public async Task <StreamReadResults> ReadFrom(string streamId, Func <IAmAStoredEvent, bool> predicate = null, Direction direction = Direction.Backwards, CancellationToken cancellationToken = default)
{
var readResult = client.ReadStreamAsync(direction,
streamId,
direction == Direction.Backwards ? StreamPosition.End : StreamPosition.Start,
resolveLinkTos: true,
configureOperationOptions: options => options.TimeoutAfter = TimeSpan.FromSeconds(30),
cancellationToken: cancellationToken);
bool streamExists = false;
try
{
var readState = await readResult.ReadState;
streamExists = readState == ReadState.Ok;
}
#pragma warning disable 168
catch (StreamDeletedException ex)
// This happens when the stream is hard-deleted. We don't want to throw in that case
#pragma warning restore 168
{
streamExists = false;
}
if (!streamExists)
{
return(new StreamReadResults(emptyReadResult, false, StreamPosition.FromInt64(-1)));
}
predicate ??= _ => true;
var lastIndex = (await client.ReadStreamAsync(Direction.Backwards, streamId,
revision: StreamPosition.End,
maxCount: 1,
resolveLinkTos: false).FirstAsync(cancellationToken)).OriginalEventNumber;
IAsyncEnumerable <StoredEvent> storedEvents;
if (direction == Direction.Backwards)
{
storedEvents = readResult
// Trust me, resharper is wrong in this one. Event can be null
// ReSharper disable once ConditionIsAlwaysTrueOrFalse
.Where(e => e.Event != null)
.Select((e, _) => e.Event.ToStoredEvent(stateFactory))
.TakeWhile(e => e.DeserializedEvent is not EntitySoftDeleted)
.Where(e => predicate(e));
}
else
{
storedEvents = readResult
// Trust me, resharper is wrong in this one. Event can be null
// ReSharper disable once ConditionIsAlwaysTrueOrFalse
.Where(e => e.Event != null)
.Select((e, c) => e.Event.ToStoredEvent(stateFactory))
.Where(e => predicate(e));
}
return(new StreamReadResults(storedEvents, true, lastIndex));
}
private static async Task SubscribeToStream(EventStoreClient client)
{
#region subscribe-to-stream
await client.SubscribeToStreamAsync("some-stream",
async (subscription, evnt, cancellationToken) => {
Console.WriteLine($"Received event {evnt.OriginalEventNumber}@{evnt.OriginalStreamId}");
await HandleEvent(evnt);
});
#endregion subscribe-to-stream
#region subscribe-to-stream-from-position
await client.SubscribeToStreamAsync(
"some-stream",
StreamPosition.FromInt64(20),
EventAppeared);
#endregion subscribe-to-stream-from-position
#region subscribe-to-stream-live
await client.SubscribeToStreamAsync(
"some-stream",
StreamPosition.End,
EventAppeared);
#endregion subscribe-to-stream-live
#region subscribe-to-stream-resolving-linktos
await client.SubscribeToStreamAsync(
"$et-myEventType",
StreamPosition.Start,
EventAppeared,
resolveLinkTos : true);
#endregion subscribe-to-stream-resolving-linktos
#region subscribe-to-stream-subscription-dropped
var checkpoint = StreamPosition.Start;
await client.SubscribeToStreamAsync(
"some-stream",
checkpoint,
eventAppeared : async(subscription, evnt, cancellationToken) => {
await HandleEvent(evnt);
checkpoint = evnt.OriginalEventNumber;
},
subscriptionDropped : ((subscription, reason, exception) => {
Console.WriteLine($"Subscription was dropped due to {reason}. {exception}");
if (reason != SubscriptionDroppedReason.Disposed)
{
// Resubscribe if the client didn't stop the subscription
Resubscribe(checkpoint);
}
}));
#endregion subscribe-to-stream-subscription-dropped
}
/// <summary>
/// Reads the events.
/// </summary>
/// <param name="streamName">Name of the stream.</param>
/// <param name="fromVersion">From version.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns></returns>
public async Task <List <ResolvedEvent> > ReadEvents(String streamName,
Int64 fromVersion,
CancellationToken cancellationToken)
{
this.LogInformation($"About to read events from Stream {streamName} fromVersion is {fromVersion}");
List <ResolvedEvent> resolvedEvents = new List <ResolvedEvent>();
EventStoreClient.ReadStreamResult response;
List <ResolvedEvent> events;
do
{
response = this.EventStoreClient.ReadStreamAsync(Direction.Forwards,
streamName,
StreamPosition.FromInt64(fromVersion),
2,
resolveLinkTos: true,
cancellationToken: cancellationToken);
// Check the read state
ReadState readState = await response.ReadState;
if (readState == ReadState.StreamNotFound)
{
this.LogInformation($"Read State from Stream {streamName} is {readState}");
return(null);
}
events = await response.ToListAsync(cancellationToken);
resolvedEvents.AddRange(events);
fromVersion += events.Count;
} while (events.Any());
this.LogInformation($"About to return {resolvedEvents.Count} events from Stream {streamName}");
return(resolvedEvents);
}
/// <summary>
/// Event Store Initialize (read events and subscribe at the end)
/// </summary>
private async Task <bool> Initialize(string stream)
{
var _init = _position;
try
{
var ec_stream = _client.ReadStreamAsync(
Direction.Forwards, stream,
StreamPosition.FromInt64(_position),
maxCount: 100
);
if (await ec_stream.ReadState == ReadState.StreamNotFound)
{
await _client.SubscribeToStreamAsync(stream, SubscribeReturn);
