How Can I Guarantee a Single Invocation of an Asynchronous Method?

Single Invocation of Asynchronous Methods: A Robust Approach

In asynchronous programming, preventing multiple invocations of a method is crucial, particularly during initialization. Duplicate or concurrent execution can lead to data inconsistencies and application errors. While SemaphoreSlim offers a solution, a more streamlined approach uses AsyncLazy<T>.

AsyncLazy<T> provides a lazily-evaluated, asynchronously computed value. By initializing an AsyncLazy<bool> with your asynchronous operation, you guarantee single execution.

Here's a refined AsyncLazy<T> implementation optimized for this purpose:

<code class="language-csharp">public class AsyncLazy<T> : Lazy<Task<T>>
{
    public AsyncLazy(Func<T> valueFactory) :
        base(() => Task.Run(valueFactory)) { }

    public AsyncLazy(Func<Task<T>> taskFactory) :
        base(() => Task.Run(() => taskFactory())) { }

    public TaskAwaiter<T> GetAwaiter() { return Value.GetAwaiter(); }
}</code>

Usage is straightforward:

<code class="language-csharp">private AsyncLazy<bool> asyncLazy = new AsyncLazy<bool>(async () =>
{
    await DoStuffOnlyOnceAsync();
    return true;
});</code>

Note: The bool return type is a placeholder; DoStuffOnlyOnceAsync's return value isn't utilized here.

This AsyncLazy<T> implementation offers a clean and efficient way to ensure a single asynchronous method invocation, maintaining application data integrity during initialization.

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