Faster.Map

The goal of Faster.Map is to create a more efficient and performant alternative to the Dictionary and ConcurrentDictionary classes provided by .NET. These standard collections are widely used for key-value pair storage in .NET applications, but they have certain limitations, particularly in high-performance and concurrent scenarios.

Available Implementations:

DenseMap with SIMD Instructions: Harnesses SIMD (Single Instruction, Multiple Data) instructions for parallel processing, resulting in accelerated lookup times. Ideal for scenarios demanding high throughput and optimal CPU utilization.
RobinHoodMap with Linear Probing: Employs linear probing to resolve hash collisions, reducing the likelihood of clustering and improving access speed. Suitable for applications where a balance between performance and simplicity is required.
CMap is a high-performance, thread-safe, lockfree concurrent hashmap that uses open addressing, quadratic probing, and Fibonacci hashing to manage key-value pairs. The default load factor is set to 0.5, meaning the hash map will resize when it is half full. Note: this hashmap will only allocate once while resizing.
Installation:

You can include Faster.Map in your C# project via NuGet Package Manager:

Install-Package Faster.Map

Basic Usage

Default Hasher

By default, DenseMap uses the DefaultHasher<TKey>, which computes hashes based on the .NET GetHashCode method and uses Knuth's Multiplicative Hashing

var map = new DenseMap<int, string>();
map.Emplace(1, "Value One");
map.Emplace(2, "Value Two");

if (map.Get(1, out var value))
{
    Console.WriteLine($"Key 1 has value: {value}");
}

map.Remove(1);

Custom Hasher

By default, Faster.Map provides four built-in hashers, each optimized for different performance characteristics:

DefaultHasher GxHasher XxHash3StringHasher XxHash3Hasher

You can provide your own IHasher<TKey> implementation to customize hash computation.

Step 1: Implement a Custom Hasher

public class CustomIntHasher : IHasher<int>
{
    public ulong ComputeHash(int key)
    {
        return (ulong)(key * 2654435761); // Multiplicative hashing
    }
}

Step 2: Use the Custom Hasher in DenseMap

var customHasher = new CustomIntHasher();
var map = new DenseMap<int, string>(customHasher);

map.Emplace(1, "Value One");
map.Emplace(42, "Value Two");

if (map.Get(42, out var value))
{
    Console.WriteLine($"Key 42 has value: {value}");
}

map.Update(42, "Updated Value Two");
map.Remove(1);

Advanced Example: Hashing Strings with XxHash

Custom String Hasher

public class XxHash3StringHasher : IHasher<string>
{
    public ulong ComputeHash(string key)
    {
        return XxHash3.HashToUInt64(MemoryMarshal.AsBytes(key.AsSpan()));
    }
}

Using the String Hasher

var stringHasher = new XxHash3StringHasher();
var stringMap = new DenseMap<string, int>(stringHasher);

stringMap.Emplace("Hello", 100);
stringMap.Emplace("World", 200);

if (stringMap.Get("Hello", out var value))
{
    Console.WriteLine($"Key 'Hello' has value: {value}");
}

stringMap.Remove("World");

Tested on platforms:

x86
x64
arm
arm64

Benchmark

BenchmarkDotNet v0.13.12, Windows 11 (10.0.22631.3880/23H2/2023Update/SunValley3)
12th Gen Intel Core i5-12500H, 1 CPU, 16 logical and 12 physical cores
.NET SDK 9.0.100-preview.2.24157.14
  [Host]     : .NET 9.0.0 (9.0.24.12805), X64 RyuJIT AVX2
  DefaultJob : .NET 9.0.0 (9.0.24.12805), X64 RyuJIT AVX2

