| | | 1 | | using Microsoft.Extensions.Hosting; |
| | | 2 | | using Microsoft.Extensions.Logging; |
| | | 3 | | using Microsoft.Extensions.Options; |
| | | 4 | | using System.Threading.Channels; |
| | | 5 | | |
| | | 6 | | namespace AsyncResponse.Transports.MongoDB; |
| | | 7 | | |
| | | 8 | | /// <summary> |
| | | 9 | | /// Base hosted service that consumes one MongoDB queue and routes documents to AsyncResponse ingress |
| | | 10 | | /// with configured acknowledgement, redelivery, and dead-letter behavior. |
| | | 11 | | /// </summary> |
| | | 12 | | internal abstract class MongoDbSubscriberService : BackgroundService |
| | | 13 | | { |
| | | 14 | | private readonly MongoDbTransportStore _store; |
| | | 15 | | private readonly Channel<bool> _signals = Channel.CreateBounded<bool>(new BoundedChannelOptions(1) |
| | | 16 | | { |
| | | 17 | | SingleReader = true, |
| | | 18 | | SingleWriter = false, |
| | | 19 | | FullMode = BoundedChannelFullMode.DropWrite |
| | | 20 | | }); |
| | | 21 | | |
| | | 22 | | protected MongoDbSubscriberService( |
| | | 23 | | IOptions<MongoDbAsyncResponseTransportOptions> options, |
| | | 24 | | MongoDbTransportStore store, |
| | | 25 | | ILogger logger) |
| | | 26 | | { |
| | | 27 | | Options = options.Value; |
| | | 28 | | MongoDbTransportOptionsValidator.ValidateCommon(Options); |
| | | 29 | | _store = store; |
| | | 30 | | Logger = logger; |
| | | 31 | | } |
| | | 32 | | |
| | | 33 | | protected MongoDbAsyncResponseTransportOptions Options { get; } |
| | | 34 | | protected ILogger Logger { get; } |
| | | 35 | | |
| | | 36 | | protected abstract string Queue { get; } |
| | | 37 | | protected abstract MongoDbSubscriberOptions SubscriberOptions { get; } |
| | | 38 | | protected abstract MongoDbSubscriberRole Role { get; } |
| | | 39 | | protected abstract Task HandleMessageAsync(MongoDbTransportDelivery delivery, CancellationToken cancellationToken); |
| | | 40 | | |
| | | 41 | | /// <inheritdoc /> |
| | | 42 | | /// <summary> |
| | | 43 | | /// Validates subscriber options here rather than at the top of <c>ExecuteAsync</c>: since |
| | | 44 | | /// Microsoft.Extensions.Hosting.Abstractions 10.0.10, <c>BackgroundService.StartAsync</c> no |
| | | 45 | | /// longer runs <c>ExecuteAsync</c> inline, so a throw there surfaces only through the host's |
| | | 46 | | /// background-exception handling — or never, when a fast stop discards the queued work — |
| | | 47 | | /// instead of failing host startup synchronously. |
| | | 48 | | /// </summary> |
| | | 49 | | public override Task StartAsync(CancellationToken cancellationToken) |
| | | 50 | | { |
| | | 51 | | MongoDbTransportOptionsValidator.ValidateSubscriber(Options, SubscriberOptions, Role.ToString()); |
| | | 52 | | return base.StartAsync(cancellationToken); |
| | | 53 | | } |
| | | 54 | | |
| | | 55 | | protected override async Task ExecuteAsync(CancellationToken stoppingToken) |
| | | 56 | | { |
| | | 57 | | // ONE dispatcher for the service's lifetime, outliving every supervised attempt below; only |
| | | 58 | | // the host stopping disposes it. In early-ACK mode it owns the queued and running work |
| | | 59 | | // whose queue items the ACK already deleted, and its DisposeAsync IS the stop-time drain: |
