Investigate perf improvements for the built-in JsonNamingPolicy (SnakeCase) for DictionaryKeyPolicy

[ahsonkhan]

One option to reduce the allocations could be to use ValueStringBuilder (see dotnet/corefx#41354 (comment)), though that doesn't help the throughput too much. It might be possible to re-implement the algorithm in ConvertName to be faster. Another idea might be to special case the first character to simplify some of the conditions within the loop (like currentIndex > 0).

BenchmarkDotNet=v0.11.5.1159-nightly, OS=Windows 10.0.18362
Intel Core i7-6700 CPU 3.40GHz (Skylake), 1 CPU, 8 logical and 4 physical cores
.NET Core SDK=3.1.100-preview1-014459
  [Host]     : .NET Core 3.0.0 (CoreCLR 4.700.19.46205, CoreFX 4.700.19.46214), X64 RyuJIT
  Job-HPZZRZ : .NET Core 3.0.0 (CoreCLR 4.700.19.46205, CoreFX 4.700.19.46214), X64 RyuJIT

PowerPlanMode=00000000-0000-0000-0000-000000000000  IterationTime=250.0000 ms  MaxIterationCount=10  
MinIterationCount=5  WarmupCount=1  

Method	Mean	Error	StdDev	Median	Min	Max	Ratio	RatioSD	Gen 0	Gen 1	Gen 2	Allocated
Default	2.426 us	0.0473 us	0.0281 us	2.425 us	2.391 us	2.473 us	1.00	0.00	0.1567	-	-	656 B
Camel	3.040 us	0.0895 us	0.0592 us	3.027 us	2.979 us	3.150 us	1.26	0.04	0.2491	-	-	1048 B
Snake	4.293 us	0.0939 us	0.0621 us	4.280 us	4.195 us	4.397 us	1.77	0.01	0.5624	-	-	2432 B

public class SerializeDictionaryWithNamingPolicy
{
    JsonSerializerOptions _camelOptions;
    JsonSerializerOptions _snakeOptions;

    Dictionary<string, string> _foo;

    [GlobalSetup]
    public void Setup()
    {
        _camelOptions = new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase, DictionaryKeyPolicy = JsonNamingPolicy.CamelCase };
        _snakeOptions = new JsonSerializerOptions { PropertyNamingPolicy = new JsonSnakeCaseNamingPolicy(), DictionaryKeyPolicy = new JsonSnakeCaseNamingPolicy() };

        _foo = new Dictionary<string, string>()
        {
            ["ID"] = "A",
            ["url"] = "A",
            ["URL"] = "A",
            ["THIS IS SPARTA"] = "A",
            ["IsCIA"] = "A",
            ["iPhone"] = "A",
            ["IPhone"] = "A",
            ["xml2json"] = "A",
            ["already_snake_case"] = "A",
            ["IsJSONProperty"] = "A",
            ["ABCDEFGHIJKLMNOP"] = "A",
            ["Hi!! This is text.Time to test."] = "A",
        };
    }

    [BenchmarkCategory(Categories.CoreFX, Categories.JSON)]
    [Benchmark(Baseline = true)]
    public string Default()
    {
        return JsonSerializer.Serialize(_foo);
    }

    [BenchmarkCategory(Categories.CoreFX, Categories.JSON)]
    [Benchmark]
    public string Camel()
    {
        return JsonSerializer.Serialize(_foo, _camelOptions);
    }

    [BenchmarkCategory(Categories.CoreFX, Categories.JSON)]
    [Benchmark]
    public string Snake()
    {
        return JsonSerializer.Serialize(_foo, _snakeOptions);
    }
}

[YohDeadfall]

Out of curiosity, could you run benchmarks only for ConvertName methods?

[ahsonkhan]

I did, previously :)

public class ConvertNamePerfComparison
{
    JsonNamingPolicy _camelPolicy;
    JsonSnakeCaseNamingPolicy _snakePolicy;

    [Params("ID", "url", "URL", "THIS IS SPARTA", "IsCIA", "iPhone", "IPhone", "xml2json", "already_snake_case", "Hi!! This is text. Time to test.", "IsJSONProperty", "ABCDEFGHIJKLMNOP")]
    public string InputString { get; set; }

    [GlobalSetup]
    public void Setup()
    {
        _camelPolicy = JsonNamingPolicy.CamelCase;
        _snakePolicy = new JsonSnakeCaseNamingPolicy();
    }

    [BenchmarkCategory(Categories.CoreFX, Categories.JSON)]
    [Benchmark (Baseline =true)]
    public string Camel()
    {
        return _camelPolicy.ConvertName(InputString);
    }

    [BenchmarkCategory(Categories.CoreFX, Categories.JSON)]
    [Benchmark]
    public string Snake()
    {
        return _snakePolicy.ConvertName(InputString);
    }
}

BenchmarkDotNet=v0.11.5.1159-nightly, OS=Windows 10.0.18362
Intel Core i7-6700 CPU 3.40GHz (Skylake), 1 CPU, 8 logical and 4 physical cores
.NET Core SDK=3.1.100-preview1-014459
  [Host]     : .NET Core 3.0.0 (CoreCLR 4.700.19.46205, CoreFX 4.700.19.46214), X64 RyuJIT
  Job-PHLPOC : .NET Core 3.0.0 (CoreCLR 4.700.19.46205, CoreFX 4.700.19.46214), X64 RyuJIT