Get Benchmark

Method	Length	Mean	Error	StdDev	Median	Allocated
DenseMap	1000	0.00183 ms	0.00001 ms	0.00001 ms	0.70	341 B
RobinhoodMap	1000	0.00137 ms	0.00000 ms	0.00000 ms	0.53	175 B
Dictionary	1000	0.00260 ms	0.00001 ms	0.00001 ms	1.00	412 B
DenseMap	10000	0.02125 ms	0.00007 ms	0.00005 ms	0.30	338 B
RobinhoodMap	10000	0.01335 ms	0.00005 ms	0.00004 ms	0.19	175 B
Dictionary	10000	0.07140 ms	0.00030 ms	0.00025 ms	1.00	401 B
DenseMap	100000	0.29921 ms	0.00073 ms	0.00064 ms	0.28	341 B
RobinhoodMap	100000	0.49631 ms	0.00137 ms	0.00128 ms	0.46	175 B
Dictionary	100000	1.06807 ms	0.00240 ms	0.00224 ms	1.00	401 B
DenseMap	400000	1.78020 ms	0.03364 ms	0.03304 ms	0.36	341 B
RobinhoodMap	400000	2.28105 ms	0.01908 ms	0.01593 ms	0.47	175 B
Dictionary	400000	4.88311 ms	0.04191 ms	0.03920 ms	1.00	401 B
DenseMap	900000	5.80135 ms	0.07350 ms	0.06137 ms	0.40	341 B
RobinhoodMap	900000	8.77417 ms	0.08236 ms	0.07704 ms	0.61	175 B
Dictionary	900000	14.45441 ms	0.06885 ms	0.05376 ms	1.00	401 B
DenseMap	1000000	10.84462 ms	0.06526 ms	0.05785 ms	0.66	341 B
RobinhoodMap	1000000	10.49415 ms	0.08420 ms	0.07464 ms	0.63	175 B
Dictionary	1000000	16.54632 ms	0.11538 ms	0.09635 ms	1.00	401 B

Adding a million keys

Method	Length	Mean	Error	StdDev	Median	Allocated
DenseMap	10000	0.06526 ms	0.00130 ms	0.00286 ms	0.06490 ms	736 B
RobinhoodMap	10000	0.06092 ms	0.00212 ms	0.00602 ms	0.06100 ms	736 B
Dictionary	10000	0.23942 ms	0.00471 ms	0.00691 ms	0.23980 ms	736 B
DenseMap	100000	0.46808 ms	0.00830 ms	0.01019 ms	0.46855 ms	736 B
RobinhoodMap	100000	0.61636 ms	0.01201 ms	0.01430 ms	0.61195 ms	448 B
Dictionary	100000	2.41674 ms	0.04790 ms	0.10104 ms	2.38790 ms	736 B
DenseMap	400000	2.09803 ms	0.04190 ms	0.08746 ms	2.08300 ms	736 B
RobinhoodMap	400000	3.50303 ms	0.06982 ms	0.09079 ms	3.48000 ms	736 B
Dictionary	400000	6.47455 ms	0.33964 ms	0.95238 ms	6.73420 ms	736 B
DenseMap	800000	6.37665 ms	0.28745 ms	0.79651 ms	5.82920 ms	736 B
RobinhoodMap	800000	8.28828 ms	0.16465 ms	0.27052 ms	8.30780 ms	736 B
Dictionary	800000	16.27052 ms	0.89353 ms	2.59229 ms	16.42450 ms	736 B
DenseMap	900000	6.79059 ms	0.13023 ms	0.13934 ms	6.74320 ms	736 B
RobinhoodMap	900000	9.87488 ms	0.19034 ms	0.26054 ms	9.80475 ms	736 B
Dictionary	900000	18.87343 ms	1.00306 ms	2.95755 ms	18.42155 ms	736 B