return(false);
}
foreach (var vnt in ec_stream.ToEnumerable().AsParallel())
{
await SubscribeReturn(null, vnt, CancellationToken.None);
}
await ec_stream.DisposeAsync();
}
catch { }
if (_init == _position)
{
await _client.SubscribeToStreamAsync(stream, StreamPosition.FromInt64(_position), SubscribeReturn);
return(false);
}
return(true);
}
protected override async Task <EventSubscription> Subscribe(
Checkpoint checkpoint,
CancellationToken cancellationToken
)
{
var subTask = checkpoint.Position == null
? EventStoreClient.SubscribeToStreamAsync(
_options.StreamName,
HandleEvent,
_options.ResolveLinkTos,
HandleDrop,
_options.ConfigureOperation,
_options.Credentials,
cancellationToken
)
: EventStoreClient.SubscribeToStreamAsync(
_options.StreamName,
StreamPosition.FromInt64((long)checkpoint.Position),
HandleEvent,
_options.ResolveLinkTos,
HandleDrop,
_options.ConfigureOperation,
_options.Credentials,
cancellationToken
);
var sub = await subTask.Ignore();
return(new EventSubscription(SubscriptionId, new Stoppable(() => sub.Dispose())));
async Task HandleEvent(EventStore.Client.StreamSubscription _, ResolvedEvent re, CancellationToken ct)
{
await Handler(AsReceivedEvent(re), ct).Ignore();
}
void HandleDrop(EventStore.Client.StreamSubscription _, SubscriptionDroppedReason reason, Exception?ex)
=> Dropped(EsdbMappings.AsDropReason(reason), ex);
ReceivedEvent AsReceivedEvent(ResolvedEvent re)
{
var evt = DeserializeData(
re.Event.ContentType,
re.Event.EventType,
re.Event.Data,
re.Event.EventStreamId,
re.Event.EventNumber
);
return(new ReceivedEvent(
re.Event.EventId.ToString(),
re.Event.EventType,
re.Event.ContentType,
re.Event.Position.CommitPosition,
re.Event.EventNumber,
re.Event.EventStreamId,
re.Event.EventNumber,
re.Event.Created,
evt
// re.Event.Metadata
));
}
}
public static StreamPosition AsStreamPosition(this StreamReadPosition position) => StreamPosition.FromInt64(position.Value);
public static StreamPosition AsStreamPosition(this StreamTruncatePosition position) => StreamPosition.FromInt64(position.Value);
public override async IAsyncEnumerable <IDomainEventDescriptor> GetAggregateEvents <TKey>(string aggregateType, TKey id, long afterVersion, [EnumeratorCancellation] CancellationToken cancellationToken)
{
var streamName = GenerateStreamId(aggregateType, id);
ReadStreamResult eventStoreDbEvents;
if (afterVersion == -1)
{
eventStoreDbEvents = EventStoreClient.ReadStreamAsync(
Direction.Forwards,
streamName,
StreamPosition.Start,
cancellationToken: cancellationToken);
}
else
{
eventStoreDbEvents = EventStoreClient.ReadStreamAsync(
Direction.Forwards,
streamName,
StreamPosition.FromInt64(afterVersion + 1),
cancellationToken: cancellationToken);
}
if (await eventStoreDbEvents.ReadState == ReadState.StreamNotFound)
{
yield break;
}
var eventDescriptors = eventStoreDbEvents.Select(@event =>
{
var version = @event.Event.EventNumber.ToInt64();
var bsonData = @event.Event.Data;
var bsonMetadata = @event.Event.Metadata;
var eventType = @event.Event.EventType;
DomainEventDescriptor descriptor;
using (var stream = bsonData.AsStream())
using (var reader = new BsonDataReader(stream))
{
JsonSerializer serializer = new JsonSerializer();
serializer.TypeNameHandling = TypeNameHandling.All;
var domainEvent = serializer.Deserialize <IDomainEvent>(reader);
descriptor = DomainEventDescriptor.FromStore(aggregateType, id.ToString(), domainEvent, version, eventType);
}
using (var stream = bsonMetadata.AsStream())
using (var reader = new BsonDataReader(stream))
{
JsonSerializer serializer = new JsonSerializer();
serializer.TypeNameHandling = TypeNameHandling.All;
var metadata = serializer.Deserialize <IDictionary <string, string> >(reader);
foreach (var keyValue in metadata)
{
descriptor.Metadata.Add(keyValue.Key, keyValue.Value);
}
}
return(descriptor);
});
await foreach (var eventDescriptor in eventDescriptors)
{
yield return(eventDescriptor);
}
}
public async Task <IEnumerable <DomainEvent> > GetEvents <T>(Guid id, Int32 eventsPerRequest = 100) where T : AggregateRootWithEvents
{
String streamName = GetStreamId <T>(id);
var encoding = new UTF8Encoding();
var firstEvent = _client.ReadStreamAsync(Direction.Forwards, streamName, StreamPosition.Start, 1);
var state = await firstEvent.ReadState;
if (state == ReadState.StreamNotFound)
{
return(Array.Empty <DomainEvent>());
}
List <DomainEvent> domainEvents = new();
Int32 streamPosition = 0;
while (true)
{
var partialEvents = _client.ReadStreamAsync(Direction.Forwards, streamName, StreamPosition.FromInt64(streamPosition), eventsPerRequest);
var items = await partialEvents.ToListAsync();
if (items.Count == 0)
{
break;
}
foreach (var item in items)
{
EventMeta meta = System.Text.Json.JsonSerializer.Deserialize <EventMeta>(new ReadOnlySpan <Byte>(item.Event.Metadata.ToArray()));
String content = encoding.GetString(item.Event.Data.ToArray());
var domainEvent = (DomainEvent)JsonConvert.DeserializeObject(content, Type.GetType(meta.BodyType), _jsonSerializerSettings);
domainEvents.Add(domainEvent);
}
streamPosition += eventsPerRequest;
}
return(domainEvents);
}