| | | 60 | | // wait out BackgroundDrainTimeout, then cancel and dead-letter whatever is still queued. |
| | | 61 | | // Built inside the attempt, every poll fault — a claim timeout, a deadlock victim, a |
| | | 62 | | // failover: routine for a loop that polls the database several times a second — ran that |
| | | 63 | | // drain on a host that was NOT stopping: consumption paused for the whole budget, then |
| | | 64 | | // healthy already-ACKed work was dead-lettered as "drain budget lapsed" — or, when the |
| | | 65 | | // dead-letter write needed the same failing database, survived only as an Error log line. |
| | | 66 | | await using var dispatcher = new MongoDbMessageDispatcher( |
| | | 67 | | HandleMessageAsync, |
| | | 68 | | Options, |
| | | 69 | | SubscriberOptions, |
| | | 70 | | Logger, |
| | | 71 | | Role); |
| | | 72 | | |
| | | 73 | | await SubscriberSupervisor.RunAsync( |
| | | 74 | | attemptToken => RunSubscriberAsync(dispatcher, attemptToken), |
| | | 75 | | stoppingToken, |
| | | 76 | | failures => AsyncResponseRetry.Backoff(failures, Options.SubscriberRetryBaseDelay, Options.SubscriberRetryMa |
| | | 77 | | (ex, delay) => Logger.LogWarning(ex, "MongoDB subscriber failed for queue {Queue} ({Role}); retrying in {Ret |
| | | 78 | | } |
| | | 79 | | |
| | | 80 | | private async Task RunSubscriberAsync(MongoDbMessageDispatcher dispatcher, CancellationToken stoppingToken) |
| | | 81 | | { |
| | | 82 | | await _store.EnsureCreatedAsync(stoppingToken).ConfigureAwait(false); |
| | | 83 | | using var signalCts = CancellationTokenSource.CreateLinkedTokenSource(stoppingToken); |
| | | 84 | | |
| | | 85 | | // The wake task starts inside the try so ANY escape — a throwing logger provider |
| | | 86 | | // included — runs the cancelling finally. Disposing signalCts does NOT cancel it, so an |
| | | 87 | | // escape before the finally would otherwise leave ListenLoopAsync parked on the change |
| | | 88 | | // stream, leaking a cursor per retry. |
| | | 89 | | Task? listenTask = null; |
| | | 90 | | try |
| | | 91 | | { |
| | | 92 | | listenTask = Options.UseChangeStreamWake |
| | | 93 | | ? Task.Run(() => ListenLoopAsync(signalCts.Token), signalCts.Token) |
| | | 94 | | : Task.CompletedTask; |
| | | 95 | | |
| | | 96 | | Logger.LogInformation( |
| | | 97 | | "MongoDB subscriber started. Queue: {Queue}. Role: {Role}. AckMode: {AckMode}.", |
| | | 98 | | Queue, |
| | | 99 | | Role, |
| | | 100 | | SubscriberOptions.AckMode); |
| | | 101 | | |
| | | 102 | | while (!stoppingToken.IsCancellationRequested) |
| | | 103 | | { |
| | | 104 | | var claimed = 0; |
| | | 105 | | await foreach (var delivery in _store.ClaimBatchAsync(Queue, SubscriberOptions.BatchSize, Options.LockTi |
| | | 106 | | { |
| | | 107 | | claimed++; |
| | | 108 | | await dispatcher.HandleAsync(delivery, stoppingToken).ConfigureAwait(false); |
| | | 109 | | } |
| | | 110 | | |
| | | 111 | | if (claimed > 0) |
| | | 112 | | continue; |
| | | 113 | | |
| | | 114 | | await WaitForSignalOrDelayAsync(stoppingToken).ConfigureAwait(false); |
| | | 115 | | } |
| | | 116 | | } |
| | | 117 | | finally |
| | | 118 | | { |
| | | 119 | | await signalCts.CancelAsync().ConfigureAwait(false); |
| | | 120 | | if (listenTask is not null) |