Add and resize

Method	Length	Mean	Error	StdDev	Median	Gen0	Gen1	Gen2	Allocated
DenseMap	1000	0.08942 ms	0.00234 ms	0.00675 ms	0.08880 ms	-	-	-	37.75 KB
RobinhoodMap	1000	0.09152 ms	0.00414 ms	0.01181 ms	0.08890 ms	-	-	-	37.51 KB
Dictionary	1000	0.06777 ms	0.00519 ms	0.01522 ms	0.06260 ms	-	-	-	72.09 KB
DenseMap	10000	0.22937 ms	0.00458 ms	0.01061 ms	0.22780 ms	-	-	-	290.31 KB
RobinhoodMap	10000	0.34865 ms	0.00692 ms	0.00769 ms	0.34860 ms	-	-	-	578.18 KB
Dictionary	10000	0.39528 ms	0.01529 ms	0.04484 ms	0.37380 ms	-	-	-	657.93 KB
DenseMap	100000	1.29055 ms	0.01850 ms	0.01545 ms	1.29280 ms	-	-	-	2306.88 KB
RobinhoodMap	100000	2.34004 ms	0.03486 ms	0.05428 ms	2.32295 ms	-	-	-	4610.78 KB
Dictionary	100000	3.32307 ms	0.06625 ms	0.11776 ms	3.29280 ms	-	-	-	5896.77 KB
DenseMap	400000	5.04851 ms	0.09965 ms	0.25364 ms	5.05355 ms	-	-	-	9219.25 KB
RobinhoodMap	400000	9.31596 ms	0.18625 ms	0.30602 ms	9.23980 ms	-	-	-	18435.23 KB
Dictionary	400000	11.52668 ms	0.40434 ms	1.12042 ms	11.20910 ms	-	-	-	25374.59 KB
DenseMap	900000	12.38025 ms	0.22981 ms	0.62521 ms	12.22785 ms	-	-	-	18435.44 KB
RobinhoodMap	900000	22.62544 ms	0.69841 ms	2.01507 ms	21.66310 ms	-	-	-	36867.18 KB
Dictionary	900000	31.53625 ms	0.85001 ms	2.43885 ms	31.31300 ms	1000.0000	1000.0000	1000.0000	52626.84 KB
DenseMap	1000000	21.15451 ms	0.40257 ms	0.43075 ms	21.11780 ms	-	-	-	36867.63 KB
RobinhoodMap	1000000	26.03638 ms	0.41907 ms	0.37149 ms	26.13220 ms	-	-	-	36867.46 KB
Dictionary	1000000	34.51489 ms	0.68455 ms	0.89011 ms	34.59730 ms	1000.0000	1000.0000	1000.0000	52626.84 KB

Updating a million keys

Method	Length	Mean	Error	StdDev	Median	Allocated
RobinhoodMap	1000	0.00122 ms	0.00001 ms	0.00001 ms	0.00122 ms	-
DenseMap	1000	0.00172 ms	0.00003 ms	0.00003 ms	0.00171 ms	-
Dictionary	1000	0.00324 ms	0.00003 ms	0.00003 ms	0.00325 ms	-
DenseMap	10000	0.02178 ms	0.00013 ms	0.00012 ms	0.02181 ms	-
RobinhoodMap	10000	0.01164 ms	0.00004 ms	0.00003 ms	0.01164 ms	-
Dictionary	10000	0.08113 ms	0.00027 ms	0.00023 ms	0.08122 ms	-
DenseMap	100000	0.71209 ms	0.01294 ms	0.01211 ms	0.71421 ms	1 B
RobinhoodMap	100000	0.46221 ms	0.00153 ms	0.00143 ms	0.46254 ms	-
Dictionary	100000	1.16354 ms	0.00492 ms	0.00436 ms	1.16436 ms	1 B
DenseMap	400000	3.22005 ms	0.28612 ms	0.84362 ms	2.97777 ms	6 B
RobinhoodMap	400000	2.21473 ms	0.01258 ms	0.00982 ms	2.21459 ms	3 B
Dictionary	400000	5.35118 ms	0.03751 ms	0.03325 ms	5.34191 ms	6 B
DenseMap	900000	9.97496 ms	0.07694 ms	0.07197 ms	9.96754 ms	12 B
RobinhoodMap	900000	7.88940 ms	0.07391 ms	0.06913 ms	7.88264 ms	12 B
Dictionary	900000	15.75044 ms	0.10900 ms	0.09102 ms	15.72190 ms	23 B
DenseMap	1000000	11.15543 ms	0.11340 ms	0.10607 ms	11.14867 ms	12 B
RobinhoodMap	1000000	9.78328 ms	0.11723 ms	0.10966 ms	9.73837 ms	12 B
Dictionary	1000000	17.87004 ms	0.11745 ms	0.10412 ms	17.90677 ms	23 B

