RedirectToHttpsRule: opportunity for performance improvement

[paulomorgado]

Summary

While debugging some code, I noticed that RedirectToHttpsRule is instantiating a StringBuilder and boxing structs on every request.

Motivation and goals

This is in a hot path for applications that use redirection to HTTPS.

Detailed design

Most uses of HostString, PathString and QueryString use ToString() or ToUriComponent() to avoid boxing. This is not the case for RedirectToHttpsRule:

new StringBuilder().Append("https://").Append(host).Append(req.PathBase).Append(req.Path).Append(req.QueryString);

So, I started playing with options:

[MemoryDiagnoser]
public class Benchmark
{
    private static readonly string[] hosts = new[] { "cname.domain.tld" };
    private static readonly string[] basePaths = new[] { null, "/base-path", };
    private static readonly string[] paths = new[] { "/", "/path/one/two/three", };
    private static readonly string[] queries = new[] { null, "?param1=value1&param2=value2&param3=value3", };

    public IEnumerable<object[]> Data()
    {
        foreach (var host in hosts)
        {
            foreach (var basePath in basePaths)
            {
                foreach (var path in paths)
                {
                    foreach (var query in queries)
                    {
                        yield return new object[] { new HostString(host), new PathString(basePath), new PathString(path), new QueryString(query), };
                    }
                }
            }
        }
    }

    [Benchmark(Baseline = true)]
    [ArgumentsSource(nameof(Data))]
    public string StringBuilderWithBoxing(HostString host, PathString basePath, PathString path, QueryString query)
        => new StringBuilder()
            .Append("https://")
            .Append(host)
            .Append(basePath)
            .Append(path)
            .Append(query)
            .ToString();

    [Benchmark]
    [ArgumentsSource(nameof(Data))]
    public string StringBuilderWithoutBoxing(HostString host, PathString basePath, PathString path, QueryString query)
        => new StringBuilder()
            .Append("https://")
            .Append(host.ToUriComponent())
            .Append(basePath.ToUriComponent())
            .Append(path.ToUriComponent())
            .Append(query.ToUriComponent())
        .ToString();

    [Benchmark]
    [ArgumentsSource(nameof(Data))]
    public string StringFormatWithBoxing(HostString host, PathString basePath, PathString path, QueryString query)
        => $"https://{host}{basePath}{path}{query}";

    [Benchmark]
    [ArgumentsSource(nameof(Data))]
    public string StringFormatWithoutBoxing(HostString host, PathString basePath, PathString path, QueryString query)
        => $"https://{host.ToUriComponent()}{basePath.ToUriComponent()}{path.ToUriComponent()}{query.ToUriComponent()}";

    [Benchmark]
    [ArgumentsSource(nameof(Data))]
    public string StringConcat(HostString host, PathString basePath, PathString path, QueryString query)
    {
        if (!basePath.HasValue)
        {
            return string.Concat("https://", host, path.ToUriComponent(), query.ToUriComponent());
        }

        if (!query.HasValue)
        {
            return string.Concat("https://", host, basePath.ToUriComponent(), path.ToUriComponent());
        }

        return string.Concat("https://", host, basePath.ToUriComponent(), path.ToUriComponent(), query.ToUriComponent());
    }

    [Benchmark]
    [ArgumentsSource(nameof(Data))]
    public string Crazy1(HostString host, PathString basePath, PathString path, QueryString query)
    {
        var uriParts = (
            scheme: "https://",
            host: host.ToUriComponent(),
            basePath: basePath.ToUriComponent(),
            path: path.ToUriComponent(),
            query: query.ToUriComponent());

        var length = uriParts.scheme.Length + uriParts.host.Length + uriParts.basePath.Length + uriParts.path.Length + uriParts.query.Length;

        return string.Create(
            length,
            uriParts,
            (buffer, uriParts) =>
            {
                var i = -1;

                foreach (var c in uriParts.scheme)
                {
                    buffer[++i] = c;
                }

                foreach (var c in uriParts.host)
                {
                    buffer[++i] = c;
                }

                if (uriParts.basePath.Length != 0)
                {
                    foreach (var c in uriParts.basePath)
                    {
                        buffer[++i] = c;
                    }
                }

                foreach (var c in uriParts.path)
                {
                    buffer[++i] = c;
                }

                if (uriParts.query.Length != 0)
                {
                    foreach (var c in uriParts.query)
                    {
                        buffer[++i] = c;
                    }
                }
            });
    }

