public async Task Receive()
{
try
{
using (ITransaction tx = stateManager.CreateTransaction())
{
ConditionalValue <string> offsetResult = await offsetDictionary.TryGetValueAsync(tx, "offset", LockMode.Default);
ConditionalValue <long> epochResult = await epochDictionary.TryGetValueAsync(tx, "epoch", LockMode.Update);
long newEpoch = epochResult.HasValue ? epochResult.Value + 1 : 0;
await epochDictionary.SetAsync(tx, "epoch", newEpoch);
PartitionReceiver partitionReceiver;
if (offsetResult.HasValue)
{
partitionReceiver = eventHubClient.CreateEpochReceiver(PartitionReceiver.DefaultConsumerGroupName,
"3", //Convert.ToString(this.servicePartitionKey),
offsetResult.Value,
newEpoch);
}
else
{
partitionReceiver = eventHubClient.CreateEpochReceiver(PartitionReceiver.DefaultConsumerGroupName,
Convert.ToString(this.servicePartitionKey),
"-1",
newEpoch);
}
ServiceEventSource.Current.ServiceMessage(this.serviceContext,
$"Partition Id: {servicePartitionKey}; offset: {offsetResult.Value}; Epoch: {newEpoch}");
var ehEvents = await partitionReceiver.ReceiveAsync(1);
await GenerateActors(ehEvents, tx);
await tx.CommitAsync();
}
}
catch (EventHubsException ex)
{
ServiceEventSource.Current.ServiceMessage(this.serviceContext, ex.Message);
}
catch (Exception ex)
{
ServiceEventSource.Current.ServiceMessage(this.serviceContext, ex.Message);
}
}
/// <summary>
/// Creates an PartitionReceiver from the given connection sting and partition key.
/// The Reliable Dictionaries are used to create a receiver from wherever the service last left off,
/// or from the current date/time if it's the first time the service is coming up.
/// </summary>
/// <param name="client"></param>
/// <param name="consumerGroup"></param>
/// <param name="servicePartitionKey"></param>
/// <param name="epochDictionary"></param>
/// <param name="offsetDictionary"></param>
/// <returns>PartitionReceiver</returns>
private async Task <PartitionReceiver> ConnectToIoTHubAsync(
EventHubClient client,
string consumerGroup,
long servicePartitionKey,
IReliableDictionary <string, long> epochDictionary,
IReliableDictionary <string, string> offsetDictionary)
{
// This gives each partition its own dedicated TCP connection to IoT Hub.
var eventHubRuntimeInfo = await client.GetRuntimeInformationAsync();
PartitionReceiver partitionReceiver;
// Get an IoT Hub partition ID that corresponds to this partition's low key.
// This assumes that this service has a partition count 'n' that is equal to the IoT Hub partition count and a partition range of 0..n-1.
// For example, given an IoT Hub with 32 partitions, this service should be created with:
// partition count = 32
// partition range = 0..31
string eventHubPartitionId = eventHubRuntimeInfo.PartitionIds[servicePartitionKey];
using (var tx = this.StateManager.CreateTransaction())
{
ConditionalValue <string> offsetResult = await offsetDictionary.TryGetValueAsync(tx, "offset", LockMode.Default);
ConditionalValue <long> epochResult = await epochDictionary.TryGetValueAsync(tx, "epoch", LockMode.Update);
long newEpoch = epochResult.HasValue
? epochResult.Value + 1
: 0;
if (offsetResult.HasValue)
{
// continue where the service left off before the last failover or restart.
ServiceEventSource.Current.ServiceMessage(
this.Context,
"Creating EventHub listener on partition {0} with offset {1}",
eventHubPartitionId,
offsetResult.Value);
partitionReceiver = client.CreateEpochReceiver(consumerGroup, eventHubPartitionId, EventPosition.FromOffset(offsetResult.Value), newEpoch);
}
else
{
// first time this service is running so there is no offset value yet.
// start with the current time.
ServiceEventSource.Current.ServiceMessage(
this.Context,
"Creating EventHub listener on partition {0} with offset {1}",
eventHubPartitionId,
DateTime.UtcNow);
partitionReceiver = client.CreateEpochReceiver(consumerGroup, eventHubPartitionId, EventPosition.FromEnqueuedTime(DateTime.UtcNow), newEpoch);
}
// epoch is recorded each time the service fails over or restarts.
await epochDictionary.SetAsync(tx, "epoch", newEpoch);
await tx.CommitAsync();
}
return(partitionReceiver);
}
