feat: DeadTokenCleanupWorker 구현 (#150)

Reviewed-on: https://git.ipstein.myds.me/SPMS/SPMS_API/pulls/151

SPMS.Infrastructure/DependencyInjection.cs

@@ -83,6 +83,7 @@ public static class DependencyInjection
         services.AddHostedService<PushWorker>();
         services.AddHostedService<ScheduleWorker>();
         services.AddHostedService<DailyStatWorker>();
+        services.AddHostedService<DeadTokenCleanupWorker>();
 
         // Token Store & Email Service
         services.AddMemoryCache();

SPMS.Infrastructure/Workers/DeadTokenCleanupWorker.cs

@@ -0,0 +1,139 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using SPMS.Domain.Entities;
+using SPMS.Infrastructure.Persistence;
+
+namespace SPMS.Infrastructure.Workers;
+
+public class DeadTokenCleanupWorker : BackgroundService
+{
+    private readonly IServiceScopeFactory _scopeFactory;
+    private readonly ILogger<DeadTokenCleanupWorker> _logger;
+
+    private static readonly TimeZoneInfo KstZone = TimeZoneInfo.FindSystemTimeZoneById("Asia/Seoul");
+    private const int BatchSize = 1000;
+    private const double SafetyThreshold = 0.5;
+
+    public DeadTokenCleanupWorker(
+        IServiceScopeFactory scopeFactory,
+        ILogger<DeadTokenCleanupWorker> logger)
+    {
+        _scopeFactory = scopeFactory;
+        _logger = logger;
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        _logger.LogInformation("DeadTokenCleanupWorker 시작");
+
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            var delay = CalculateDelayUntilNextSunday();
+            _logger.LogInformation("DeadTokenCleanupWorker 다음 실행까지 {Delay} 대기", delay);
+
+            try
+            {
+                await Task.Delay(delay, stoppingToken);
+            }
+            catch (TaskCanceledException)
+            {
+                break;
+            }
+
+            try
+            {
+                await CleanupAsync(stoppingToken);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "DeadTokenCleanupWorker 정리 중 오류 발생");
+            }
+        }
+    }
+
+    private TimeSpan CalculateDelayUntilNextSunday()
+    {
+        var nowKst = TimeZoneInfo.ConvertTimeFromUtc(DateTime.UtcNow, KstZone);
+        var daysUntilSunday = ((int)DayOfWeek.Sunday - (int)nowKst.DayOfWeek + 7) % 7;
+        var nextRun = nowKst.Date.AddDays(daysUntilSunday).AddHours(3);
+
+        if (nextRun <= nowKst)
+            nextRun = nextRun.AddDays(7);
+
+        return nextRun - nowKst;
+    }
+
+    private async Task CleanupAsync(CancellationToken stoppingToken)
+    {
+        using var scope = _scopeFactory.CreateScope();
+        var context = scope.ServiceProvider.GetRequiredService<AppDbContext>();
+
+        var cutoffUtc = DateTime.UtcNow.AddDays(-7);
+
+        var targetCount = await context.Set<Device>()
+            .CountAsync(d => !d.IsActive && d.UpdatedAt < cutoffUtc, stoppingToken);
+
+        var totalCount = await context.Set<Device>()
+            .CountAsync(stoppingToken);
+
+        _logger.LogInformation("DeadTokenCleanupWorker 삭제 대상: {TargetCount}개 / 전체: {TotalCount}개",
+            targetCount, totalCount);
+
+        if (targetCount == 0)
+        {
+            _logger.LogInformation("DeadTokenCleanupWorker 삭제 대상 없음");
+            await WriteSystemLogAsync(context, 0, stoppingToken);
+            return;
+        }
+
+        // 안전장치: 삭제 대상이 전체의 50% 초과 시 중단
+        if (totalCount > 0 && (double)targetCount / totalCount > SafetyThreshold)
+        {
+            _logger.LogWarning(
+                "DeadTokenCleanupWorker 안전 장치 발동! 삭제 대상({TargetCount})이 전체({TotalCount})의 50% 초과. 삭제를 중단합니다.",
+                targetCount, totalCount);
+            await WriteSystemLogAsync(context, 0, stoppingToken,
+                $"안전 장치 발동: 삭제 대상 {targetCount}개 / 전체 {totalCount}개 (50% 초과)");
+            return;
+        }
+
+        // 배치 삭제 (1000건씩, 트랜잭션 없음)
+        var totalDeleted = 0;
+        int deletedInBatch;
+
+        do
+        {
+            deletedInBatch = await context.Database.ExecuteSqlRawAsync(
+                "DELETE FROM Device WHERE is_active = false AND updated_at < {0} LIMIT 1000",
+                new object[] { cutoffUtc },
+                stoppingToken);
+
+            totalDeleted += deletedInBatch;
+
+            if (deletedInBatch > 0)
+                _logger.LogInformation("DeadTokenCleanupWorker 배치 삭제: {BatchCount}건 (누적: {TotalDeleted}건)",
+                    deletedInBatch, totalDeleted);
+        } while (deletedInBatch > 0 && !stoppingToken.IsCancellationRequested);
+
+        await WriteSystemLogAsync(context, totalDeleted, stoppingToken);
+
+        _logger.LogInformation("DeadTokenCleanupWorker 정리 완료: {TotalDeleted}건 삭제", totalDeleted);
+    }
+
+    private static async Task WriteSystemLogAsync(
+        AppDbContext context, int deletedCount,
+        CancellationToken stoppingToken, string? extraDetails = null)
+    {
+        var details = extraDetails ?? $"비활성 토큰 정리 완료: {deletedCount}건 삭제";
+
+        context.Set<SystemLog>().Add(new SystemLog
+        {
+            Action = "DeadTokenCleanup",
+            Details = details,
+            CreatedAt = DateTime.UtcNow
+        });
+        await context.SaveChangesAsync(stoppingToken);
+    }
+}