    [Benchmark]
    [ArgumentsSource(nameof(Data))]
    public string Crazy2(HostString host, PathString basePath, PathString path, QueryString query)
    {
        const string httpsSchemePrefix = "https://";
        const int httpsSchemePrefixLength = 8;
        Debug.Assert(httpsSchemePrefix.Length == httpsSchemePrefixLength, "{nameof(httpsSchemePrefixLength)} should be {httpsSchemePrefix.Length} and is {httpsSchemePrefixLength}");

        var uriParts = (
            host: host.ToUriComponent(),
            basePath: basePath.ToUriComponent(),
            path: path.ToUriComponent(),
            query: query.ToUriComponent());

        var length = httpsSchemePrefixLength + uriParts.host.Length + uriParts.basePath.Length + uriParts.path.Length + uriParts.query.Length;

        return string.Create(
            length,
            uriParts,
            (buffer, uriParts) =>
            {
                var span = httpsSchemePrefix.AsSpan();
                span.CopyTo(buffer);

                var i = httpsSchemePrefixLength;

                span = uriParts.host.AsSpan();
                span.CopyTo(buffer.Slice(i, span.Length));
                i += span.Length;

                if (uriParts.basePath.Length != 0)
                {
                    span = uriParts.basePath.AsSpan();
                    span.CopyTo(buffer.Slice(i, span.Length));
                    i += span.Length;
                }

                span = uriParts.path.AsSpan();
                span.CopyTo(buffer.Slice(i, span.Length));
                i += span.Length;

                if (uriParts.query.Length != 0)
                {
                    span = uriParts.query.AsSpan();
                    span.CopyTo(buffer.Slice(i, span.Length));
                }
            });
    }
}

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.21277
Intel Core i7-8650U CPU 1.90GHz (Kaby Lake R), 1 CPU, 8 logical and 4 physical cores
.NET Core SDK=5.0.200-preview.20614.14
[Host] : .NET Core 5.0.1 (CoreCLR 5.0.120.57516, CoreFX 5.0.120.57516), X64 RyuJIT
DefaultJob : .NET Core 5.0.1 (CoreCLR 5.0.120.57516, CoreFX 5.0.120.57516), X64 RyuJIT

