapper(task)); + } + return future; + } + + public Object submitAndWait(Callable<?> task) throws CancellationException + { + try + { + Future<?> future = submit(task); + return future.get(); + } + catch (InterruptedException e) + { + throw new RuntimeException("Task execution was interrupted: " + task, e); + } + catch (ExecutionException e) + { + Throwable cause = e.getCause(); + if (cause instanceof RuntimeException) + { + throw (RuntimeException) cause; + } + else if (cause instanceof Exception) + { + throw new RuntimeException("Failed to execute user task: " + task, cause); + } + else if (cause instanceof Error) + { + throw (Error) cause; + } + else + { + throw new RuntimeException("Failed to execute user task: " + task, cause); + } + } + } + + public boolean isTaskExecutorThread() + { + return Thread.currentThread() == _taskThread; + } + + private void checkState() + { + if (_state.get() != State.ACTIVE) + { + throw new IllegalStateException("Task executor is not in ACTIVE state"); + } + } + + private Object executeTaskAndHandleExceptions(Callable<?> userTask) + { + try + { + return executeTask(userTask); + } + catch (Exception e) + { + if (e instanceof RuntimeException) + { + throw (RuntimeException) e; + } + throw new RuntimeException("Failed to execute user task: " + userTask, e); + } + } + + private Object executeTask(Callable<?> userTask) throws Exception + { + if (LOGGER.isDebugEnabled()) + { + LOGGER.debug("Performing task " + userTask); + } + Object result = userTask.call(); + if (LOGGER.isDebugEnabled()) + { + LOGGER.debug("Task " + userTask + " is performed successfully with result:" + result); + } + return result; + } + + private class CallableWrapper implements Callable<Object> + { + private Callable<?> _userTask; + private Subject _securityManagerSubject; + private LogActor _actor; + private Subject _contextSubject; + + public CallableWrapper(Callable<?> userWork) + { + _userTask = userWork; + _securityManagerSubject = SecurityManager.getThreadSubject(); + _actor = CurrentActor.get(); + _contextSubject = Subject.getSubject(AccessController.getContext()); + } + + @Override + public Object call() throws Exception + { + SecurityManager.setThreadSubject(_securityManagerSubject); + CurrentActor.set(_actor); + + try + { + Object result = null; + try + { + result = Subject.doAs(_contextSubject, new PrivilegedExceptionAction<Object>() + { + @Override + public Object run() throws Exception + { + return executeTask(_userTask); + } + }); + } + catch (PrivilegedActionException e) + { + throw e.getException(); + } + return result; + } + finally + { + try + { + CurrentActor.remove(); + } + catch (Exception e) + { + LOGGER.warn("Unxpected exception on current actor removal", e); + } + try + { + SecurityManager.setThreadSubject(null); + } + catch (Exception e) + { + LOGGER.warn("Unxpected exception on nullifying of subject for a security manager", e); + } + } + } + } + + private class ImmediateFuture implements Future<Object> + { + private Object _result; + + public ImmediateFuture(Object result) + { + super(); + this._result = result; + } + + @Override + public boolean cancel(boolean mayInterruptIfRunning) + { + return false; + } + + @Override + public boolean isCancelled() + { + return false; + } + + @Override + public boolean isDone() + { + return true; + } + + @Override + public Object get() + { + return _result; + } + + @Override + public Object get(long timeout, TimeUnit unit) + { + return get(); + } + } +} |