MQTTnet/Source/MQTTnet.Benchmarks/TopicGenerator.cs

using System;
using System.Collections.Generic;

namespace MQTTnet.Benchmarks
{
    public class TopicGenerator
    {
        public static void Generate(
            int numPublishers,
            int numTopicsPerPublisher,
            out Dictionary<string, List<string>> topicsByPublisher,
            out Dictionary<string, List<string>> singleWildcardTopicsByPublisher,
            out Dictionary<string, List<string>> multiWildcardTopicsByPublisher)
        {
            topicsByPublisher = new Dictionary<string, List<string>>();
            singleWildcardTopicsByPublisher = new Dictionary<string, List<string>>();
            multiWildcardTopicsByPublisher = new Dictionary<string, List<string>>();

            // Find some reasonable distribution across three topic levels
            var topicsPerLevel = (int)Math.Pow(numTopicsPerPublisher, 1.0 / 3.0);
            if (topicsPerLevel <= 0)
            {
                topicsPerLevel = 1;
            }

            var numLevel1Topics = topicsPerLevel;
            var numLevel2Topics = topicsPerLevel;

            var maxNumLevel3Topics = 1 + (int)((double)numTopicsPerPublisher / numLevel1Topics / numLevel2Topics);
            if (maxNumLevel3Topics <= 0)
            {
                maxNumLevel3Topics = 1;
            }

            for (var p = 0; p < numPublishers; ++p)
            {
                var publisherTopicCount = 0;
                var publisherName = "pub" + p;
                for (var l1 = 0; l1 < numLevel1Topics; ++l1)
                {
                    for (var l2 = 0; l2 < numLevel2Topics; ++l2)
                    {
                        for (var l3 = 0; l3 < maxNumLevel3Topics; ++l3)
                        {
                            if (publisherTopicCount >= numTopicsPerPublisher)
                            {
                                break;
                            }

                            var topic = $"{publisherName}/building{l1 + 1}/level{l2 + 1}/sensor{l3 + 1}";
                            AddPublisherTopic(publisherName, topic, topicsByPublisher);

                            if (l2 == 0)
                            {
                                var singleWildcardTopic = $"{publisherName}/building{l1 + 1}/+/sensor{l3 + 1}";
                                AddPublisherTopic(publisherName, singleWildcardTopic, singleWildcardTopicsByPublisher);
                            }

                            if (l1 == 0 && l3 == 0)
                            {
                                var multiWildcardTopic = $"{publisherName}/+/level{l2 + 1}/+";
                                AddPublisherTopic(publisherName, multiWildcardTopic, multiWildcardTopicsByPublisher);
                            }

                            ++publisherTopicCount;
                        }
                    }
                }
            }
        }

        static void AddPublisherTopic(string publisherName, string topic, Dictionary<string, List<string>> topicsByPublisher)
        {
            List<string> topicList;
            if (!topicsByPublisher.TryGetValue(publisherName, out topicList))
            {
                topicList = new List<string>();
                topicsByPublisher.Add(publisherName, topicList);
            }

            topicList.Add(topic);
        }
    }
}