| /* |
| * 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.cloudstack.managed.context.impl; |
| |
| import java.util.List; |
| import java.util.Stack; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.CopyOnWriteArrayList; |
| |
| import org.apache.logging.log4j.Logger; |
| import org.apache.logging.log4j.LogManager; |
| |
| import org.apache.cloudstack.managed.context.ManagedContext; |
| import org.apache.cloudstack.managed.context.ManagedContextListener; |
| import org.apache.cloudstack.managed.context.ManagedContextUtils; |
| import org.apache.cloudstack.managed.threadlocal.ManagedThreadLocal; |
| |
| public class DefaultManagedContext implements ManagedContext { |
| |
| protected Logger logger = LogManager.getLogger(getClass()); |
| |
| List<ManagedContextListener<?>> listeners = new CopyOnWriteArrayList<ManagedContextListener<?>>(); |
| |
| @Override |
| public void registerListener(ManagedContextListener<?> listener) { |
| listeners.add(listener); |
| } |
| |
| @Override |
| public void unregisterListener(ManagedContextListener<?> listener) { |
| listeners.remove(listener); |
| } |
| |
| @Override |
| public void runWithContext(final Runnable run) { |
| try { |
| callWithContext(new Callable<Object>() { |
| @Override |
| public Object call() throws Exception { |
| run.run(); |
| return null; |
| } |
| }); |
| } catch (Exception e) { |
| /* Only care about non-checked exceptions |
| * as the nature of runnable prevents checked |
| * exceptions from happening |
| */ |
| ManagedContextUtils.rethrowException(e); |
| } |
| } |
| |
| @SuppressWarnings("unchecked") |
| @Override |
| public <T> T callWithContext(Callable<T> callable) throws Exception { |
| Object owner = new Object(); |
| |
| Stack<ListenerInvocation> invocations = new Stack<ListenerInvocation>(); |
| boolean reentry = !ManagedContextUtils.setAndCheckOwner(owner); |
| Throwable firstError = null; |
| |
| try { |
| for (ManagedContextListener<?> listener : listeners) { |
| Object data = null; |
| |
| try { |
| data = listener.onEnterContext(reentry); |
| } catch (Throwable t) { |
| /* If one listener fails, still call all other listeners |
| * and then we will call onLeaveContext for all |
| */ |
| if (firstError == null) { |
| firstError = t; |
| } |
| logger.error("Failed onEnterContext for listener: " + listener, t); |
| } |
| |
| /* Stack data structure is used because in between onEnter and onLeave |
| * the listeners list could have changed |
| */ |
| invocations.push(new ListenerInvocation((ManagedContextListener<Object>)listener, data)); |
| } |
| |
| try { |
| if (firstError == null) { |
| /* Only call if all the listeners didn't blow up on onEnterContext */ |
| return callable.call(); |
| } else { |
| throwException(firstError); |
| return null; |
| } |
| } finally { |
| Throwable lastError = null; |
| |
| while (!invocations.isEmpty()) { |
| ListenerInvocation invocation = invocations.pop(); |
| try { |
| invocation.listener.onLeaveContext(invocation.data, reentry); |
| } catch (Throwable t) { |
| lastError = t; |
| logger.error("Failed onLeaveContext for listener: [" + invocation.listener + "]", t); |
| } |
| } |
| |
| if (firstError == null && lastError != null) { |
| throwException(lastError); |
| } |
| } |
| } finally { |
| if (ManagedContextUtils.clearOwner(owner)) |
| ManagedThreadLocal.reset(); |
| } |
| }; |
| |
| protected void throwException(Throwable t) throws Exception { |
| ManagedContextUtils.rethrowException(t); |
| if (t instanceof Exception) { |
| throw (Exception)t; |
| } |
| } |
| |
| public List<ManagedContextListener<?>> getListeners() { |
| return listeners; |
| } |
| |
| public void setListeners(List<ManagedContextListener<?>> listeners) { |
| this.listeners = new CopyOnWriteArrayList<ManagedContextListener<?>>(listeners); |
| } |
| |
| private static class ListenerInvocation { |
| ManagedContextListener<Object> listener; |
| Object data; |
| |
| public ListenerInvocation(ManagedContextListener<Object> listener, Object data) { |
| super(); |
| this.listener = listener; |
| this.data = data; |
| } |
| } |
| } |