/// <summary>
/// Receives a batch of <see cref="EventData" /> from the Event Hub partition.
/// </summary>
///
/// <param name="maximumMessageCount">The maximum number of messages to receive in this batch.</param>
/// <param name="maximumWaitTime">The maximum amount of time to wait to build up the requested message count for the batch; if not specified, the default wait time specified when the consumer was created will be used.</param>
/// <param name="cancellationToken">An optional <see cref="CancellationToken"/> instance to signal the request to cancel the operation.</param>
///
/// <returns>The batch of <see cref="EventData" /> from the Event Hub partition this consumer is associated with. If no events are present, an empty enumerable is returned.</returns>
///
public override async Task <IEnumerable <EventData> > ReceiveAsync(int maximumMessageCount,
TimeSpan?maximumWaitTime,
CancellationToken cancellationToken)
{
Argument.AssertNotClosed(_closed, nameof(AmqpEventHubConsumer));
Argument.AssertAtLeast(maximumMessageCount, 1, nameof(maximumMessageCount));
var receivedEventCount = 0;
var failedAttemptCount = 0;
var waitTime = (maximumWaitTime ?? _tryTimeout);
var link = default(ReceivingAmqpLink);
var retryDelay = default(TimeSpan?);
var amqpMessages = default(IEnumerable <AmqpMessage>);
var receivedEvents = default(List <EventData>);
var stopWatch = Stopwatch.StartNew();
try
{
while (!cancellationToken.IsCancellationRequested)
{
try
{
EventHubsEventSource.Log.EventReceiveStart(EventHubName, ConsumerGroup, PartitionId);
link = await ReceiveLink.GetOrCreateAsync(UseMinimum(ConnectionScope.SessionTimeout, _tryTimeout)).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested <TaskCanceledException>();
var messagesReceived = await Task.Factory.FromAsync
(
(callback, state) => link.BeginReceiveMessages(maximumMessageCount, waitTime, callback, state),
(asyncResult) => link.EndReceiveMessages(asyncResult, out amqpMessages),
TaskCreationOptions.RunContinuationsAsynchronously
).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested <TaskCanceledException>();
// If event messages were received, then package them for consumption and
// return them.
if ((messagesReceived) && (amqpMessages != null))
{
receivedEvents ??= new List <EventData>();
foreach (AmqpMessage message in amqpMessages)
{
link.DisposeDelivery(message, true, AmqpConstants.AcceptedOutcome);
receivedEvents.Add(MessageConverter.CreateEventFromMessage(message));
message.Dispose();
}
receivedEventCount = receivedEvents.Count;
if ((Options.TrackLastEnqueuedEventInformation) && (receivedEventCount > 0))
{
LastReceivedEvent = receivedEvents[receivedEventCount - 1];
}
return(receivedEvents);
}
// No events were available.
return(Enumerable.Empty <EventData>());
}
catch (EventHubsTimeoutException)
{
// Because the timeout specified with the request is intended to be the maximum
// amount of time to wait for events, a timeout isn't considered an error condition,
// rather a sign that no events were available in the requested period.
return(Enumerable.Empty <EventData>());
}
catch (AmqpException amqpException)
{
throw AmqpError.CreateExceptionForError(amqpException.Error, EventHubName);
}
catch (Exception ex)
{
// Determine if there should be a retry for the next attempt; if so enforce the delay but do not quit the loop.
// Otherwise, bubble the exception.
++failedAttemptCount;
retryDelay = _retryPolicy.CalculateRetryDelay(ex, failedAttemptCount);
if ((retryDelay.HasValue) && (!ConnectionScope.IsDisposed) && (!cancellationToken.IsCancellationRequested))
{
EventHubsEventSource.Log.EventReceiveError(EventHubName, ConsumerGroup, PartitionId, ex.Message);
await Task.Delay(UseMinimum(retryDelay.Value, waitTime.CalculateRemaining(stopWatch.Elapsed)), cancellationToken).ConfigureAwait(false);
}
else
{
throw;
}
}
}
// If no value has been returned nor exception thrown by this point,
// then cancellation has been requested.
throw new TaskCanceledException();
}
catch (Exception ex)
{
EventHubsEventSource.Log.EventReceiveError(EventHubName, ConsumerGroup, PartitionId, ex.Message);
throw;
}
finally
{
stopWatch.Stop();
EventHubsEventSource.Log.EventReceiveComplete(EventHubName, ConsumerGroup, PartitionId, receivedEventCount);
}
}
/// <summary>
/// Receives a batch of <see cref="EventData" /> from the Event Hub partition.
