251 lines
9.3 KiB
C#
251 lines
9.3 KiB
C#
using FreeSql;
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using LiveForum.Code.Base;
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using LiveForum.Code.Redis.Contract;
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using LiveForum.Model;
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using Microsoft.Extensions.Hosting;
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using Microsoft.Extensions.Logging;
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using System;
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using System.Collections.Generic;
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using System.Linq;
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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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/// 浏览批量同步后台服务
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/// 从Redis Hash获取待处理操作，定时批量同步到数据库
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/// 触发条件：每2分钟执行一次
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/// </summary>
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public class ViewBatchSyncService : BackgroundService
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{
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private readonly IRedisService _redisService;
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private readonly IFreeSql _fsql;
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private readonly ILogger<ViewBatchSyncService> _logger;
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private const string VIEW_PENDING_OPERATIONS_KEY = "view:pending:operations";
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private static readonly TimeSpan SYNC_INTERVAL = TimeSpan.FromSeconds(30); // 缩短间隔
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private const int MAX_BATCH_SIZE = 100; // 限制批次大小
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public ViewBatchSyncService(
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IRedisService redisService,
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IFreeSql fsql,
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ILogger<ViewBatchSyncService> logger)
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{
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_redisService = redisService;
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_fsql = fsql;
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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("[ViewBatchSync] 浏览批量同步服务已启动");
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while (!stoppingToken.IsCancellationRequested)
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{
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try
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{
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// 等待同步间隔
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await Task.Delay(SYNC_INTERVAL, stoppingToken);
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_logger.LogDebug("[ViewBatchSync] 开始定时批量同步");
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await ProcessBatchSyncAsync(stoppingToken);
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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, "[ViewBatchSync] 批量同步过程中发生异常");
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// 发生异常后等待30秒再继续
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await Task.Delay(TimeSpan.FromSeconds(30), stoppingToken);
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}
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}
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_logger.LogInformation("[ViewBatchSync] 浏览批量同步服务已停止");
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}
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/// <summary>
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/// 执行批量同步
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/// </summary>
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private async Task ProcessBatchSyncAsync(CancellationToken stoppingToken)
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{
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try
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{
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// 1. 限量获取待处理操作，避免一次性处理过多数据
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var (viewCountsByPostId, processedFields) = await GetLimitedOperationsAsync();
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if (viewCountsByPostId.Count == 0)
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{
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_logger.LogDebug("[ViewBatchSync] 没有待处理的浏览操作");
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return;
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}
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_logger.LogInformation("[ViewBatchSync] 本次处理 {Count} 个帖子的浏览更新", viewCountsByPostId.Count);
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// 2. 批量更新数据库
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await ProcessDatabaseOperationsAsync(viewCountsByPostId, stoppingToken);
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// 3. 清除已处理的待处理记录
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if (processedFields.Count > 0)
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{
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foreach (var field in processedFields)
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{
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await _redisService.HashDeleteAsync(VIEW_PENDING_OPERATIONS_KEY, field);
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}
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_logger.LogInformation("[ViewBatchSync] 已清除 {Count} 个已处理的操作记录", processedFields.Count);
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}
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_logger.LogInformation("[ViewBatchSync] 批量同步完成。更新了 {Count} 个帖子的浏览次数", viewCountsByPostId.Count);
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "[ViewBatchSync] 批量同步处理失败");
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throw;
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}
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}
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/// <summary>
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/// 限量获取Redis中的操作，避免一次性处理过多
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/// </summary>
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private async Task<(Dictionary<long, int> viewCountsByPostId, List<string> processedFields)> GetLimitedOperationsAsync()
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{
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var viewCountsByPostId = new Dictionary<long, int>();
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var processedFields = new List<string>();
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var processedCount = 0;
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// 获取所有操作，但限制处理数量
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var allOperations = await _redisService.HashGetAllAsync(VIEW_PENDING_OPERATIONS_KEY);
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if (allOperations == null || allOperations.Length == 0)
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{
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return (viewCountsByPostId, processedFields);
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}
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foreach (var entry in allOperations)
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{
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if (processedCount >= MAX_BATCH_SIZE)
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break;
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var field = entry.Name.ToString(); // {userId}:{postId}
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var value = entry.Value.ToString();
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try
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{
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var parts = field.Split(':');
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if (parts.Length != 2)
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{
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_logger.LogWarning("[ViewBatchSync] 无效的操作字段格式: {Field}", field);
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continue;
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}
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if (!long.TryParse(parts[0], out var userId) ||
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!long.TryParse(parts[1], out var postId))
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{
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_logger.LogWarning("[ViewBatchSync] 解析操作字段失败: {Field}", field);
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continue;
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}
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processedFields.Add(field);
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// 按postId分组，统计每个帖子需要增加的浏览次数
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if (viewCountsByPostId.ContainsKey(postId))
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{
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viewCountsByPostId[postId]++;
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}
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else
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{
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viewCountsByPostId[postId] = 1;
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}
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processedCount++;
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}
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catch (Exception ex)
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{
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_logger.LogWarning(ex, "[ViewBatchSync] 解析操作失败。Field: {Field}, Value: {Value}",
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field, value);
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}
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}
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return (viewCountsByPostId, processedFields);
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}
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/// <summary>
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/// 处理数据库操作
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/// </summary>
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private async Task ProcessDatabaseOperationsAsync(
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Dictionary<long, int> viewCountsByPostId,
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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)
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{
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try
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{
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// 使用单条SQL批量更新，避免逐条操作
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var updateCases = viewCountsByPostId
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.OrderBy(kvp => kvp.Key) // 统一顺序，避免死锁
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.Select(kvp => $"WHEN {kvp.Key} THEN ViewCount + {kvp.Value}")
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.ToList();
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if (updateCases.Any())
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{
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var postIds = string.Join(",", viewCountsByPostId.Keys.OrderBy(x => x));
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var sql = $@"
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UPDATE T_Posts WITH (UPDLOCK, READPAST, ROWLOCK)
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SET ViewCount = CASE Id
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{string.Join(" ", updateCases)}
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ELSE ViewCount
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END
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WHERE Id IN ({postIds})";
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var affectedRows = await _fsql.Ado.ExecuteNonQueryAsync(sql);
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_logger.LogInformation("[ViewBatchSync] 成功更新了 {Count} 个帖子的浏览次数，影响 {Rows} 行",
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viewCountsByPostId.Count, affectedRows);
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}
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return; // 成功则退出重试循环
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}
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catch (Exception ex) when (IsDeadlockException(ex) && retryCount < maxRetries - 1)
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{
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retryCount++;
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var delay = TimeSpan.FromMilliseconds(100 * Math.Pow(2, retryCount));
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_logger.LogWarning(ex, "[ViewBatchSync] 检测到死锁，第 {Retry} 次重试，延迟 {Delay}ms",
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retryCount, delay.TotalMilliseconds);
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await Task.Delay(delay, stoppingToken);
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "[ViewBatchSync] 处理数据库操作时发生异常");
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throw;
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}
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}
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}
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private bool IsDeadlockException(Exception ex)
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{
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return ex.Message.Contains("deadlock") ||
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ex.Message.Contains("deadlocked") ||
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ex.Message.Contains("was chosen as the deadlock victim");
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}
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public override Task StopAsync(CancellationToken cancellationToken)
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{
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_logger.LogInformation("[ViewBatchSync] 正在停止浏览批量同步服务...");
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return base.StopAsync(cancellationToken);
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}
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}
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}
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