Intro

My notes on C#'s asynchronous programming constructs

Documentation

Asynchronous operations begin the work and return a Task that represents the ongoing work.
You can only use await in an async method, and Main cannot be async.
A method which uses await must have the async attribute

public async Task MyAsyncMethod()
{
   await SomeAsyncTask;
   MoreWorkToBeDone;
}

Using the async attribute on a method does not make it run on a separate thread.
Once the method reaches the await, it examins if the task (eg SomeAsyncTask) has already completed.
- If it has completed , then it continues to the next statement (MoreWorkToBeDone), just alike a synchronous statement.
- If it hasn’t completed, then
  - It instructs the task (eg SomeAsyncTask) that it needs to execute the code that follows when it completes its own execution.
  - The method returns immediately (ie, it doesn’t execute MoreWorkToBeDone).
  - Later, when the task (eg SomeAsyncTask) completes, it can execute the rest of the async method.
- Async methods can return: Task<T>, Task, or void.
  - In almost all cases, you want to return Task<T> or Task. Avoid returning void.
    - eg public async Task<List<string>> MyAsyncMethod returns a task that when completed will return a list of strings.