Scale unique answer tracking

2026-07-13 02:11:54 -05:00
parent 700da4e415
commit f2c59388eb
23 changed files with 1064 additions and 131 deletions
@@ -0,0 +1,58 @@
+namespace QuestionsApi.Services;
+
+public sealed class AnswerStatisticsMaintenanceService : BackgroundService
+{
+    private readonly AnswerStatisticsStore _statistics;
+    private readonly QuestionAttemptStore _attempts;
+    private readonly ServiceMetrics _metrics;
+    private readonly ILogger<AnswerStatisticsMaintenanceService> _logger;
+    private readonly TimeSpan _interval;
+    private readonly string _owner = $"{Environment.MachineName}-{Guid.NewGuid():N}";
+
+    public AnswerStatisticsMaintenanceService(
+        AnswerStatisticsStore statistics,
+        QuestionAttemptStore attempts,
+        ServiceMetrics metrics,
+        IConfiguration configuration,
+        ILogger<AnswerStatisticsMaintenanceService> logger)
+    {
+        _statistics = statistics;
+        _attempts = attempts;
+        _metrics = metrics;
+        _logger = logger;
+        _interval = TimeSpan.FromSeconds(Math.Max(30, configuration.GetValue("AnswerStatistics:ReconcileSeconds", 300)));
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        try
+        {
+            if (await _statistics.TryAcquireBackfillLeaseAsync(_owner, TimeSpan.FromMinutes(30)))
+            {
+                _logger.LogInformation("Backfilling materialized answer statistics");
+                await _statistics.RebuildAllAsync();
+                await _statistics.MarkBackfillCompleteAsync(_owner);
+                _metrics.Reconciled();
+            }
+        }
+        catch (Exception exception)
+        {
+            _logger.LogError(exception, "Initial answer-statistics backfill failed");
+        }
+
+        using var timer = new PeriodicTimer(_interval);
+        while (await timer.WaitForNextTickAsync(stoppingToken))
+        {
+            try
+            {
+                var activeIds = await _attempts.GetActiveQuestionIdsAsync(DateTime.UtcNow.Subtract(_interval).Subtract(_interval));
+                await _statistics.RebuildQuestionsAsync(activeIds);
+                _metrics.Reconciled();
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Answer-statistics reconciliation failed");
+            }
+        }
+    }
+}