An externally initializing singleton that uses double-check asynchronous locking, with optional async and sync disposal
Get Started
$ dotnet add package Soenneker.Utils.AsyncSingletonReadme
Soenneker.Utils.AsyncSingleton
An externally initializing singleton that uses double-check asynchronous locking, with optional async and sync disposal
Installation
dotnet add package Soenneker.Utils.AsyncSingleton
Example
The example below is a long-living HttpClient implementation using AsyncSingleton. It avoids the additional overhead of IHttpClientFactory, and doesn't rely on short-lived clients.
public class HttpRequester : IDisposable, IAsyncDisposable
{
private readonly AsyncSingleton<HttpClient> _client;
public HttpRequester()
{
// This func will lazily execute once it's retrieved the first time.
// Other threads calling this at the same moment will asynchronously wait,
// and then utilize the HttpClient that was created from the first caller.
_client = new AsyncSingleton<HttpClient>(() =>
{
var socketsHandler = new SocketsHttpHandler
{
PooledConnectionLifetime = TimeSpan.FromMinutes(10),
MaxConnectionsPerServer = 10
};
return new HttpClient(socketsHandler);
});
}
public async ValueTask Get()
{
// retrieve the singleton async, thus not blocking the calling thread
await (await _client.Get()).GetAsync("https://google.com");
}
// Disposal is not necessary for AsyncSingleton unless the type used is IDisposable/IAsyncDisposable
public ValueTask DisposeAsync()
{
GC.SuppressFinalize(this);
return _client.DisposeAsync();
}
public void Dispose()
{
GC.SuppressFinalize(this);
_client.Dispose();
}
}