Method	host	basePath	path	query	Mean	Error	StdDev	Median	Ratio	RatioSD	Gen 0	Gen 1	Gen 2	Allocated
StringBuilderWithBoxing	cname.domain.tld		/		382.9 ns	38.31 ns	112.95 ns	369.1 ns	1.00	0.00	0.0782	-	-	328 B
StringBuilderWithoutBoxing	cname.domain.tld		/		304.8 ns	23.13 ns	68.19 ns	296.4 ns	0.84	0.24	0.0668	-	-	280 B
StringFormatWithBoxing	cname.domain.tld		/		495.3 ns	43.01 ns	126.83 ns	483.5 ns	1.43	0.59	0.0534	-	-	224 B
StringFormatWithoutBoxing	cname.domain.tld		/		147.4 ns	7.46 ns	21.41 ns	140.6 ns	0.42	0.11	0.0324	-	-	136 B
StringConcat	cname.domain.tld		/		220.3 ns	14.88 ns	42.94 ns	212.0 ns	0.65	0.26	0.0496	-	-	208 B
Crazy1	cname.domain.tld		/		145.2 ns	8.58 ns	24.90 ns	138.5 ns	0.42	0.15	0.0172	-	-	72 B
Crazy2	cname.domain.tld		/		133.6 ns	7.20 ns	20.67 ns	126.7 ns	0.39	0.15	0.0172	-	-	72 B
StringBuilderWithBoxing	cname.domain.tld		/	?para(...)alue3 [42]	400.0 ns	18.60 ns	53.95 ns	392.5 ns	1.00	0.00	0.1335	-	-	560 B
StringBuilderWithoutBoxing	cname.domain.tld		/	?para(...)alue3 [42]	408.3 ns	20.84 ns	60.80 ns	401.0 ns	1.04	0.20	0.1221	-	-	512 B
StringFormatWithBoxing	cname.domain.tld		/	?para(...)alue3 [42]	455.5 ns	19.01 ns	54.86 ns	438.0 ns	1.16	0.21	0.0744	-	-	312 B
StringFormatWithoutBoxing	cname.domain.tld		/	?para(...)alue3 [42]	253.8 ns	15.62 ns	45.33 ns	238.8 ns	0.65	0.15	0.0534	-	-	224 B
StringConcat	cname.domain.tld		/	?para(...)alue3 [42]	261.8 ns	9.77 ns	28.35 ns	249.8 ns	0.67	0.12	0.0706	-	-	296 B
Crazy1	cname.domain.tld		/	?para(...)alue3 [42]	261.8 ns	11.49 ns	33.53 ns	256.8 ns	0.67	0.13	0.0381	-	-	160 B
Crazy2	cname.domain.tld		/	?para(...)alue3 [42]	191.9 ns	6.41 ns	17.86 ns	188.1 ns	0.49	0.07	0.0381	-	-	160 B
StringBuilderWithBoxing	cname.domain.tld		/path/one/two/three		515.1 ns	26.82 ns	78.23 ns	494.3 ns	1.00	0.00	0.1202	-	-	504 B
StringBuilderWithoutBoxing	cname.domain.tld		/path/one/two/three		420.0 ns	12.85 ns	36.46 ns	408.7 ns	0.83	0.13	0.1087	-	-	456 B
StringFormatWithBoxing	cname.domain.tld		/path/one/two/three		603.6 ns	36.37 ns	105.50 ns	587.3 ns	1.19	0.23	0.0629	-	-	264 B
StringFormatWithoutBoxing	cname.domain.tld		/path/one/two/three		285.5 ns	8.47 ns	24.04 ns	278.8 ns	0.56	0.09	0.0420	-	-	176 B
StringConcat	cname.domain.tld		/path/one/two/three		364.6 ns	14.04 ns	41.41 ns	356.2 ns	0.72	0.13	0.0591	-	-	248 B
Crazy1	cname.domain.tld		/path/one/two/three		277.0 ns	5.65 ns	14.19 ns	273.2 ns	0.56	0.08	0.0267	-	-	112 B
Crazy2	cname.domain.tld		/path/one/two/three		272.4 ns	6.98 ns	19.92 ns	264.9 ns	0.54	0.09	0.0267	-	-	112 B
StringBuilderWithBoxing	cname.domain.tld		/path/one/two/three	?para(...)alue3 [42]	618.1 ns	27.22 ns	78.54 ns	600.5 ns	1.00	0.00	0.1869	-	-	784 B
StringBuilderWithoutBoxing	cname.domain.tld		/path/one/two/three	?para(...)alue3 [42]	555.5 ns	11.16 ns	29.20 ns	546.8 ns	0.92	0.10	0.1755	-	-	736 B
StringFormatWithBoxing	cname.domain.tld		/path/one/two/three	?para(...)alue3 [42]	656.4 ns	33.39 ns	96.88 ns	621.5 ns	1.08	0.21	0.0820	-	-	344 B
StringFormatWithoutBoxing	cname.domain.tld		/path/one/two/three	?para(...)alue3 [42]	413.8 ns	21.86 ns	62.71 ns	393.0 ns	0.68	0.11	0.0610	-	-	256 B
StringConcat	cname.domain.tld		/path/one/two/three	?para(...)alue3 [42]	456.0 ns	19.25 ns	55.84 ns	446.0 ns	0.75	0.12	0.0782	-	-	328 B
Crazy1	cname.domain.tld		/path/one/two/three	?para(...)alue3 [42]	407.0 ns	11.24 ns	31.52 ns	396.5 ns	0.67	0.08	0.0458	-	-	192 B
Crazy2	cname.domain.tld		/path/one/two/three	?para(...)alue3 [42]	376.2 ns	16.68 ns	48.40 ns	361.1 ns	0.62	0.10	0.0458	-	-	192 B
StringBuilderWithBoxing	cname.domain.tld	/base-path	/		390.5 ns	15.75 ns	46.21 ns	375.9 ns	1.00	0.00	0.1163	-	-	488 B
