async Task <List <string> > PrepareTopicHashSubscriptions(TopicHashSelector selector)
{
Dictionary <string, List <string> > topicsByPublisher;
Dictionary <string, List <string> > singleWildcardTopicsByPublisher;
Dictionary <string, List <string> > multiWildcardTopicsByPublisher;
const int NumPublishers = 1;
const int NumTopicsPerPublisher = 10000;
TopicGenerator.Generate(NumPublishers, NumTopicsPerPublisher, out topicsByPublisher, out singleWildcardTopicsByPublisher, out multiWildcardTopicsByPublisher);
var topics = topicsByPublisher.FirstOrDefault().Value;
var singleWildcardTopics = singleWildcardTopicsByPublisher.FirstOrDefault().Value;
var multiWildcardTopics = multiWildcardTopicsByPublisher.FirstOrDefault().Value;
const string ClientId = "Client1";
var logger = new Mockups.TestLogger();
var serverOptions = new MQTTnet.Server.MqttServerOptions();
var eventContainer = new MQTTnet.Server.MqttServerEventContainer();
var retainedMessagesManager = new MqttRetainedMessagesManager(eventContainer, logger);
var sessionManager = new MqttClientSessionsManager(serverOptions, retainedMessagesManager, eventContainer, logger);
_clientSession = new MQTTnet.Server.MqttSession(
ClientId,
false,
new Dictionary <object, object>(),
serverOptions,
eventContainer,
retainedMessagesManager,
sessionManager
);
List <string> topicsToSubscribe;
switch (selector)
{
case TopicHashSelector.SingleWildcard:
topicsToSubscribe = singleWildcardTopics;
break;
case TopicHashSelector.MultiWildcard:
topicsToSubscribe = multiWildcardTopics;
break;
default:
topicsToSubscribe = topics;
break;
}
foreach (var t in topicsToSubscribe)
{
var subPacket = new Packets.MqttSubscribePacket();
var filter = new Packets.MqttTopicFilter();
filter.Topic = t;
subPacket.TopicFilters.Add(filter);
await _clientSession.SubscriptionsManager.Subscribe(subPacket, default(CancellationToken));
}
return(topics);
}
public void Check_Hash_Bucket_Depth()
{
Dictionary <string, List <string> > topicsByPublisher;
Dictionary <string, List <string> > singleWildcardTopicsByPublisher;
Dictionary <string, List <string> > multiWildcardTopicsByPublisher;
const int NumPublishers = 5000;
const int NumTopicsPerPublisher = 10;
TopicGenerator.Generate(NumPublishers, NumTopicsPerPublisher, out topicsByPublisher, out singleWildcardTopicsByPublisher, out multiWildcardTopicsByPublisher);
// There will be many 'similar' topics ending with, i.e. "sensor100", "sensor101", ...
// Hash bucket depths should remain low.
var bucketDepths = new Dictionary <UInt64, int>();
int maxBucketDepth = 0;
UInt64 maxBucketDepthHash = 0;
var topicsByHash = new Dictionary <UInt64, List <string> >();
foreach (var t in topicsByPublisher)
{
var topics = t.Value;
foreach (var topic in topics)
{
UInt64 topicHash;
UInt64 hashMask;
bool hasWildcard;
MQTTnet.Server.MqttSubscription.CalculateTopicHash(topic, out topicHash, out hashMask, out hasWildcard);
bucketDepths.TryGetValue(topicHash, out var currentValue);
++currentValue;
bucketDepths[topicHash] = currentValue;
if (currentValue > maxBucketDepth)
{
maxBucketDepth = currentValue;
maxBucketDepthHash = topicHash;
}
if (!topicsByHash.TryGetValue(topicHash, out var topicList))
{
topicList = new List <string>();
topicsByHash.Add(topicHash, topicList);
}
topicList.Add(topic);
}
}
var maxDepthTopics = topicsByHash[maxBucketDepthHash];
Console.Write("Max bucket depth is " + maxBucketDepth);
// for the test case the bucket depth should be less than 100
Assert.IsTrue(maxBucketDepth < 100, "Unexpected high topic hash bucket depth");
}
