kbsletten/multiwait

A library that makes awaiting multiple tasks easy.

MultiWait

MultiWait addresses the ergonomic problem of handling multiple async requests simultaneously while still getting the best possible concurrency. Without MultiWait, you have to create temporary variables for all the in-flight tasks like this:

var userTask = GetUserByUserIdAsync(userId);
var userReposTask = GetUserReposByUserIdAsync(userId);
var userIssuesTask = GetUserIssuesByUserIdAsync(userId);
var userPRsTask = GetUserPullRequestsByUserIdAsync(userId);

var user = await userTask;
var userRepos = await userReposTask;
var userIssues = await userIssuesTask;
var userPRs = await userPRsTask;

But with MultiWait it can become this:

var (user, userRepos, userIssues, userPrs) = await
	Tasks.WhenAll(
		GetUserByUserIdAsync(userId),
		GetUserReposByUserIdAsync(userId),
		GetUserIssuesByUserIdAsync(userId),
		GetUserPullRequestsByUserIdAsync(userId)
	);

Installation

MultiWait requires .NET Standard 2.0 which allows it to run on the following runtimes:

• .NET Framework 4.6.1 or greater
• .NET Core 2.0 or greater

This package can be added to a project with NuGet by running:

• Install-Package MultiWait -Source nuget.org in Visual Studio NuGet Console
• dotnet add package MultiWait on your command line in a .NET Core project

Usage

Tasks.WhenAll

This method is the workhorse of this library, allowing you to await up to 16 concurrent tasks all of different types. This differs from System.Threading.Tasks.Task.WhenAll<T>(T...) in two key ways: This method can take arguments of different types (unlike T[]) and it cannot take a different number of arguments at runtime (or even more than 16 at compile-time). The main utility of this method is to allow you to await 2 or more tasks simultaneously without creating temporary variables or spreading await through your whole method.

var (x, y) = await Tasks.WhenAll(GetXAsync(), GetYAsync());

Tasks.WhenAny

This method is this library's analog to System.Threading.Tasks.WhenAny. It allows you to wait for the first of a couple of tasks, getting the result of the first and returning the default value for the others.

var (value, cache) = await Tasks.WhenAny(GetValueAsync(), GetCacheAsync());
if (value != null) return value;
return MapToValue(cache);

Tasks.WaitAll

This method is just like Tasks.WhenAll except that it waits the tasks, it doesn't await them.

var (x, y) = Task.WaitAll(GetXAsync(), GetYAsync());

Tasks.WaitAny

This method is just like Tasks.WhenAny except that it waits the tasks, it doesn't await them.

var (value, cache) = Tasks.WaitAny(GetValueAsync(), GetCacheAsync());
if (value != null) return value;
return MapToValue(cache);