140 lines
5.2 KiB
C#
140 lines
5.2 KiB
C#
using LiveForum.IService.Messages;
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using LiveForum.Model.Events;
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using Microsoft.Extensions.Hosting;
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using Microsoft.Extensions.Logging;
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using StackExchange.Redis;
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using System;
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using System.Text.Json;
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using System.Threading;
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using System.Threading.Tasks;
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namespace LiveForum.WebApi.BackgroundServices
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{
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/// <summary>
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/// 评论回复消息后台消费者
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/// 从 message:events:comment 队列消费评论回复事件
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/// </summary>
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public class CommentReplyMessageConsumer : BackgroundService
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{
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private readonly IDatabase _database;
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private readonly IMessageEventHandler _eventHandler;
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private readonly ILogger<CommentReplyMessageConsumer> _logger;
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private const string QUEUE_NAME = "message:events:comment";
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public CommentReplyMessageConsumer(
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IDatabase database,
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IMessageEventHandler eventHandler,
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ILogger<CommentReplyMessageConsumer> logger)
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{
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_database = database;
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_eventHandler = eventHandler;
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_logger = logger;
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}
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protected override async Task ExecuteAsync(CancellationToken stoppingToken)
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{
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_logger.LogInformation("[CommentConsumer] 评论回复消息消费者已启动");
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while (!stoppingToken.IsCancellationRequested)
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{
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try
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{
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// 从Redis List左侧阻塞弹出（BLPOP，超时5秒）
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var result = await _database.ListLeftPopAsync(QUEUE_NAME);
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if (result.HasValue)
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{
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var json = result.ToString();
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// 反序列化事件
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var evt = JsonSerializer.Deserialize<CommentReplyEvent>(json, new JsonSerializerOptions
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{
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PropertyNameCaseInsensitive = true
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});
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if (evt != null)
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{
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_logger.LogInformation(
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"[CommentConsumer] 开始处理评论回复事件: EventId={EventId}, CommentId={CommentId}, IsDirectComment={IsDirectComment}",
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evt.EventId, evt.CommentId, evt.IsDirectComment);
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// 处理事件（带重试）
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await ProcessWithRetryAsync(evt, stoppingToken);
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}
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}
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else
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{
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// 队列为空，等待1秒再查询
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await Task.Delay(1000, stoppingToken);
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}
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}
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catch (OperationCanceledException)
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{
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// 正常停止
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break;
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "[CommentConsumer] 消费评论回复事件时发生异常");
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// 发生异常后等待5秒再继续
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await Task.Delay(5000, stoppingToken);
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}
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}
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_logger.LogInformation("[CommentConsumer] 评论回复消息消费者已停止");
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}
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/// <summary>
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/// 带重试的事件处理
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/// </summary>
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private async Task ProcessWithRetryAsync(CommentReplyEvent evt, CancellationToken stoppingToken)
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{
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const int maxRetries = 3;
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var retryCount = 0;
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while (retryCount < maxRetries && !stoppingToken.IsCancellationRequested)
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{
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try
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{
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await _eventHandler.HandleCommentReplyEventAsync(evt);
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_logger.LogInformation(
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"[CommentConsumer] 评论回复事件处理成功: EventId={EventId}",
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evt.EventId);
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return; // 成功，退出重试循环
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}
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catch (Exception ex)
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{
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retryCount++;
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if (retryCount >= maxRetries)
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{
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_logger.LogError(ex,
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"[CommentConsumer] 评论回复事件处理失败（已重试{RetryCount}次）: EventId={EventId}",
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retryCount, evt.EventId);
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// TODO: 可以将失败的事件写入死信队列或日志表
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return;
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}
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_logger.LogWarning(ex,
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"[CommentConsumer] 评论回复事件处理失败，准备重试({RetryCount}/{MaxRetries}): EventId={EventId}",
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retryCount, maxRetries, evt.EventId);
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// 延迟后重试（指数退避）
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await Task.Delay(1000 * retryCount, stoppingToken);
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}
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}
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}
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public override Task StopAsync(CancellationToken cancellationToken)
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{
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_logger.LogInformation("[CommentConsumer] 正在停止评论回复消息消费者...");
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return base.StopAsync(cancellationToken);
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}
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}
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}
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