| | | 121 | | { |
| | | 122 | | try |
| | | 123 | | { |
| | | 124 | | await listenTask.WaitAsync(Options.ShutdownTimeout).ConfigureAwait(false); |
| | | 125 | | } |
| | | 126 | | catch (Exception ex) when (ex is OperationCanceledException or TimeoutException) |
| | | 127 | | { |
| | | 128 | | } |
| | | 129 | | } |
| | | 130 | | } |
| | | 131 | | } |
| | | 132 | | |
| | | 133 | | private async Task ListenLoopAsync(CancellationToken cancellationToken) |
| | | 134 | | { |
| | | 135 | | // Retry with backoff, mirroring the channel-side listener: a transient watch failure |
| | | 136 | | // (network blip, replica-set stepdown) must not permanently degrade this subscriber from |
| | | 137 | | // push wake to poll-only latency for the rest of the process's uptime. |
| | | 138 | | var failures = 0; |
| | | 139 | | while (!cancellationToken.IsCancellationRequested) |
| | | 140 | | { |
| | | 141 | | try |
| | | 142 | | { |
| | | 143 | | await _store.WatchQueueAsync(Queue, () => |
| | | 144 | | { |
| | | 145 | | _signals.Writer.TryWrite(true); |
| | | 146 | | return Task.CompletedTask; |
| | | 147 | | }, cancellationToken).ConfigureAwait(false); |
| | | 148 | | failures = 0; |
| | | 149 | | } |
| | | 150 | | catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested) |
| | | 151 | | { |
| | | 152 | | return; |
| | | 153 | | } |
| | | 154 | | catch (Exception ex) when (MongoDbTransportStore.IsChangeStreamUnsupported(ex)) |
| | | 155 | | { |
| | | 156 | | // Structural, not transient: a standalone server never grows change streams, so |
| | | 157 | | // retrying is pointless — the poll loop is the permanent delivery path here. |
| | | 158 | | Logger.LogInformation( |
| | | 159 | | "MongoDB change streams are unavailable for queue {Queue} (the server is not a replica set); polling |
| | | 160 | | Queue, |
| | | 161 | | SubscriberOptions.EmptyPollDelay); |
| | | 162 | | return; |
| | | 163 | | } |
| | | 164 | | catch (Exception ex) |
| | | 165 | | { |
| | | 166 | | failures++; |
| | | 167 | | var delay = AsyncResponseRetry.Backoff(failures, Options.SubscriberRetryBaseDelay, Options.SubscriberRet |
| | | 168 | | Logger.LogWarning(ex, "MongoDB change-stream wake for queue {Queue} failed; retrying in {RetryDelay} (po |
| | | 169 | | try |
| | | 170 | | { |
| | | 171 | | await Task.Delay(delay, cancellationToken).ConfigureAwait(false); |
| | | 172 | | } |
| | | 173 | | catch (OperationCanceledException) |
| | | 174 | | { |
| | | 175 | | return; |
| | | 176 | | } |
| | | 177 | | } |
| | | 178 | | } |
| | | 179 | | } |
| | | 180 | | |
| | | 181 | | private async Task WaitForSignalOrDelayAsync(CancellationToken cancellationToken) |
| | | 182 | | { |
| | | 183 | | // The WhenAny loser is cancelled via the per-iteration linked source (mirroring the |
| | | 184 | | // channel-side CollectDispatchScopeAsync): an abandoned WaitToReadAsync would otherwise |
| | | 185 | | // stay parked in the channel's blocked-reader list until the next signal — one per empty |
| | | 186 | | // poll, accumulating without bound on an idle queue. |
| | | 187 | | using var iteration = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken); |
| | | 188 | | var delay = Task.Delay(SubscriberOptions.EmptyPollDelay, iteration.Token); |
