feature: Ward Gateway Service (Local-First Clinical Path)

2026-06-23 16:45:38 +08:00
parent d8e142fffe
commit 1bf8359097
100 changed files with 5474 additions and 4 deletions
@@ -0,0 +1,94 @@
+using System.Text.Json;
+using Microsoft.EntityFrameworkCore;
+using StackExchange.Redis;
+
+public class ThresholdCacheLoader : IHostedService
+{
+    private readonly IServiceProvider _services;
+    private readonly IConnectionMultiplexer _redis;
+    private readonly ILogger<ThresholdCacheLoader> _logger;
+
+    public ThresholdCacheLoader(
+        IServiceProvider services,
+        IConnectionMultiplexer redis,
+        ILogger<ThresholdCacheLoader> logger)
+    {
+        _services = services;
+        _redis = redis;
+        _logger = logger;
+    }
+
+    public async Task StartAsync(CancellationToken cancellationToken)
+    {
+        using var scope = _services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<GatewayDbContext>();
+        await RefreshAsync(db, _redis, _logger, cancellationToken);
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
+    /// <summary>
+    /// Reloads all gateway alert thresholds into Redis. Called on startup and after
+    /// <see cref="EncounterReplicaSyncService"/> pulls thresholds from central.
+    /// </summary>
+    public static async Task RefreshAsync(
+        GatewayDbContext db,
+        IConnectionMultiplexer redis,
+        ILogger logger,
+        CancellationToken cancellationToken = default)
+    {
+        var thresholds = await db.AlertThresholds.ToListAsync(cancellationToken);
+        if (thresholds.Count == 0)
+        {
+            logger.LogWarning("No alert thresholds in gateway DB — Redis cache not updated");
+            return;
+        }
+
+        const int maxAttempts = 3;
+        int[] backoffMs = [2000, 4000, 8000];
+
+        for (var attempt = 0; attempt < maxAttempts; attempt++)
+        {
+            try
+            {
+                WriteThresholds(redis, thresholds);
+                logger.LogInformation(
+                    "Loaded {Count} alert thresholds into gateway Redis cache", thresholds.Count);
+                return;
+            }
+            catch (RedisException ex)
+            {
+                logger.LogWarning(ex,
+                    "Redis unavailable during gateway threshold cache load — attempt {Attempt}/{Max}",
+                    attempt + 1, maxAttempts);
+
+                if (attempt < maxAttempts - 1)
+                    await Task.Delay(backoffMs[attempt], cancellationToken);
+            }
+        }
+
+        logger.LogError(
+            "Failed to load thresholds into gateway Redis after {Max} attempts — " +
+            "observation ingest falls back to PostgreSQL for threshold lookups",
+            maxAttempts);
+    }
+
+    private static void WriteThresholds(IConnectionMultiplexer redis, List<ReplicaAlertThreshold> thresholds)
+    {
+        var cache = redis.GetDatabase();
+        var batch = cache.CreateBatch();
+
+        foreach (var t in thresholds)
+        {
+            var json = JsonSerializer.Serialize(new ThresholdCacheEntry(
+                t.ObservationCode,
+                t.CriticalLow,
+                t.WarningLow,
+                t.WarningHigh,
+                t.CriticalHigh));
+            _ = batch.StringSetAsync($"threshold:{t.ObservationCode}", json);
+        }
+
+        batch.Execute();
+    }
+}