/// </summary>
///
/// <param name="maximumMessageCount">The maximum number of messages to receive in this batch.</param>
/// <param name="maximumWaitTime">The maximum amount of time to wait to build up the requested message count for the batch; if not specified, the per-try timeout specified by the retry policy will be used.</param>
/// <param name="cancellationToken">An optional <see cref="CancellationToken"/> instance to signal the request to cancel the operation.</param>
///
/// <returns>The batch of <see cref="EventData" /> from the Event Hub partition this consumer is associated with. If no events are present, an empty set is returned.</returns>
///
public override async Task <IReadOnlyList <EventData> > ReceiveAsync(int maximumMessageCount,
TimeSpan?maximumWaitTime,
CancellationToken cancellationToken)
{
Argument.AssertNotClosed(_closed, nameof(AmqpConsumer));
Argument.AssertAtLeast(maximumMessageCount, 1, nameof(maximumMessageCount));
var receivedEventCount = 0;
var failedAttemptCount = 0;
var tryTimeout = RetryPolicy.CalculateTryTimeout(0);
var waitTime = (maximumWaitTime ?? tryTimeout);
var link = default(ReceivingAmqpLink);
var retryDelay = default(TimeSpan?);
var amqpMessages = default(IEnumerable <AmqpMessage>);
var receivedEvents = default(List <EventData>);
var lastReceivedEvent = default(EventData);
var stopWatch = ValueStopwatch.StartNew();
try
{
while ((!cancellationToken.IsCancellationRequested) && (!_closed))
{
try
{
// Creation of the link happens without explicit knowledge of the cancellation token
// used for this operation; validate the token state before attempting link creation and
// again after the operation completes to provide best efforts in respecting it.
EventHubsEventSource.Log.EventReceiveStart(EventHubName, ConsumerGroup, PartitionId);
cancellationToken.ThrowIfCancellationRequested <TaskCanceledException>();
link = await ReceiveLink.GetOrCreateAsync(UseMinimum(ConnectionScope.SessionTimeout, tryTimeout)).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested <TaskCanceledException>();
var messagesReceived = await Task.Factory.FromAsync
(
(callback, state) => link.BeginReceiveMessages(maximumMessageCount, waitTime, callback, state),
(asyncResult) => link.EndReceiveMessages(asyncResult, out amqpMessages),
TaskCreationOptions.RunContinuationsAsynchronously
).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested <TaskCanceledException>();
// If event messages were received, then package them for consumption and
// return them.
if ((messagesReceived) && (amqpMessages != null))
{
receivedEvents ??= new List <EventData>();
foreach (AmqpMessage message in amqpMessages)
{
link.DisposeDelivery(message, true, AmqpConstants.AcceptedOutcome);
receivedEvents.Add(MessageConverter.CreateEventFromMessage(message));
message.Dispose();
}
receivedEventCount = receivedEvents.Count;
if (receivedEventCount > 0)
{
lastReceivedEvent = receivedEvents[receivedEventCount - 1];
if (lastReceivedEvent.Offset > long.MinValue)
{
CurrentEventPosition = EventPosition.FromOffset(lastReceivedEvent.Offset, false);
}
if (TrackLastEnqueuedEventProperties)
{
LastReceivedEvent = lastReceivedEvent;
}
}
return(receivedEvents);
}
// No events were available.
return(EmptyEventSet);
}
catch (EventHubsException ex) when(ex.Reason == EventHubsException.FailureReason.ServiceTimeout)
{
// Because the timeout specified with the request is intended to be the maximum
// amount of time to wait for events, a timeout isn't considered an error condition,
// rather a sign that no events were available in the requested period.
return(EmptyEventSet);
}
catch (Exception ex)
{
Exception activeEx = ex.TranslateServiceException(EventHubName);
// Determine if there should be a retry for the next attempt; if so enforce the delay but do not quit the loop.