Removing a million keys

Method	Length	Mean	Error	StdDev	Median	Allocated
DenseMap	100	0.00455 ms	0.00009 ms	0.00023 ms	0.00460 ms	448 B
RobinhoodMap	100	0.00482 ms	0.00024 ms	0.00069 ms	0.00460 ms	736 B
Dictionary	100	0.00510 ms	0.00029 ms	0.00086 ms	0.00470 ms	448 B
DenseMap	10000	0.07086 ms	0.00140 ms	0.00219 ms	0.07105 ms	736 B
RobinhoodMap	10000	0.07587 ms	0.00150 ms	0.00321 ms	0.07550 ms	736 B
Dictionary	10000	0.15835 ms	0.00860 ms	0.02494 ms	0.15090 ms	736 B
DenseMap	100000	0.52464 ms	0.01039 ms	0.01197 ms	0.52030 ms	736 B
RobinhoodMap	100000	0.80547 ms	0.01996 ms	0.05824 ms	0.81955 ms	736 B
Dictionary	100000	1.20308 ms	0.02320 ms	0.03016 ms	1.19430 ms	736 B
DenseMap	400000	4.15055 ms	0.16913 ms	0.49869 ms	4.35160 ms	736 B
RobinhoodMap	400000	4.75463 ms	0.12934 ms	0.37730 ms	4.77535 ms	736 B
Dictionary	400000	5.94284 ms	0.11669 ms	0.21918 ms	5.91770 ms	736 B
DenseMap	900000	14.50084 ms	0.26427 ms	0.28276 ms	14.55160 ms	18875296 B
RobinhoodMap	900000	12.61194 ms	0.24400 ms	0.27121 ms	12.56030 ms	736 B
Dictionary	900000	17.13184 ms	0.29442 ms	0.22987 ms	17.20345 ms	736 B
DenseMap	1000000	14.90536 ms	0.29377 ms	0.53717 ms	14.76885 ms	736 B
RobinhoodMap	1000000	14.54652 ms	0.24280 ms	0.27960 ms	14.55285 ms	736 B
Dictionary	1000000	19.09788 ms	0.37338 ms	0.39952 ms	19.06965 ms	736 B

Get String Benchmark

Method	Length	Mean	Error	StdDev	Allocated
DenseMap_Default	10000	0.125 ms	0.001 ms	0.000 ms	-
DenseMap_Xxhash3	10000	0.090 ms	0.001 ms	0.001 ms	-
DenseMap_GxHash	10000	0.088 ms	0.000 ms	0.000 ms	-
RobinhoodMap	10000	0.109 ms	0.001 ms	0.001 ms	-
Dictionary	10000	0.139 ms	0.000 ms	0.000 ms	-
DenseMap_Default	100000	1.571 ms	0.011 ms	0.008 ms	1 B
DenseMap_Xxhash3	100000	1.313 ms	0.002 ms	0.002 ms	1 B
DenseMap_GxHash	100000	1.230 ms	0.004 ms	0.003 ms	1 B
RobinhoodMap	100000	1.801 ms	0.007 ms	0.006 ms	1 B
Dictionary	100000	1.830 ms	0.003 ms	0.003 ms	1 B
DenseMap_Default	400000	8.602 ms	0.168 ms	0.173 ms	12 B
DenseMap_Xxhash3	400000	6.453 ms	0.032 ms	0.025 ms	6 B
DenseMap_GxHash	400000	6.191 ms	0.043 ms	0.041 ms	6 B
RobinhoodMap	400000	17.033 ms	0.155 ms	0.138 ms	23 B
Dictionary	400000	8.841 ms	0.061 ms	0.051 ms	12 B
DenseMap_Default	800000	29.155 ms	0.132 ms	0.117 ms	23 B
DenseMap_Xxhash3	800000	21.616 ms	0.241 ms	0.214 ms	23 B
DenseMap_GxHash	800000	17.977 ms	0.086 ms	0.081 ms	23 B
RobinhoodMap	800000	42.700 ms	0.187 ms	0.156 ms	61 B
Dictionary	800000	25.280 ms	0.086 ms	0.081 ms	23 B
DenseMap_Default	900000	34.148 ms	0.348 ms	0.325 ms	49 B
DenseMap_Xxhash3	900000	25.203 ms	0.087 ms	0.073 ms	23 B
DenseMap_GxHash	900000	21.758 ms	0.105 ms	0.087 ms	23 B
RobinhoodMap	900000	51.350 ms	0.184 ms	0.172 ms	74 B
Dictionary	900000	29.715 ms	0.076 ms	0.063 ms	23 B
DenseMap_Default	1000000	42.762 ms	0.282 ms	0.264 ms	61 B
DenseMap_Xxhash3	1000000	30.722 ms	0.087 ms	0.081 ms	23 B
DenseMap_GxHash	1000000	25.237 ms	0.070 ms	0.066 ms	23 B
RobinhoodMap	1000000	61.434 ms	0.364 ms	0.322 ms	92 B
Dictionary	1000000	34.179 ms	0.650 ms	0.798 ms	49 B

