JiShe.CollectBus/src/JiShe.CollectBus.KafkaProducer/KafkaSubcribesExtensions.cs

using Confluent.Kafka;
using JiShe.CollectBus.Kafka.AdminClient;
using JiShe.CollectBus.Kafka.Attributes;
using JiShe.CollectBus.Kafka.Consumer;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System.Reflection;

namespace JiShe.CollectBus.Kafka
{
    public static class KafkaSubcribesExtensions
    {
        /// <summary>
        /// 添加Kafka订阅
        /// </summary>
        /// <param name="app"></param>
        /// <param name="assembly"></param>
        public static void UseKafkaSubscribers(this IApplicationBuilder app, Assembly[] assemblys)
        {
            var provider = app.ApplicationServices;
            var lifetime = provider.GetRequiredService<IHostApplicationLifetime>();

            lifetime.ApplicationStarted.Register(() =>
            {
                var logger = provider.GetRequiredService<ILogger<CollectBusKafkaModule>>();
                int threadCount = 0;
                int topicCount = 0;
                foreach (Assembly assembly in assemblys)
                {
                    var subscribeTypes = assembly.GetTypes()
                       .Where(t => typeof(IKafkaSubscribe).IsAssignableFrom(t))
                       .ToList();

                    if (subscribeTypes.Count == 0) return;
                    foreach (var subscribeType in subscribeTypes)
                    {
                        var subscribes = provider.GetServices(subscribeType).ToList();
                        subscribes.ForEach(subscribe => {

                            if (subscribe is IKafkaSubscribe)
                            {
                                Tuple<int, int> tuple = BuildKafkaSubscriber(subscribe, provider, logger);
                                threadCount += tuple.Item1;
                                topicCount += tuple.Item2;
                            }
                        });
                    }
                }
                logger.LogInformation($"kafka订阅主题:{topicCount}数,共启动:{threadCount}线程");
            });
        }

        /// <summary>
        /// 构建Kafka订阅
        /// </summary>
        /// <param name="subscribe"></param>
        /// <param name="provider"></param>
        private static Tuple<int,int> BuildKafkaSubscriber(object subscribe, IServiceProvider provider,ILogger<CollectBusKafkaModule> logger)
        {
            var subscribedMethods = subscribe.GetType().GetMethods()
              .Select(m => new { Method = m, Attribute = m.GetCustomAttribute<KafkaSubscribeAttribute>() })
              .Where(x => x.Attribute != null)
              .ToArray();

            int threadCount = 0;
            foreach (var sub in subscribedMethods)
            {
                var adminClientService = provider.GetRequiredService<IAdminClientService>();
                int partitionCount = sub.Attribute!.TaskCount==-1?adminClientService.GetTopicPartitionsNum(sub.Attribute!.Topic) : sub.Attribute!.TaskCount;
                if (partitionCount <= 0)
                    partitionCount = 1;
                for (int i = 0; i < partitionCount; i++)
                {
                    Task.Run(() => StartConsumerAsync(provider, sub.Attribute!, sub.Method, subscribe, logger));
                    threadCount++;
                }
            }
            return Tuple.Create(threadCount, subscribedMethods.Length);
        }

        /// <summary>
        /// 启动后台消费线程
        /// </summary>
        /// <param name="config"></param>
        /// <param name="attr"></param>
        /// <param name="method"></param>
        /// <param name="consumerInstance"></param>
        /// <returns></returns>
        private static async Task StartConsumerAsync(IServiceProvider provider, KafkaSubscribeAttribute attr,MethodInfo method, object subscribe, ILogger<CollectBusKafkaModule> logger)
        {
            var consumerService = provider.GetRequiredService<IConsumerService>();
           
            await consumerService.SubscribeAsync<dynamic>(attr.Topic, async (message) =>
            {
                try
                {
                    // 处理消息
                    return await ProcessMessageAsync(message, method, subscribe);
                }
                catch (ConsumeException ex)
                {
                    // 处理消费错误
                    logger.LogError($"kafka消费异常:{ex.Message}");
                }
                return await Task.FromResult(false);
            });
        }


        /// <summary>
        /// 处理消息
        /// </summary>
        /// <param name="message"></param>
        /// <param name="method"></param>
        /// <param name="subscribe"></param>
        /// <returns></returns>
        private static async Task<bool> ProcessMessageAsync(dynamic message, MethodInfo method, object subscribe)
        {
            var parameters = method.GetParameters();
            bool isGenericTask = method.ReturnType.IsGenericType
                  && method.ReturnType.GetGenericTypeDefinition() == typeof(Task<>);
            bool existParameters = parameters.Length > 0;
            //dynamic? messageObj= null;
            //if (existParameters)
            //{
            //     var paramType = parameters[0].ParameterType;
            //     messageObj = paramType == typeof(string) ? message : message.Deserialize(paramType);
            //}
            if (isGenericTask)
            {
                object? result = await (Task<ISubscribeAck>)method.Invoke(subscribe, existParameters? new[] { message } :null)!;
                if (result is ISubscribeAck ackResult)
                {
                    return ackResult.Ack;
                }
            }
            else
            {
                object? result = method.Invoke(subscribe, existParameters ? new[] { message } : null);
                if (result is ISubscribeAck ackResult)
                {
                    return ackResult.Ack;
                }
            }
            return false;
        }

    }
}