ServiceBase.cs

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/*
 * Copyright (c) Contributors, http://opensimulator.org/
 * See CONTRIBUTORS.TXT for a full list of copyright holders.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the OpenSimulator Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;
using System.IO;
using System.Collections.Generic;
using System.Reflection;
using log4net;
using Nini.Config;
using OpenSim.Services.Interfaces;

namespace OpenSim.Services.Base
{
    public class ServiceBase
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        
        public T LoadPlugin<T>(string dllName) where T:class
        {
            return LoadPlugin<T>(dllName, new Object[0]);
        }

        public T LoadPlugin<T>(string dllName, Object[] args) where T:class
        {
            // The path:type separator : is unfortunate because it collides
            // with Windows paths like C:\...
            // When the path provided includes the drive, this fails.
            // Hence the root/noroot thing going on here.
            string pathRoot = Path.GetPathRoot(dllName);
            string noRoot = dllName.Substring(pathRoot.Length);
            string[] parts = noRoot.Split(new char[] {':'});


            dllName = pathRoot + parts[0];

            string className = String.Empty;

            if (parts.Length > 1)
                className = parts[1];

            return LoadPlugin<T>(dllName, className, args);
        }

        public T LoadPlugin<T>(string dllName, string className, Object[] args) where T:class
        {
            string interfaceName = typeof(T).ToString();

            try
            {
                Assembly pluginAssembly = Assembly.LoadFrom(dllName);

//                m_log.DebugFormat("[SERVICE BASE]: Found assembly {0}", dllName);

                foreach (Type pluginType in pluginAssembly.GetTypes())
                {
//                    m_log.DebugFormat("[SERVICE BASE]: Found type {0}", pluginType);

                    if (pluginType.IsPublic)
                    {
                        if (className != String.Empty &&
                                pluginType.ToString() !=
                                pluginType.Namespace + "." + className)
                            continue;

                        Type typeInterface =
                                pluginType.GetInterface(interfaceName);
                        if (typeInterface != null)
                        {
                            T plug = (T)Activator.CreateInstance(pluginType,
                                    args);

                            return plug;
                        }
                    }
                }

                return null;
            }
            catch (Exception e)
            {
                List<string> strArgs = new List<string>();
                foreach (Object arg in args)
                    strArgs.Add(arg.ToString());
                
                m_log.Error(
                    string.Format(
                        "[SERVICE BASE]: Failed to load plugin {0} from {1} with args {2}", 
                        interfaceName, dllName, string.Join(", ", strArgs.ToArray())), e);
                
                return null;
            }
        }

        public ServiceBase(IConfigSource config)
        {
        }
    }
}