asyncsemaphore's Introduction

AsyncSemaphore

A simple wrapper around a SemaphoreSlim featuring:

Automatic releasing without try/finally blocks by utilising the IDisposable using pattern
Guarantee that release can only be called once per WaitAsync call
Analyzers to help you implement the desired pattern
An IAsyncSemaphore interface for if you need to mock

Install

dotnet add package AsyncSemaphore

Usage

private readonly AsyncSemaphore _asyncSemaphore = new AsyncSemaphore(1);

public async Task MyMethod()
{
    // Just assign the `IDisposable` returned from `WaitAsync` to a variable and use the using statement with it
    using var lockHandle = await _asyncSemaphore.WaitAsync();

    // Do whatever you want - Even if we throw exceptions, we'll release the semaphore once we leave this method's scope
    await DoSomethingInsideLock();
}

or scoped:

private readonly AsyncSemaphore _asyncSemaphore = new AsyncSemaphore(1);

public async Task MyMethod()
{
    // or create your own scope with {} braces - And after you leave that scope, your lock will be released
    using (await _asyncSemaphore.WaitAsync())
    {
        await DoSomethingInsideLock();
    }

    await DoSomethingAfterLockReleased();
}

Benchmarks and allocations can be seen below.

BenchmarkDotNet v0.13.12, Windows 11 (10.0.22621.3593/22H2/2022Update/SunValley2)
11th Gen Intel Core i7-1185G7 3.00GHz, 1 CPU, 8 logical and 4 physical cores
.NET SDK 8.0.106
  [Host]     : .NET 8.0.6 (8.0.624.26715), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  DefaultJob : .NET 8.0.6 (8.0.624.26715), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Mean	Error	StdDev	Allocated
Raw_Semaphore_Slim	38.89 ns	0.622 ns	0.519 ns	-
AsyncSemaphore_With_Inherited_Scope	51.36 ns	0.466 ns	0.413 ns	-
AsyncSemaphore_With_Braced_Scope	51.04 ns	0.274 ns	0.243 ns	-

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