StringBuilderWithoutBoxing	cname.domain.tld	/base-path	/		380.4 ns	15.97 ns	45.56 ns	372.0 ns	0.99	0.16	0.1049	-	-	440 B
StringFormatWithBoxing	cname.domain.tld	/base-path	/		499.0 ns	32.56 ns	92.36 ns	472.7 ns	1.30	0.27	0.0591	-	-	248 B
StringFormatWithoutBoxing	cname.domain.tld	/base-path	/		258.8 ns	11.54 ns	33.67 ns	255.7 ns	0.67	0.11	0.0381	-	-	160 B
StringConcat	cname.domain.tld	/base-path	/		249.8 ns	6.38 ns	17.90 ns	246.0 ns	0.65	0.07	0.0553	-	-	232 B
Crazy1	cname.domain.tld	/base-path	/		202.6 ns	4.14 ns	6.56 ns	200.1 ns	0.52	0.06	0.0229	-	-	96 B
Crazy2	cname.domain.tld	/base-path	/		200.9 ns	8.15 ns	23.63 ns	194.8 ns	0.52	0.08	0.0229	-	-	96 B
StringBuilderWithBoxing	cname.domain.tld	/base-path	/	?para(...)alue3 [42]	556.7 ns	31.99 ns	91.78 ns	534.3 ns	1.00	0.00	0.1831	-	-	768 B
StringBuilderWithoutBoxing	cname.domain.tld	/base-path	/	?para(...)alue3 [42]	502.9 ns	20.48 ns	56.42 ns	484.2 ns	0.92	0.17	0.1717	-	-	720 B
StringFormatWithBoxing	cname.domain.tld	/base-path	/	?para(...)alue3 [42]	586.8 ns	43.96 ns	126.82 ns	540.6 ns	1.09	0.31	0.0782	-	-	328 B
StringFormatWithoutBoxing	cname.domain.tld	/base-path	/	?para(...)alue3 [42]	429.7 ns	35.01 ns	103.24 ns	382.2 ns	0.80	0.24	0.0572	-	-	240 B
StringConcat	cname.domain.tld	/base-path	/	?para(...)alue3 [42]	360.8 ns	8.61 ns	24.30 ns	359.3 ns	0.66	0.11	0.0782	-	-	328 B
Crazy1	cname.domain.tld	/base-path	/	?para(...)alue3 [42]	391.9 ns	32.32 ns	95.28 ns	349.5 ns	0.72	0.19	0.0420	-	-	176 B
Crazy2	cname.domain.tld	/base-path	/	?para(...)alue3 [42]	262.8 ns	5.18 ns	10.23 ns	259.4 ns	0.51	0.07	0.0420	-	-	176 B
StringBuilderWithBoxing	cname.domain.tld	/base-path	/path/one/two/three		636.3 ns	53.84 ns	158.75 ns	565.9 ns	1.00	0.00	0.1240	-	-	520 B
StringBuilderWithoutBoxing	cname.domain.tld	/base-path	/path/one/two/three		623.6 ns	46.91 ns	133.84 ns	584.1 ns	1.07	0.35	0.1125	-	-	472 B
StringFormatWithBoxing	cname.domain.tld	/base-path	/path/one/two/three		611.5 ns	16.20 ns	45.96 ns	595.5 ns	1.04	0.23	0.0668	-	-	280 B
StringFormatWithoutBoxing	cname.domain.tld	/base-path	/path/one/two/three		365.9 ns	12.68 ns	34.93 ns	353.5 ns	0.63	0.10	0.0458	-	-	192 B
StringConcat	cname.domain.tld	/base-path	/path/one/two/three		494.8 ns	40.47 ns	119.34 ns	485.9 ns	0.82	0.27	0.0629	-	-	264 B
Crazy1	cname.domain.tld	/base-path	/path/one/two/three		356.8 ns	6.76 ns	17.69 ns	350.8 ns	0.63	0.11	0.0305	-	-	128 B
Crazy2	cname.domain.tld	/base-path	/path/one/two/three		374.2 ns	19.14 ns	54.91 ns	356.5 ns	0.62	0.13	0.0305	-	-	128 B
StringBuilderWithBoxing	cname.domain.tld	/base-path	/path/one/two/three	?para(...)alue3 [42]	900.7 ns	75.84 ns	223.62 ns	808.0 ns	1.00	0.00	0.1926	-	-	808 B
StringBuilderWithoutBoxing	cname.domain.tld	/base-path	/path/one/two/three	?para(...)alue3 [42]	700.5 ns	41.28 ns	119.75 ns	646.0 ns	0.82	0.24	0.1812	-	-	760 B
StringFormatWithBoxing	cname.domain.tld	/base-path	/path/one/two/three	?para(...)alue3 [42]	1,013.9 ns	73.98 ns	218.14 ns	1,015.0 ns	1.21	0.43	0.0877	-	-	368 B
StringFormatWithoutBoxing	cname.domain.tld	/base-path	/path/one/two/three	?para(...)alue3 [42]	484.2 ns	21.74 ns	60.24 ns	469.1 ns	0.56	0.14	0.0668	-	-	280 B
StringConcat	cname.domain.tld	/base-path	/path/one/two/three	?para(...)alue3 [42]	725.7 ns	59.97 ns	176.81 ns	728.3 ns	0.86	0.32	0.0877	-	-	368 B
Crazy1	cname.domain.tld	/base-path	/path/one/two/three	?para(...)alue3 [42]	643.1 ns	53.89 ns	158.89 ns	579.0 ns	0.77	0.30	0.0515	-	-	216 B
Crazy2	cname.domain.tld	/base-path	/path/one/two/three	?para(...)alue3 [42]	406.6 ns	6.35 ns	10.78 ns	405.9 ns	0.36	0.06	0.0515	-	-	216 B

