Philiprehberger.AsyncLock

Async-aware synchronization primitives — AsyncLock, AsyncSemaphore, and AsyncOnce for safe mutual exclusion.

Installation

dotnet add package Philiprehberger.AsyncLock

Usage

AsyncLock

using Philiprehberger.AsyncLock;

var asyncLock = new AsyncLock();

using (await asyncLock.LockAsync())
{
    // Critical section — only one caller at a time
    await DoWorkAsync();
}

AsyncSemaphore

var semaphore = new AsyncSemaphore(maxCount: 3);

using (await semaphore.WaitAsync())
{
    // Up to 3 concurrent callers allowed
    await DoWorkAsync();
}

AsyncOnce

var once = new AsyncOnce<HttpClient>(async () =>
{
    var client = new HttpClient();
    // expensive initialization
    return client;
});

var client = await once.GetAsync(); // Factory runs once, result is cached

API

AsyncLock

Method	Description
LockAsync(CancellationToken cancellationToken = default)	Acquires the lock asynchronously. Returns an IDisposable that releases the lock when disposed.

AsyncSemaphore

Method	Description
AsyncSemaphore(int maxCount)	Creates a semaphore with the specified maximum count.
WaitAsync(CancellationToken cancellationToken = default)	Waits to enter the semaphore. Returns an IDisposable that releases the semaphore when disposed.
CurrentCount	Gets the number of remaining entries.

AsyncOnce<T>

Method	Description
AsyncOnce(Func<Task<T>> factory)	Creates an instance with the specified async factory.
GetAsync(CancellationToken cancellationToken = default)	Returns the cached value, executing the factory on first call.
IsCompleted	Whether the factory has been executed.

Releaser

Method	Description
Releaser	Readonly struct implementing IDisposable that releases a SemaphoreSlim on disposal.

Development

dotnet build src/Philiprehberger.AsyncLock.csproj --configuration Release

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License

MIT