| | | 189 | | var signal = _signals.Reader.WaitToReadAsync(iteration.Token).AsTask(); |
| | | 190 | | var completed = await Task.WhenAny(delay, signal).ConfigureAwait(false); |
| | | 191 | | iteration.Cancel(); |
| | | 192 | | if (completed == signal) |
| | | 193 | | { |
| | | 194 | | await signal.ConfigureAwait(false); |
| | | 195 | | while (_signals.Reader.TryRead(out _)) |
| | | 196 | | { |
| | | 197 | | } |
| | | 198 | | } |
| | | 199 | | } |
| | | 200 | | } |
| | | 201 | | |
| | | 202 | | /// <summary>Consumes worker-job documents and executes them through the AsyncResponse ingress.</summary> |
| | | 203 | | internal sealed class MongoDbWorkerSubscriber : MongoDbSubscriberService |
| | | 204 | | { |
| | | 205 | | private readonly IAsyncResponseIngress _ingress; |
| | | 206 | | |
| | | 207 | | public MongoDbWorkerSubscriber( |
| | | 208 | | IOptions<MongoDbAsyncResponseTransportOptions> options, |
| | | 209 | | MongoDbTransportStore store, |
| | | 210 | | IAsyncResponseIngress ingress, |
| | | 211 | | ILogger<MongoDbWorkerSubscriber> logger) |
| | | 212 | | : base(options, store, logger) |
| | | 213 | | => _ingress = ingress; |
| | | 214 | | |
| | | 215 | | protected override string Queue => Options.WorkerQueue; |
| | | 216 | | protected override MongoDbSubscriberOptions SubscriberOptions => Options.WorkerSubscriber; |
| | | 217 | | protected override MongoDbSubscriberRole Role => MongoDbSubscriberRole.Worker; |
| | | 218 | | |
| | | 219 | | protected override Task HandleMessageAsync(MongoDbTransportDelivery delivery, CancellationToken cancellationToken) |
| | | 220 | | => _ingress.HandleWorkerMessageAsync(delivery.Payload); |
| | | 221 | | } |
| | | 222 | | |
| | | 223 | | /// <summary>Consumes response documents and feeds them into the AsyncResponse ingress.</summary> |
| | | 224 | | internal sealed class MongoDbResponseIngressSubscriber : MongoDbSubscriberService |
| | | 225 | | { |
| | | 226 | | private readonly IAsyncResponseIngress _ingress; |
| | | 227 | | |
| | | 228 | | public MongoDbResponseIngressSubscriber( |
| | | 229 | | IOptions<MongoDbAsyncResponseTransportOptions> options, |
| | | 230 | | MongoDbTransportStore store, |
| | | 231 | | IAsyncResponseIngress ingress, |
| | | 232 | | ILogger<MongoDbResponseIngressSubscriber> logger) |
| | 200 | 233 | | : base(options, store, logger) |
| | 200 | 234 | | => _ingress = ingress; |
| | | 235 | | |
| | 885 | 236 | | protected override string Queue => Options.ResponseQueue; |
| | 1574 | 237 | | protected override MongoDbSubscriberOptions SubscriberOptions => Options.ResponseSubscriber; |
| | 584 | 238 | | protected override MongoDbSubscriberRole Role => MongoDbSubscriberRole.ResponseIngress; |
| | | 239 | | |
| | | 240 | | protected override Task HandleMessageAsync(MongoDbTransportDelivery delivery, CancellationToken cancellationToken) |
| | | 241 | | { |
| | 4 | 242 | | var correlationId = !_ingress.IsOverInboundBudget(delivery.Payload) |
| | 4 | 243 | | ? MongoDbCorrelationIdExtractor.Extract(delivery.Headers, delivery.Payload, Options) |
| | 4 | 244 | | : null; |
| | 4 | 245 | | return _ingress.HandleResponseMessageAsync(delivery.Payload, correlationId); |
| | | 246 | | } |
| | | 247 | | } |