• As the table shows, and, as expect, boxing cause more memory to be allocated than not boxing.
• Using string.Concat, as it is, is not always faster or allocates less memory than using string.Format without boxing.
• The Crazy options are always faster and use allocate less memory. Crazy2 is the fastest option.

[Tratcher]

RedirectToHttpsRule should be updated to use UriHelper.BuildAbsolute and we can focus any optimization efforts over there. It already has a few improvements over this code.

[paulomorgado]

Yes! And I'm working on a proposal to improve the performance of that too.

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[paulomorgado]

I think this could also be improvde:

if (SSLPort.HasValue && SSLPort.Value > 0)
{
    // a specific SSL port is specified
    host = new HostString(host.Host, SSLPort.Value);
}
else
{
    // clear the port
    host = new HostString(host.Host);
}

If the `SSLPort was sanitized in a constructor:

public RedirectToHttpsRule(int statusCode, int? sslPort)
{
    StatusCode = statusCode;
    SSLPort = (sslPort.HasValue && sslPort.GetValueOrDefault() > 0) ? sslPort.GetValueOrDefault() : 0;
}

public int StatusCode{ get; }
public int SSLPort { get; }

That code could become:

if (SSLPort > 0)
{
    // a specific SSL port is specified
    host = new HostString(host.Host, SSLPort);
}
else
{
    // clear the port
    host = new HostString(host.Host);
}

Less memory used and less processing time.

[paulomorgado]

Are there any unit tests for this? If so, where?

[paulomorgado]

Found! MiddlewareTests.cs