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Async consumer #58

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2c255c8
use await Task.Delay instead of Thread.Sleep inside an async Task
buybackoff May 3, 2015
08f04e6
use AsyncCollection in Consumer
buybackoff May 3, 2015
7c44e7e
add a simple test for ConsumeNextAsync
buybackoff May 3, 2015
52770eb
remove await in catch block
buybackoff May 3, 2015
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28 changes: 19 additions & 9 deletions src/kafka-net/Common/AsyncCollection.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,12 +10,22 @@ public class AsyncCollection<T>
{
private readonly object _lock = new object();
private readonly AsyncManualResetEvent _dataAvailableEvent = new AsyncManualResetEvent();
private readonly ConcurrentBag<T> _bag = new ConcurrentBag<T>();
private readonly IProducerConsumerCollection<T> _collection;
private long _dataInBufferCount = 0;

public int Count
public AsyncCollection()
{
_collection = new ConcurrentBag<T>();
}

public AsyncCollection(IProducerConsumerCollection<T> collection)
{
_collection = collection;
}

public int Count
{
get { return _bag.Count + (int)Interlocked.Read(ref _dataInBufferCount); }
get { return _collection.Count + (int)Interlocked.Read(ref _dataInBufferCount); }
}

public bool IsCompleted { get; private set; }
Expand All @@ -37,7 +47,7 @@ public void Add(T data)
throw new ObjectDisposedException("AsyncCollection has been marked as complete. No new documents can be added.");
}

_bag.Add(data);
_collection.TryAdd(data);
TriggerDataAvailability();
}

Expand Down Expand Up @@ -88,7 +98,7 @@ public async Task<List<T>> TakeAsync(int count, TimeSpan timeout, CancellationTo
public void DrainAndApply(Action<T> appliedFunc)
{
T data;
while (_bag.TryTake(out data))
while (_collection.TryTake(out data))
{
appliedFunc(data);
}
Expand All @@ -99,7 +109,7 @@ public void DrainAndApply(Action<T> appliedFunc)
public IEnumerable<T> Drain()
{
T data;
while (_bag.TryTake(out data))
while (_collection.TryTake(out data))
{
yield return data;
}
Expand All @@ -111,19 +121,19 @@ public bool TryTake(out T data)
{
try
{
return _bag.TryTake(out data);
return _collection.TryTake(out data);
}
finally
{
if (_bag.IsEmpty) TriggerDataAvailability();
if (_collection.Count == 0) TriggerDataAvailability();
}
}

private void TriggerDataAvailability()
{
lock (_lock)
{
if (_bag.IsEmpty)
if (_collection.Count == 0)
{
_dataAvailableEvent.Reset();
}
Expand Down
80 changes: 69 additions & 11 deletions src/kafka-net/Consumer.cs
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Original file line number Diff line number Diff line change
@@ -1,9 +1,11 @@
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using KafkaNet.Common;
using KafkaNet.Model;
using KafkaNet.Protocol;

Expand All @@ -18,7 +20,8 @@ namespace KafkaNet
public class Consumer : IMetadataQueries, IDisposable
{
private readonly ConsumerOptions _options;
private readonly BlockingCollection<Message> _fetchResponseQueue;
private readonly AsyncCollection<Message> _fetchResponseCollection;
private readonly SemaphoreSlim _boundedCapacitySemaphore;
private readonly CancellationTokenSource _disposeToken = new CancellationTokenSource();
private readonly ConcurrentDictionary<int, Task> _partitionPollingIndex = new ConcurrentDictionary<int, Task>();
private readonly ConcurrentDictionary<int, long> _partitionOffsetIndex = new ConcurrentDictionary<int, long>();
Expand All @@ -31,9 +34,10 @@ public class Consumer : IMetadataQueries, IDisposable
public Consumer(ConsumerOptions options, params OffsetPosition[] positions)
{
_options = options;
_fetchResponseQueue = new BlockingCollection<Message>(_options.ConsumerBufferSize);
_fetchResponseCollection = new AsyncCollection<Message>(new ConcurrentQueue<Message>());
_boundedCapacitySemaphore = new SemaphoreSlim(_options.ConsumerBufferSize, _options.ConsumerBufferSize);
_metadataQueries = new MetadataQueries(_options.Router);

