MessageTypeRegistry.cs

using Microsoft.Extensions.Logging;
using System;
using System.Reflection;
using System.Threading;

namespace Uml.Robotics.Ros
{
    public class MessageTypeRegistry
        : TypeRegistryBase
    {
        private static Lazy<MessageTypeRegistry> defaultInstance = new Lazy<MessageTypeRegistry>(LazyThreadSafetyMode.ExecutionAndPublication);

        public static MessageTypeRegistry Default
        {
            get { return defaultInstance.Value; }
        }

        public MessageTypeRegistry()
            : base(ApplicationLogging.CreateLogger<MessageTypeRegistry>())
        {
        }

        public RosMessage CreateMessage(string rosMessageType)
        {
            return base.Create<RosMessage>(rosMessageType);
        }

        public void ParseAssemblyAndRegisterRosMessages(Assembly assembly)
        {
            foreach (Type othertype in assembly.GetTypes())
            {
                var messageInfo = othertype.GetTypeInfo();
                if (othertype == typeof(RosMessage) || !messageInfo.IsSubclassOf(typeof(RosMessage)) || othertype == typeof(InnerActionMessage))
                {
                    continue;
                }

                var goalAttribute = messageInfo.GetCustomAttribute<ActionGoalMessageAttribute>();
                var resultAttribute = messageInfo.GetCustomAttribute<ActionResultMessageAttribute>();
                var feedbackAttribute = messageInfo.GetCustomAttribute<ActionFeedbackMessageAttribute>();
                var ignoreAttribute = messageInfo.GetCustomAttribute<IgnoreRosMessageAttribute>();
                RosMessage message;
                if (goalAttribute != null || resultAttribute != null || feedbackAttribute != null || ignoreAttribute != null)
                {
                    Type actionType;
                    if (goalAttribute != null)
                    {
                        actionType = typeof(GoalActionMessage<>);
                    }
                    else if (resultAttribute != null)
                    {
                        actionType = typeof(ResultActionMessage<>);
                    }
                    else if (feedbackAttribute != null)
                    {
                        actionType = typeof(FeedbackActionMessage<>);
                    }
                    else if (ignoreAttribute != null)
                    {
                        continue;
                    }
                    else
                    {
                        throw new InvalidOperationException($"Could create Action Message for {othertype}");
                    }

                    Type[] innerType = { othertype };
                    var goalMessageType = actionType.MakeGenericType(innerType);
                    message = (Activator.CreateInstance(goalMessageType)) as RosMessage;
                }
                else
                {
                    message = Activator.CreateInstance(othertype) as RosMessage;
                    if ((message != null) && (message.MessageType == "undefined/unknown"))
                    {
                        throw new Exception("Invalid message type. Message type field (msgtype) was not initialized correctly.");
                    }
                }

                var packageName = message.MessageType.Split('/')[0];
                if (!PackageNames.Contains(packageName))
                {
                    PackageNames.Add(packageName);
                }

                Logger.LogDebug($"Register {message.MessageType}");
                if (!TypeRegistry.ContainsKey(message.MessageType))
                {
                    TypeRegistry.Add(message.MessageType, message.GetType());
                }
                else
                {
                    var messageFromRegistry = CreateMessage(message.MessageType);
                    if (messageFromRegistry.MD5Sum() != message.MD5Sum())
                    {
                        throw new InvalidOperationException($"The message of type {message.MessageType} has already been " +
                            $"registered and the MD5 sums do not match. Already registered: {messageFromRegistry.MD5Sum()} " +
                            $"new message: {message.MD5Sum()}.");
                    } else
                    {
                        Logger.LogDebug($"The message of type {message.MessageType} has already been registered. Since the" +
                            "MD5 sums do match, the new message is ignored.");
                    }
                }
            }
        }


        public static void Reset()
        {
            defaultInstance = new Lazy<MessageTypeRegistry>(LazyThreadSafetyMode.ExecutionAndPublication);
        }
    }
}