Optimize allocations in HttpUtility.UrlDecodeToBytes for smaller inputs. #102753

TrayanZapryanov · 2024-05-28T12:00:54Z

Optimize byte[] allocation when:

input string is less than 256 chars(might change after review)
maximum encoded bytes according Encoding is less than 512(might change after review)

If a "happy" path is taken, we will have allocations equals to the returned byte[].
Drawback: method will be a bit slower as we need to calculate Encoding.GetMaxByteCount(xxx)

dotnet-policy-service · 2024-05-28T12:01:21Z

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TrayanZapryanov · 2024-05-28T12:10:11Z

Benchmark:

[MemoryDiagnoser]
public class HttpUtilityBenchmarks
{
	[Benchmark(Baseline = true)]
	public byte[] UrlDecodeToBytes() => HttpUtility.UrlDecodeToBytes("http://127.0.0.1:8080/app%%Dir/page.aspx?foo=b%%r");

	[Benchmark]
	public byte[] UrlDecodeToBytes_PR() => MyHttpUtility.UrlDecodeToBytes("http://127.0.0.1:8080/app%%Dir/page.aspx?foo=b%%r");
}

Results:

Method	Mean	Error	StdDev	Ratio	Gen0	Allocated	Alloc Ratio
UrlDecodeToBytes	90.45 ns	1.436 ns	1.343 ns	1.00	0.0191	160 B	1.00
UrlDecodeToBytes_PR	80.87 ns	0.632 ns	0.560 ns	0.89	0.0095	80 B	0.50

MihaZupan

Thank you for looking into making improvements here.
Is the existing test coverage here sufficient to catch any potential regressions?

src/libraries/System.Web.HttpUtility/src/System/Web/Util/HttpEncoder.cs

src/libraries/System.Web.HttpUtility/src/System/Web/HttpUtility.cs

src/libraries/System.Web.HttpUtility/src/System/Web/Util/HttpEncoder.cs

src/libraries/System.Web.HttpUtility/src/System/Web/HttpUtility.cs

EgorBo · 2024-05-28T13:29:08Z

@EgorBot -intel -arm64 -profiler

using BenchmarkDotNet.Attributes;
using System.Web;
using BenchmarkDotNet.Running;

BenchmarkRunner.Run<HttpUtilityBenchmarks>(args: args);

public class HttpUtilityBenchmarks
{
    [Benchmark]
    public byte[] UrlDecodeToBytes() => 
        HttpUtility.UrlDecodeToBytes(
            "http://127.0.0.1:8080/app%%Dir/page.aspx?foo=b%%r");
}

src/libraries/System.Web.HttpUtility/src/System/Web/Util/HttpEncoder.cs

EgorBot · 2024-05-28T13:42:47Z

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 16 logical and 8 physical cores
  Job-PTRDNU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  Job-JRGPMR : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
UrlDecodeToBytes	Main	128.22 ns	1.150 ns	1.00
UrlDecodeToBytes	PR	89.45 ns	0.144 ns	0.70

More data

See BDN_Artifacts.zip for details.

Flame graphs: Main vs PR 🔥
Hot asm: Main vs PR
Hot functions: Main vs PR

For clean perf results, make sure you have just one [Benchmark] in your app.

EgorBot · 2024-05-28T13:46:11Z

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
  Job-BUHYYP : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
  Job-KRDBSO : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
UrlDecodeToBytes	Main	176.4 ns	0.21 ns	1.00
UrlDecodeToBytes	PR	170.5 ns	0.15 ns	0.97

More data

See BDN_Artifacts.zip for details.

Flame graphs: Main vs PR 🔥
Hot asm: Main vs PR
Hot functions: Main vs PR

For clean perf results, make sure you have just one [Benchmark] in your app.

src/libraries/System.Web.HttpUtility/src/System/Web/HttpUtility.cs

src/libraries/System.Web.HttpUtility/src/System/Web/Util/HttpEncoder.cs

MihaZupan · 2024-05-29T16:48:00Z

src/libraries/System.Web.HttpUtility/src/System/Web/HttpUtility.cs


        [return: NotNullIfNotNull(nameof(bytes))]
-        public static byte[]? UrlDecodeToBytes(byte[]? bytes) => bytes == null ? null : UrlDecodeToBytes(bytes, 0, bytes.Length);
+        public static byte[]? UrlDecodeToBytes(byte[]? bytes) => bytes == null ? null : HttpEncoder.UrlDecode(bytes.AsSpan(0, bytes.Length));


Suggested change

public static byte[]? UrlDecodeToBytes(byte[]? bytes) => bytes == null ? null : HttpEncoder.UrlDecode(bytes.AsSpan(0, bytes.Length));

public static byte[]? UrlDecodeToBytes(byte[]? bytes) => bytes == null ? null : HttpEncoder.UrlDecode(bytes.AsSpan());

For future reference (not worth restarting CI on this PR)

…ts. (dotnet#102753)

Optimize allocations in HttpUtility.UrlDecodeToBytes

a3a068b

ghost added the area-System.Net label May 28, 2024

dotnet-policy-service bot added the community-contribution Indicates that the PR has been added by a community member label May 28, 2024

fix Span.ToArray()

d6482cc