| /* |
| * 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.deploymentadmin.spi; |
| |
| import java.io.Closeable; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.ListIterator; |
| |
| import org.apache.felix.deploymentadmin.Constants; |
| import org.osgi.framework.Bundle; |
| import org.osgi.service.deploymentadmin.DeploymentException; |
| |
| /** |
| * Commands describe a group of tasks to be executed within the execution a |
| * deployment session. A command that has already executed can be rolled back |
| * and a command that is currently in progress can be signaled to stop it's |
| * activities by canceling it. |
| */ |
| public abstract class Command implements Constants { |
| |
| private final List m_rollback = new ArrayList(); |
| private final List m_commit = new ArrayList(); |
| |
| private volatile boolean m_cancelled; |
| |
| /** |
| * Executes the command, the specified <code>DeploymentSession</code> can be |
| * used to obtain various information about the deployment session which the |
| * command is part of. |
| * |
| * @param session The deployment session this command is part of. |
| * @throws DeploymentException Thrown if the command could not successfully |
| * execute. |
| */ |
| public final void execute(DeploymentSessionImpl session) throws DeploymentException { |
| try { |
| doExecute(session); |
| } |
| catch (Exception e) { |
| if (e instanceof DeploymentException) { |
| throw (DeploymentException) e; |
| } |
| throw new DeploymentException(CODE_OTHER_ERROR, "Command failed!", e); |
| } |
| } |
| |
| /** |
| * Executes the command, the specified <code>DeploymentSession</code> can be |
| * used to obtain various information about the deployment session which the |
| * command is part of. |
| * |
| * @param session The deployment session this command is part of. |
| * @throws Exception in case of this command could not terminate |
| * successfully. |
| */ |
| protected abstract void doExecute(DeploymentSessionImpl session) throws Exception; |
| |
| /** |
| * Rolls back all actions that were added through the |
| * <code>addRollback(Runnable r)</code> method (in reverse adding order). It |
| * is not guaranteed that the state of everything related to the command |
| * will be as if the command was never executed, a best effort should be |
| * made though. |
| * |
| * @param session the deployment session to rollback, should be used for |
| * logging purposes. |
| */ |
| protected void rollback(DeploymentSessionImpl session) { |
| try { |
| for (ListIterator i = m_rollback.listIterator(m_rollback.size()); i.hasPrevious();) { |
| Runnable runnable = (Runnable) i.previous(); |
| runnable.run(); |
| } |
| } |
| finally { |
| cleanUp(); |
| } |
| } |
| |
| /** |
| * Commits all changes the command may have defined when it was executed by |
| * calling the <code>execute()</code> method. |
| * |
| * @param session the deployment session to commit, should be used for |
| * logging purposes. |
| */ |
| protected final void commit(DeploymentSessionImpl session) { |
| try { |
| for (ListIterator i = m_commit.listIterator(); i.hasNext();) { |
| Runnable runnable = (Runnable) i.next(); |
| runnable.run(); |
| } |
| } |
| finally { |
| cleanUp(); |
| } |
| } |
| |
| private void cleanUp() { |
| m_rollback.clear(); |
| m_commit.clear(); |
| m_cancelled = false; |
| } |
| |
| /** |
| * Determines if the command was canceled. This method should be used |
| * regularly by implementing classes to determine if their command was |
| * canceled, if so they should return as soon as possible from their |
| * operations. |
| * |
| * @return true if the command was canceled, false otherwise. |
| */ |
| protected boolean isCancelled() { |
| return m_cancelled; |
| } |
| |
| /** |
| * Adds an action to be executed in case of a roll back. |
| * |
| * @param runnable The runnable to be executed in case of a roll back. |
| */ |
| protected void addRollback(AbstractAction runnable) { |
| m_rollback.add(runnable); |
| } |
| |
| /** |
| * Adds an action to be executed in case of a commit |
| * |
| * @param runnable The runnable to be executes in case of a commit. |
| */ |
| protected void addCommit(AbstractAction runnable) { |
| m_commit.add(runnable); |
| } |
| |
| /** |
| * Sets the command to being cancelled, this does not have an immediate |
| * effect. Commands that are executing should check regularly if they were |
| * cancelled and if so they should make an effort to stop their operations |
| * as soon as possible followed by throwing an |
| * <code>DeploymentException.CODE_CANCELLED</code> exception. |
| */ |
| public void cancel() { |
| m_cancelled = true; |
| } |
| |
| /** |
| * Determines whether a given bundle is actually a fragment bundle. |
| * |
| * @param bundle the bundle to test, cannot be <code>null</code>. |
| * @return <code>true</code> if the given bundle is actually a fragment |
| * bundle, <code>false</code> otherwise. |
| */ |
| static final boolean isFragmentBundle(Bundle bundle) { |
| Object fragmentHost = bundle.getHeaders().get(FRAGMENT_HOST); |
| return fragmentHost != null; |
| } |
| |
| static final void closeSilently(Closeable resource) { |
| if (resource != null) { |
| try { |
| resource.close(); |
| } |
| catch (IOException e) { |
| // Not much we can do... |
| } |
| } |
| } |
| } |