// Otherwise, bubble the exception.
++failedAttemptCount;
retryDelay = RetryPolicy.CalculateRetryDelay(activeEx, failedAttemptCount);
if ((retryDelay.HasValue) && (!ConnectionScope.IsDisposed) && (!cancellationToken.IsCancellationRequested))
{
EventHubsEventSource.Log.EventReceiveError(EventHubName, ConsumerGroup, PartitionId, activeEx.Message);
await Task.Delay(UseMinimum(retryDelay.Value, waitTime.CalculateRemaining(stopWatch.GetElapsedTime())), cancellationToken).ConfigureAwait(false);
tryTimeout = RetryPolicy.CalculateTryTimeout(failedAttemptCount);
}
else if (ex is AmqpException)
{
ExceptionDispatchInfo.Capture(activeEx).Throw();
}
else
{
throw;
}
}
}
// If no value has been returned nor exception thrown by this point,
// then cancellation has been requested.
throw new TaskCanceledException();
}
catch (TaskCanceledException)
{
throw;
}
catch (Exception ex)
{
EventHubsEventSource.Log.EventReceiveError(EventHubName, ConsumerGroup, PartitionId, ex.Message);
throw;
}
finally
{
EventHubsEventSource.Log.EventReceiveComplete(EventHubName, ConsumerGroup, PartitionId, receivedEventCount);
}
}
/// <summary>
/// Receives a batch of <see cref="EventData" /> from the Event Hub partition.
/// </summary>
///
/// <param name="maximumEventCount">The maximum number of messages to receive in this batch.</param>
/// <param name="maximumWaitTime">The maximum amount of time to wait for events to become available, if no events can be read from the prefetch queue. If not specified, the per-try timeout specified by the retry policy will be used.</param>
/// <param name="cancellationToken">An optional <see cref="CancellationToken"/> instance to signal the request to cancel the operation.</param>
///
/// <returns>The batch of <see cref="EventData" /> from the Event Hub partition this consumer is associated with. If no events are present, an empty set is returned.</returns>
///
/// <remarks>
/// When events are available in the prefetch queue, they will be used to form the batch as quickly as possible without waiting for additional events from the
/// Event Hubs service to try and meet the requested <paramref name="maximumEventCount" />. When no events are available in prefetch, the receiver will wait up
/// to the <paramref name="maximumWaitTime"/> for events to be read from the service. Once any events are available, they will be used to form the batch immediately.
/// </remarks>
///
public override async Task <IReadOnlyList <EventData> > ReceiveAsync(int maximumEventCount,
TimeSpan?maximumWaitTime,
CancellationToken cancellationToken)
{
Argument.AssertNotClosed(_closed, nameof(AmqpConsumer));
Argument.AssertNotClosed(ConnectionScope.IsDisposed, nameof(EventHubConnection));
Argument.AssertAtLeast(maximumEventCount, 1, nameof(maximumEventCount));
var receivedEventCount = 0;
var failedAttemptCount = 0;
var tryTimeout = RetryPolicy.CalculateTryTimeout(0);
var waitTime = (maximumWaitTime ?? tryTimeout);
var operationId = Guid.NewGuid().ToString("D", CultureInfo.InvariantCulture);
var link = default(ReceivingAmqpLink);
var retryDelay = default(TimeSpan?);
var receivedEvents = default(List <EventData>);
var lastReceivedEvent = default(EventData);
var stopWatch = ValueStopwatch.StartNew();
try
{
while ((!cancellationToken.IsCancellationRequested) && (!_closed))
{
try
{
// Creation of the link happens without explicit knowledge of the cancellation token
// used for this operation; validate the token state before attempting link creation and
// again after the operation completes to provide best efforts in respecting it.
