feat(browser): stream bounded live session updates (#26)

2026-07-16 23:25:48 +02:00
parent 95c3a4aed6
commit 06c4ecf8f3
34 changed files with 2249 additions and 27 deletions
@@ -1,4 +1,5 @@
 using System.Net;
+using System.Text.Json;
 using FinalFactory.Rendezvous.Contracts;
 using FinalFactory.Rendezvous.Server.Abuse;
 using FinalFactory.Rendezvous.Server.Browser;
@@ -69,6 +70,12 @@ internal static class ContractEndpoints
            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
            .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
            .WithName("BrowseSessions");
+        sessions.MapGet("/stream", StreamSessions)
+            .Produces<SessionStreamEvent>(StatusCodes.Status200OK, contentType: "text/event-stream")
+            .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
+            .WithName("StreamSessions");
        sessions.MapGet("/{listingId}", GetSession)
            .Produces<GetSessionResponse>()
            .Produces<ApiError>(StatusCodes.Status400BadRequest)
@@ -349,6 +356,123 @@ internal static class ContractEndpoints
        }
    }

+    private static async Task<IResult> StreamSessions(
+        [FromQuery] int contractVersion,
+        [FromQuery] string gameId,
+        [FromQuery] string environmentId,
+        [FromQuery] uint protocolVersion,
+        [FromQuery] string? regionId,
+        [FromQuery] bool? excludeFull,
+        [FromQuery] string? streamCursor,
+        [FromHeader(Name = "Last-Event-ID")] string? lastEventId,
+        [FromServices] SessionStreamService streams,
+        [FromServices] AbuseProtectionService abuseProtection,
+        HttpContext httpContext,
+        CancellationToken cancellationToken)
+    {
+        if (!GameId.TryParse(gameId, out GameId parsedGameId)
+            || !EnvironmentId.TryParse(environmentId, out EnvironmentId parsedEnvironmentId)
+            || regionId is not null && !RegionId.TryParse(regionId, out _))
+        {
+            return Error(RendezvousErrorCode.InvalidRequest);
+        }
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "StreamSessions",
+                Tenant(parsedGameId, parsedEnvironmentId),
+                null,
+                null,
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            BrowserServiceResult<SessionStreamSubscription> subscribed = streams.Subscribe(new()
+            {
+                ContractVersion = contractVersion,
+                GameId = parsedGameId,
+                EnvironmentId = parsedEnvironmentId,
+                ProtocolVersion = protocolVersion,
+                RegionId = regionId is null ? null : new RegionId(regionId),
+                ExcludeFull = excludeFull ?? false,
+            }, string.IsNullOrEmpty(lastEventId) ? streamCursor : lastEventId);
+            if (!subscribed.Succeeded || subscribed.Value is null)
+            {
+                return Error(subscribed.Error);
+            }
+
+            using SessionStreamSubscription subscription = subscribed.Value;
+            using CancellationTokenSource duration = CancellationTokenSource.CreateLinkedTokenSource(
+                cancellationToken);
+            duration.CancelAfter(streams.MaximumConnectionDuration);
+            HttpResponse response = httpContext.Response;
+            response.StatusCode = StatusCodes.Status200OK;
+            response.ContentType = "text/event-stream";
+            response.Headers.CacheControl = "no-cache, no-store";
+            response.Headers["X-Accel-Buffering"] = "no";
+            await response.StartAsync(duration.Token).ConfigureAwait(false);
+            try
+            {
+                while (!duration.IsCancellationRequested)
+                {
+                    SessionStreamReadResult read = streams.Read(subscription);
+                    if (read.RequiresReset)
+                    {
+                        await WriteSseAsync(response, streams.ResetEvent(subscription), duration.Token)
+                            .ConfigureAwait(false);
+                        await response.Body.FlushAsync(duration.Token).ConfigureAwait(false);
+                        break;
+                    }
+                    if (read.Events.Count > 0)
+                    {
+                        foreach (SessionStreamEvent item in read.Events)
+                        {
+                            await WriteSseAsync(response, item, duration.Token).ConfigureAwait(false);
+                        }
+                        await response.Body.FlushAsync(duration.Token).ConfigureAwait(false);
+                        continue;
+                    }
+
+                    bool changed = await streams.WaitForChangeAsync(subscription, duration.Token)
+                        .ConfigureAwait(false);
+                    if (!changed)
+                    {
+                        await WriteSseAsync(
+                            response,
+                            streams.KeepaliveEvent(subscription),
+                            duration.Token).ConfigureAwait(false);
+                        await response.Body.FlushAsync(duration.Token).ConfigureAwait(false);
+                    }
+                }
+            }
+            catch (OperationCanceledException) when (duration.IsCancellationRequested)
+            {
+            }
+            return Results.Empty;
+        }
+    }
+
+    private static async Task WriteSseAsync(
+        HttpResponse response,
+        SessionStreamEvent item,
+        CancellationToken cancellationToken)
+    {
+        string eventName = item.Kind switch
+        {
+            SessionStreamEventKind.SessionUpsert => "session_upsert",
+            SessionStreamEventKind.SessionRemove => "session_remove",
+            SessionStreamEventKind.Reset => "reset",
+            _ => "keepalive",
+        };
+        string data = JsonSerializer.Serialize(item, ContractJson.Options);
+        await response.WriteAsync(
+            $"id: {item.Cursor}\nevent: {eventName}\ndata: {data}\n\n",
+            cancellationToken).ConfigureAwait(false);
+    }
+
    private static IResult GetSession(
        SessionListingId listingId,
        [FromQuery] int contractVersion,