private async Task ProcessEventsAsync(OperationContext context, List <EventData> messages)
{
// Tracking raw messages count.
Counters[ReceivedEventHubEventsCount].Add(messages.Count);
CacheActivityTracker.AddValue(CaSaaSActivityTrackingCounters.ReceivedEventHubMessages, messages.Count);
// Creating nested context for all the processing operations.
context = context.CreateNested(nameof(EventHubContentLocationEventStore));
if (messages.Count == 0)
{
// This probably does not actually occur, but just in case, ignore empty message batch.
// NOTE: We do this after logging to ensure we notice if the we are getting empty message batches.
return;
}
var state = new SharedEventProcessingState(context, this, messages);
if (_eventProcessingBlocks != null)
{
await context
.CreateOperation(Tracer, () => sendToActionBlockAsync(state))
.WithOptions(traceOperationStarted: false, endMessageFactory: r => $"TotalQueueSize={Interlocked.Read(ref _queueSize)}")
.RunAsync(caller: "SendToActionBlockAsync")
.TraceIfFailure(context);
}
else
{
await ProcessEventsCoreAsync(new ProcessEventsInput(state, messages, actionBlockIndex : -1, store : this), EventDataSerializer);
}
async Task <BoolResult> sendToActionBlockAsync(SharedEventProcessingState st)
{
// This local function "sends" a message into an action block based on the sender's hash code to process events in parallel from different machines.
// (keep in mind, that the data from the same machine should be processed sequentially, because events order matters).
// Then, it creates a local counter for each processing operation to track the results for the entire batch.
foreach (var messageGroup in messages.GroupBy(GetProcessingIndex))
{
int actionBlockIndex = messageGroup.Key;
var eventProcessingBlock = _eventProcessingBlocks ![actionBlockIndex];
var input = new ProcessEventsInput(st, messageGroup, actionBlockIndex, this);
var sendAsyncTask = eventProcessingBlock.SendAsync(input);
if (sendAsyncTask.Status == TaskStatus.WaitingForActivation)
{
// The action block is busy. It means that its most likely full.
Tracer.Debug(context, $"Action block {actionBlockIndex} is busy. Block's queue size={eventProcessingBlock.InputCount}.");
}
bool success = await sendAsyncTask;
if (!success)
{
// NOTE: This case should not actually occur.
// Complete the operation in case we couldn't send to the action block to prevent pending event queue from getting backlogged.
input.Complete();
return(new BoolResult("Failed to add message to an action block."));
}
}
private async Task ProcessEventsAsync(OperationContext context, List <EventData> messages)
{
// Creating nested context for all the processing operations.
context = context.CreateNested();
string asyncProcessing = _eventProcessingBlocks != null ? "on" : "off";
Tracer.Info(context, $"{Tracer.Name}: Received {messages.Count} events from Event Hub. Async processing is '{asyncProcessing}'.");
if (messages.Count == 0)
{
// This probably does not actually occur, but just in case, ignore empty message batch.
// NOTE: We do this after logging to ensure we notice if the we are getting empty message batches.
return;
}
var state = new SharedEventProcessingState(context, this, messages);
if (_eventProcessingBlocks != null)
{
// Creating nested context to correlate all the processing operations.
context = context.CreateNested();
await context.PerformOperationAsync(
Tracer,
() => sendToActionBlockAsync(),
traceOperationStarted : false).TraceIfFailure(context);
}
else
{
await ProcessEventsCoreAsync(new ProcessEventsInput(state, messages), EventDataSerializer, index : 0);
}
async Task <SendToActionBlockResult> sendToActionBlockAsync()
{
// This local function "sends" a message into an action block based on the sender's hash code to process events in parallel from different machines.
// (keep in mind, that the data from the same machine should be processed sequentially, because events order matters).
// Then, it creates a local counter for each processing operation to track the results for the entire batch.
var operationTasks = new List <Task <OperationCounters> >();
foreach (var messageGroup in messages.GroupBy(GetProcessingIndex))
{
var eventProcessingBlock = _eventProcessingBlocks[messageGroup.Key];
var input = new ProcessEventsInput(state, messageGroup);
bool success = await eventProcessingBlock.SendAsync(input);
if (!success)
{
// NOTE: This case should not actually occur.
// Complete the operation in case we couldn't send to the action block to prevent pending event queue from getting backlogged.
input.Complete();
return(new SendToActionBlockResult("Failed to add message to an action block."));
}
}
return(new SendToActionBlockResult(operationTasks));
}
}