Jaahas.StringCache

A .NET string cache that can be used as an alternative to calling string.Intern. The concept for this library is taken from Sergey Teplyakov's blog post here.

The library offers both custom string caching using ConcurrentDictionary<TKey, TValue> and a wrapper around native string interning, allowing you to choose the approach that best fits your requirements.

Usage

// Cache strings using the shared instance
var cached1 = Jaahas.StringCache.Shared.Intern("Hello, World!");
var cached2 = Jaahas.StringCache.Shared.Intern("Hello, World!");

// Both variables reference the same string instance
Console.WriteLine(ReferenceEquals(cached1, cached2)); // True

// Check cache size
Console.WriteLine($"Cache contains {Jaahas.StringCache.Shared.Count} strings");

// Clear the cache when needed
Jaahas.StringCache.Shared.Clear();

Benchmarks

Benchmarks can be found in the Jaahas.StringCache.Benchmarks project. The benchmarks compare the performance of the Jaahas.StringCache class against the built-in string.Intern method.

Example results from running the benchmarks on an Apple M4 Pro with .NET 9.0.7:

BenchmarkDotNet v0.15.2, macOS Sequoia 15.6 (24G84) [Darwin 24.6.0]
Apple M4 Pro, 1 CPU, 14 logical and 14 physical cores
.NET SDK 9.0.303
  [Host]     : .NET 9.0.7 (9.0.725.31616), Arm64 RyuJIT AdvSIMD [AttachedDebugger]
  DefaultJob : .NET 9.0.7 (9.0.725.31616), Arm64 RyuJIT AdvSIMD


| Method          | Count   | Mean          | Error        | StdDev       | Ratio | RatioSD | Gen0   | Allocated | Alloc Ratio |
|---------------- |-------- |--------------:|-------------:|-------------:|------:|--------:|-------:|----------:|------------:|
| NativeInterning | 10000   |   1,137.35 us |    22.721 us |    21.253 us |  1.00 |    0.03 |      - |   6.34 KB |        1.00 |
| CacheInterning  | 10000   |      35.51 us |     0.701 us |     1.005 us |  0.03 |    0.00 | 0.5493 |   4.57 KB |        0.72 |
|                 |         |               |              |              |       |         |        |           |             |
| NativeInterning | 100000  |   9,536.63 us |   104.627 us |    97.868 us |  1.00 |    0.01 |      - |   6.32 KB |        1.00 |
| CacheInterning  | 100000  |     195.14 us |     0.955 us |     0.893 us |  0.02 |    0.00 | 0.4883 |   4.62 KB |        0.73 |
|                 |         |               |              |              |       |         |        |           |             |
| NativeInterning | 1000000 | 146,965.17 us | 1,643.612 us | 1,537.436 us |  1.00 |    0.01 |      - |   5.09 KB |        1.00 |
| CacheInterning  | 1000000 |   4,066.65 us |    33.637 us |    31.464 us |  0.03 |    0.00 |      - |   4.93 KB |        0.97 |

Building the Solution

The repository uses Cake for cross-platform build automation. The build script allows for metadata such as a build counter to be specified when called by a continuous integration system such as TeamCity.

A build can be run from the command line using the build.ps1 PowerShell script or the build.sh Bash script. For documentation about the available build script parameters, see build.cake.

Software Bill of Materials

To generate a Software Bill of Materials (SBOM) for the repository in CycloneDX XML format, run build.ps1 or build.sh with the --target BillOfMaterials parameter.

The resulting SBOM is written to the artifacts/bom folder.