PowerPlanMode=00000000-0000-0000-0000-000000000000  IterationTime=250.0000 ms  MaxIterationCount=10  
MinIterationCount=5  WarmupCount=1  

Method	InputString	Mean	Error	StdDev	Median	Min	Max	Ratio	RatioSD	Gen 0	Gen 1	Gen 2	Allocated
Camel	ABCDEFGHIJKLMNOP	144.050 ns	2.3565 ns	1.0463 ns	144.221 ns	142.251 ns	145.340 ns	1.00	0.00	0.0130	-	-	56 B
Snake	ABCDEFGHIJKLMNOP	286.472 ns	11.2365 ns	7.4322 ns	284.014 ns	274.514 ns	298.664 ns	1.97	0.04	0.0395	-	-	168 B
Camel	Hi!! (...)test. [32]	26.888 ns	1.0042 ns	0.6642 ns	26.523 ns	26.255 ns	27.806 ns	1.00	0.00	0.0210	-	-	88 B
Snake	Hi!! (...)test. [32]	206.047 ns	5.6577 ns	3.7422 ns	205.644 ns	200.347 ns	211.571 ns	7.67	0.25	0.0548	-	-	232 B
Camel	ID	29.211 ns	0.7578 ns	0.4509 ns	29.159 ns	28.243 ns	29.929 ns	1.00	0.00	0.0076	-	-	32 B
Snake	ID	53.312 ns	1.8611 ns	1.1075 ns	53.397 ns	51.168 ns	55.343 ns	1.83	0.04	0.0268	-	-	112 B
Camel	IPhone	25.988 ns	0.6220 ns	0.3702 ns	25.841 ns	25.507 ns	26.549 ns	1.00	0.00	0.0095	-	-	40 B
Snake	IPhone	69.932 ns	1.8686 ns	1.1120 ns	69.844 ns	68.476 ns	71.354 ns	2.69	0.07	0.0305	-	-	128 B
Camel	IsCIA	22.477 ns	0.4576 ns	0.2723 ns	22.545 ns	22.139 ns	23.023 ns	1.00	0.00	0.0076	-	-	32 B
Snake	IsCIA	87.861 ns	3.0060 ns	0.7807 ns	87.468 ns	87.330 ns	89.208 ns	3.92	0.07	0.0303	-	-	128 B
Camel	IsJSONProperty	23.641 ns	0.8762 ns	0.5795 ns	23.619 ns	22.858 ns	24.567 ns	1.00	0.00	0.0134	-	-	56 B
Snake	IsJSONProperty	182.701 ns	11.7031 ns	6.9644 ns	180.305 ns	173.343 ns	192.113 ns	7.71	0.38	0.0376	-	-	160 B
Camel	THIS IS SPARTA	48.576 ns	2.4179 ns	1.4389 ns	48.879 ns	45.882 ns	50.816 ns	1.00	0.00	0.0132	-	-	56 B
Snake	THIS IS SPARTA	270.268 ns	27.4163 ns	16.3150 ns	265.223 ns	252.873 ns	305.450 ns	5.57	0.34	0.0375	-	-	160 B
Camel	URL	37.835 ns	1.3932 ns	0.8291 ns	38.104 ns	36.627 ns	39.059 ns	1.00	0.00	0.0076	-	-	32 B
Snake	URL	84.754 ns	14.3589 ns	9.4976 ns	82.785 ns	74.739 ns	99.698 ns	2.24	0.26	0.0286	-	-	120 B
Camel	already_snake_case	2.275 ns	0.5777 ns	0.3821 ns	2.380 ns	1.801 ns	2.884 ns	1.00	0.00	-	-	-	-
Snake	already_snake_case	107.395 ns	4.0254 ns	2.3954 ns	107.700 ns	103.499 ns	110.372 ns	47.17	7.44	0.0436	-	-	184 B
Camel	iPhone	2.073 ns	0.1440 ns	0.0953 ns	2.067 ns	1.907 ns	2.219 ns	1.00	0.00	-	-	-	-
Snake	iPhone	59.832 ns	1.0612 ns	0.2756 ns	59.790 ns	59.472 ns	60.177 ns	28.28	0.72	0.0304	-	-	128 B
Camel	url	2.262 ns	0.1329 ns	0.0791 ns	2.217 ns	2.181 ns	2.382 ns	1.00	0.00	-	-	-	-
Snake	url	36.696 ns	1.3405 ns	0.8866 ns	36.580 ns	35.202 ns	38.168 ns	16.24	0.52	0.0286	-	-	120 B
Camel	xml2json	2.387 ns	0.3469 ns	0.2295 ns	2.370 ns	2.021 ns	2.730 ns	1.00	0.00	-	-	-	-
Snake	xml2json	61.309 ns	3.3973 ns	2.2471 ns	60.858 ns	58.979 ns	66.335 ns	25.96	3.35	0.0323	-	-	136 B

[YohDeadfall]

Thanks, will take a look at it, but only starting next week.

[YohDeadfall]

@ahsonkhan Probably it could be made faster by eliminating nullable types which I introduced to clarify the logic.

[iSazonov]

I wonder - dotnet/corefx#41354 is not merged (Although a lot of effort has been spent there
!) but the issue is a open :-)

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[ghost]

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