/// <summary>
/// Fetches raw events along with their deserialized EventDocument-derived instances when possible, returning an enumerable of
/// (raw, doc, error) tuples
/// </summary>
/// <param name="consumer">Event consumer implementation</param>
/// <param name="route">Queue designator</param>
/// <param name="partition">Logical partition to fetch from <see cref="IEventConsumer.PartitionCount"/></param>
/// <param name="checkpoint">A point in time as of which to fetch</param>
/// <param name="skip">Number of events to skip in the beginning</param>
/// <param name="count">Number of events to fetch</param>
/// <param name="lossMode">Data loss tolerance</param>
/// <returns>
/// A tuple of `raw` event representation, its converted EventDocument-derived instance `doc`, and an error (if any) which surfaced
/// during event doc deserialization attempt, thus `doc` and `err` are mutually exclusive
/// </returns>
public static async Task <IEnumerable <(Event raw, EventDocument doc, Exception err)> > FetchEventDocsAsync(this IEventConsumer consumer,
Route route,
int partition,
ulong checkpoint,
int skip,
int count,
DataLossMode lossMode = DataLossMode.Default)
{
var got = await consumer.NonNull(nameof(consumer))
.FetchAsync(route, partition, checkpoint, skip, count, lossMode);
using (var ms = new IO.BufferSegmentReadingStream())
{
return(got.Select(e => {
EventDocument doc = null;
Exception error = null;
try
{
if (e.ContentType == CONTENT_TYPE_JSON_DOC && e.Content != null)
{
ms.UnsafeBindBuffer(e.Content, 0, e.Content.Length);
var map = JsonReader.DeserializeDataObject(ms, EVENT_JSON_ENCODING, true) as JsonDataMap;
doc = JsonReader.ToDoc <EventDocument>(map, fromUI: false);
}
}
catch (Exception err)
{
error = err;
}
return (raw: e, doc: doc, err: error);
}).ToArray());
}
}
/// <summary>
/// Post event document using processing Route obtained from EventDocument instance and
/// serializing document using json. The content type header is not set by this method.
/// Note: When returned WriteResult does not satisfy caller requirements, this method does NOT
/// give caller a chance to re-post the SAME raw <see cref="Event"/> instance as the onus
/// of failure handling is on the caller.
/// You can use <see cref="GetRawEventForDocument(IEventProducer, EventDocument, JsonDataMap)"/>
/// if you want to re-post the SAME event instance
/// </summary>
/// <param name="producer">Producer to post event into</param>
/// <param name="evtDoc">EventDocument-derivative instance</param>
/// <param name="headers">Event headers or null</param>
/// <param name="lossMode">Data loss mode, if null then default used from doc declaration</param>
/// <returns>WriteResult - how many nodes tried/succeeded/failed</returns>
public static async Task <WriteResult> PostEventDocumentAsync(this IEventProducer producer,
EventDocument evtDoc,
JsonDataMap headers = null,
DataLossMode?lossMode = null)
{
var(attr, partition, rawEvent) = GetRawEventForDocument(producer, evtDoc, headers);
var result = await producer.PostAsync(attr.Route, partition, rawEvent, lossMode ?? attr.LossMode).ConfigureAwait(false);
return(result);
}
/// <summary>
/// Creates a <see cref="Event"/> instance out of <see cref="EventDocument"/> instance
/// which can then be posted into IEventProducer. You can use this method to obtain raw event
/// once in order to possibly re-try posting if post fails. The system maintains idempotency of
/// Event posts, therefore a caller may hang to returned Event instance to retry failed posting
/// </summary>
/// <param name="producer">Producer to eventually post event into</param>
/// <param name="evtDoc">EventDocument-derivative instance</param>
/// <param name="headers">Event headers or null</param>
/// <returns>
/// A tuple of (EventAttribute attr, ShardKey partition, Event evt) suitable for
/// making a call to<see cref="IEventProducer.PostAsync(Route, ShardKey, Event, DataLossMode)"/>
/// </returns>
public static (EventAttribute attr, ShardKey partition, Event evt) GetRawEventForDocument(this IEventProducer producer,
EventDocument evtDoc,
JsonDataMap headers = null)
{
var partition = evtDoc.NonNull(nameof(evtDoc)).GetEventPartition();
var eventHeaders = evtDoc.GetEventHeaders(headers);
var rawHeaders = eventHeaders != null?JsonWriter.Write(eventHeaders, JsonWritingOptions.CompactRowsAsMap) : null;
var rawJson = JsonWriter.WriteToBuffer(evtDoc, JsonWritingOptions.CompactRowsAsMap, EVENT_JSON_ENCODING);
var rawEvent = producer.NonNull(nameof(producer))
.MakeNew(CONTENT_TYPE_JSON_DOC, rawJson, rawHeaders);
var attr = EventAttribute.GetFor(evtDoc.GetType());
return(attr, partition, rawEvent);
}