SetOffsetPosition(positions);
}

Expand All @@ -50,7 +54,60 @@ public IEnumerable<Message> Consume(CancellationToken? cancellationToken = null)
{
_options.Log.DebugFormat("Consumer: Beginning consumption of topic: {0}", _options.Topic);
EnsurePartitionPollingThreads();
return _fetchResponseQueue.GetConsumingEnumerable(cancellationToken ?? CancellationToken.None);
// need a separate method with yield, otherwise EnsurePartitionPollingThreads() is not called until enumeration, e.g. ToArray()
return DoConsume(cancellationToken);
}

private IEnumerable<Message> DoConsume(CancellationToken? cancellationToken = null)
{
while (true)
{
try
{
// blocking wait for data
_fetchResponseCollection.OnHasDataAvailable(cancellationToken ?? CancellationToken.None).Wait();
}
catch (AggregateException e)
{
if (e.InnerException is TaskCanceledException)
{
throw new OperationCanceledException();
}
throw;
}
Message data;
// do not call OnHasDataAvailable if data is available
while (_fetchResponseCollection.TryTake(out data))
{
_boundedCapacitySemaphore.Release();
yield return data;
}
}
}


public async Task<Message> ConsumeNextAsync()
{
return await ConsumeNextAsync(new TimeSpan(int.MaxValue), CancellationToken.None);
}

/// <summary>
/// Pull a next message for consumption asynchronously
/// </summary>
public async Task<Message> ConsumeNextAsync(TimeSpan timeout, CancellationToken token)
{
// this will only iterlocked.increment/decrement(_ensureOneThread) and compare to 1 on each call
EnsurePartitionPollingThreads();

if (_fetchResponseCollection.IsCompleted)
{
var tcs = new TaskCompletionSource<Message>();
tcs.SetCanceled();
return await tcs.Task;
}
var result = (await _fetchResponseCollection.TakeAsync(1, timeout, token)).Single();
_boundedCapacitySemaphore.Release();
return result;
}

/// <summary>
Expand Down Expand Up @@ -139,11 +196,11 @@ private Task ConsumeTopicPartitionAsync(string topic, int partitionId)
var fetches = new List<Fetch> { fetch };

var fetchRequest = new FetchRequest
{
MaxWaitTime = (int)Math.Min((long)int.MaxValue, _options.MaxWaitTimeForMinimumBytes.TotalMilliseconds),
MinBytes = _options.MinimumBytes,
Fetches = fetches
};
{
MaxWaitTime = (int)Math.Min((long)int.MaxValue, _options.MaxWaitTimeForMinimumBytes.TotalMilliseconds),
MinBytes = _options.MinimumBytes,
Fetches = fetches
};

//make request and post to queue
var route = _options.Router.SelectBrokerRoute(topic, partitionId);
Expand All @@ -160,7 +217,8 @@ private Task ConsumeTopicPartitionAsync(string topic, int partitionId)

foreach (var message in response.Messages)
{
_fetchResponseQueue.Add(message, _disposeToken.Token);
await _boundedCapacitySemaphore.WaitAsync(_disposeToken.Token);
_fetchResponseCollection.Add(message);

if (_disposeToken.IsCancellationRequested) return;
}
Expand All @@ -174,7 +232,7 @@ private Task ConsumeTopicPartitionAsync(string topic, int partitionId)
}

//no message received from server wait a while before we try another long poll
Thread.Sleep(_options.BackoffInterval);
await Task.Delay(_options.BackoffInterval);
}
catch (BufferUnderRunException ex)
{
Expand Down
38 changes: 38 additions & 0 deletions src/kafka-tests/Integration/ProducerConsumerIntegrationTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,44 @@ public void ConsumerShouldConsumeInSameOrderAsProduced()
}
}


[Test]
public void AsyncConsumerShouldConsumeInSameOrderAsProduced()
{
var expected = new List<string> { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19" };
var testId = Guid.NewGuid().ToString();

using (var router = new BrokerRouter(new KafkaOptions(IntegrationConfig.IntegrationUri)))
using (var producer = new Producer(router))
{

var offsets = producer.GetTopicOffsetAsync(IntegrationConfig.IntegrationTopic).Result;

using (var consumer = new Consumer(new ConsumerOptions(IntegrationConfig.IntegrationTopic, router),
offsets.Select(x => new OffsetPosition(x.PartitionId, x.Offsets.Max())).ToArray()))
{

for (int i = 0; i < 20; i++)
{
producer.SendMessageAsync(IntegrationConfig.IntegrationTopic, new[] { new Message(i.ToString(), testId) }).Wait();
}
List<Message> results = new List<Message>();

for (int i = 0; i < 20; i++)
{
results.Add(consumer.ConsumeNextAsync().Result);
}

//ensure the produced messages arrived
Console.WriteLine("Message order: {0}", string.Join(", ", results.Select(x => x.Value.ToUtf8String()).ToList()));

Assert.That(results.Count, Is.EqualTo(20));
Assert.That(results.Select(x => x.Value.ToUtf8String()).ToList(), Is.EqualTo(expected), "Expected the message list in the correct order.");
Assert.That(results.Any(x => x.Key.ToUtf8String() != testId), Is.False);
}
}
}

[Test]
public void ConsumerShouldBeAbleToSeekBackToEarlierOffset()
{
Expand Down