EventHubsEventSource.Log.EventReceiveStart(EventHubName, ConsumerGroup, PartitionId, operationId);
link = await ReceiveLink.GetOrCreateAsync(UseMinimum(ConnectionScope.SessionTimeout, tryTimeout), cancellationToken).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested <TaskCanceledException>();
var messagesReceived = await link.ReceiveMessagesAsync(maximumEventCount, ReceiveBuildBatchInterval, waitTime, cancellationToken).ConfigureAwait(false);
// If no messages were received, then just return the empty set.
if (messagesReceived == null)
{
return(EmptyEventSet);
}
// If event messages were received, then package them for consumption and
// return them.
foreach (AmqpMessage message in messagesReceived)
{
receivedEvents ??= new List <EventData>();
link.DisposeDelivery(message, true, AmqpConstants.AcceptedOutcome);
receivedEvents.Add(MessageConverter.CreateEventFromMessage(message));
message.Dispose();
receivedEventCount = receivedEvents.Count;
}
if (receivedEventCount > 0)
{
lastReceivedEvent = receivedEvents[receivedEventCount - 1];
if (lastReceivedEvent.Offset > long.MinValue)
{
CurrentEventPosition = EventPosition.FromOffset(lastReceivedEvent.Offset, false);
}
if (TrackLastEnqueuedEventProperties)
{
LastReceivedEvent = lastReceivedEvent;
}
}
return(receivedEvents ?? EmptyEventSet);
}
catch (EventHubsException ex) when(ex.Reason == EventHubsException.FailureReason.ServiceTimeout)
{
// Because the timeout specified with the request is intended to be the maximum
// amount of time to wait for events, a timeout isn't considered an error condition,
// rather a sign that no events were available in the requested period.
return(EmptyEventSet);
}
catch (Exception ex)
{
Exception activeEx = ex.TranslateServiceException(EventHubName);
// If the partition was stolen determine the correct action to take for
// capturing it with respect to whether the consumer should be invalidated.
//
// In either case, it is a terminal exception and will not trigger a retry;
// allow the normal error handling flow to surface the exception.
if (ex.IsConsumerPartitionStolenException())
{
// If the consumer should be invalidated, capture the exception
// and force-close the link. This will ensure that the next operation
// will surface it.
if (InvalidateConsumerWhenPartitionStolen)
{
_activePartitionStolenException = ex;
CloseConsumerLink(link);
}
else
{
// If the consumer should not be invalidated, clear any previously captured exception to avoid
// surfacing the failure multiple times. If the link is stolen after this operation, it will
// be intercepted and handled as needed.
_activePartitionStolenException = null;
}
}
// Determine if there should be a retry for the next attempt; if so enforce the delay but do not quit the loop.
// Otherwise, bubble the exception.
++failedAttemptCount;
retryDelay = RetryPolicy.CalculateRetryDelay(activeEx, failedAttemptCount);
if ((retryDelay.HasValue) && (!ConnectionScope.IsDisposed) && (!_closed) && (!cancellationToken.IsCancellationRequested))
{
EventHubsEventSource.Log.EventReceiveError(EventHubName, ConsumerGroup, PartitionId, operationId, activeEx.Message);
await Task.Delay(UseMinimum(retryDelay.Value, waitTime.CalculateRemaining(stopWatch.GetElapsedTime())), cancellationToken).ConfigureAwait(false);
tryTimeout = RetryPolicy.CalculateTryTimeout(failedAttemptCount);
}
else if (ex is AmqpException)
{
ExceptionDispatchInfo.Capture(activeEx).Throw();
}
else
{
throw;
}
}
}
// If no value has been returned nor exception thrown by this point,
// then cancellation has been requested.
throw new TaskCanceledException();
}
catch (TaskCanceledException)
{
throw;
}
catch (Exception ex)
{
EventHubsEventSource.Log.EventReceiveError(EventHubName, ConsumerGroup, PartitionId, operationId, ex.Message);
throw;
}
finally
{
EventHubsEventSource.Log.EventReceiveComplete(EventHubName, ConsumerGroup, PartitionId, operationId, failedAttemptCount, receivedEventCount);
}
}
