Connection Improvements¶

As describen in the DNS topic, it's now possible to prefetch and cache DNS queries on startup, long before the first user interaction; to reduce the first request-response roundtrip faster.

But there's a new tcp connection logic too, that comes after the DNS query. The old one went over the IP addresses the DNS query returned with one-by-one. If the first one was slow to connect and took up the whole time the request allowed, then it got timed out, failing the whole request, evven thought there would be a working and fast tcp connection to another IP address.

To resolve this issue, and even improve on the connection speed in v3, if there are multiple addresses it will try to connect to a maximum of 4 (by default, it's configurable) at once and pick the fastest connecting one! Those addresses that fail to connect are marked as such, and if there's a need for a new connection, those IP addresses will be tried last.

Another new feature is that custom IP address shuffling algorithms can be added and implemented.

High-Level Flow¶

Here's a high-level view about the algorithm:

graph TD
    Start(Start)
    Start --> A

    subgraph _start [DNS & TCP Connection]

        subgraph DNS [DNSCache]
            A(Query/Prefetch) --> B(Check DNS Cache)
            B -->|Cache Hit| L[Return Cached Entry]
            B -->|Cache Miss| C(DNS Query)
            C --> D[Cache DNS Result]
            D --> L[Return Cached Entry]
        end

        subgraph Connect [TCP Connection Logic]
            F{Are there multiple IP addresses?} -->|Yes| M
            M[Shuffle Addresses] --> G
            F -->|No| H[Single Connection Attempt]
            G[Parallel Connection Attempts] --> Q
            G[Parallel Connection Attempts] --> Q
            G[Parallel Connection Attempts] --> Q
            G[Parallel Connection Attempts] --> Q
            Q{"Connection Success?"} -->|Yes| J
            Q -->|No| K
            N{Has More Address?} -->|Yes| I
            H --> Q
            J["Select First (Fastest) Connection"]
            K[Mark IP Failure] --> N
            I[Try Next IP Address] --> Q
        end

    end

    L --> F
    J --> NEG
    N -->|No| NEG

    subgraph NEG ["Further Connection/Negotiation Process"]
        Failure
        Success
    end

Code Examples¶

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Best.HTTP.Shared.HTTPManager.PerHostSettings.Get("example.com")
                .TCPRingmasterSettings.ShuffleAddresses = false;

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Best.HTTP.Shared.HTTPManager.PerHostSettings.Get("*")
                .TCPRingmasterSettings.ShuffleAddresses = false;

More about how to use PerHostSettings can be found under the Per-Host Settings topic.

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Best.HTTP.Shared.HTTPManager.PerHostSettings.Get("example.com")
                .TCPRingmasterSettings.CustomAddressShuffleAlgorithm 
                    = (@params) =>
                    {
                        var rand = new System.Random();
                        int n = @params.Addresses.Length;
                        while (n > 1)
                        {
                            int k = rand.Next(n--);
                            (@params.Addresses[n], @params.Addresses[k]) = (@params.Addresses[k], @params.Addresses[n]);
                        }
                    };

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var settings = Best.HTTP.Shared.HTTPManager.PerHostSettings.Get("example.com");
            settings.TCPRingmasterSettings.MaxSimultaneousRacers = 1;
            settings.TCPRingmasterSettings.ShuffleAddresses = false;

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