Add string benchmark

Method	Length	Mean	Error	StdDev	Allocated
DenseMap	10000	0.06328 ms	0.00119 ms	0.00117 ms	-
RobinhoodMap	10000	0.11138 ms	0.00089 ms	0.00083 ms	-
Dictionary	10000	0.14030 ms	0.00101 ms	0.00084 ms	-
DenseMap	100000	0.89303 ms	0.00092 ms	0.00081 ms	1 B
RobinhoodMap	100000	1.74953 ms	0.00542 ms	0.00507 ms	1 B
Dictionary	100000	1.82837 ms	0.00251 ms	0.00222 ms	1 B
DenseMap	400000	5.69521 ms	0.08819 ms	0.07364 ms	6 B
RobinhoodMap	400000	17.48812 ms	0.11409 ms	0.10672 ms	23 B
Dictionary	400000	8.90541 ms	0.10513 ms	0.09319 ms	12 B
DenseMap	900000	25.03465 ms	0.15671 ms	0.12235 ms	23 B
RobinhoodMap	900000	52.43294 ms	0.71473 ms	0.63359 ms	74 B
Dictionary	900000	29.69477 ms	0.19468 ms	0.15200 ms	23 B
DenseMap	1000000	33.72319 ms	0.28449 ms	0.25219 ms	49 B
RobinhoodMap	1000000	62.24546 ms	0.39693 ms	0.37129 ms	92 B
Dictionary	1000000	34.00727 ms	0.10688 ms	0.08925 ms	49 B

Name		Name	Last commit message	Last commit date
Latest commit History 248 Commits
.github/workflows		.github/workflows
benchmarks		benchmarks
src		src
unittests		unittests
.gitignore		.gitignore
Faster.Map.sln		Faster.Map.sln
LICENSE		LICENSE
README.md		README.md

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Faster.Map

Available Implementations:

Basic Usage

Default Hasher

Custom Hasher

Step 1: Implement a Custom Hasher

Step 2: Use the Custom Hasher in DenseMap

Advanced Example: Hashing Strings with XxHash

Custom String Hasher

Using the String Hasher

Tested on platforms:

Benchmark

Get Benchmark

Adding a million keys

Add and resize

Updating a million keys

Removing a million keys

Get String Benchmark

Add string benchmark

About

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Contributors 3

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Wsm2110/Faster.Map

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Faster.Map

Available Implementations:

Basic Usage

Default Hasher

Custom Hasher

Step 1: Implement a Custom Hasher

Step 2: Use the Custom Hasher in DenseMap

Advanced Example: Hashing Strings with XxHash

Custom String Hasher

Using the String Hasher

Tested on platforms:

Benchmark

Get Benchmark

Adding a million keys

Add and resize

Updating a million keys

Removing a million keys

Get String Benchmark

Add string benchmark

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