Tasks

In addition to threads, C++ has tasks to perform work asynchronously. Tasks need the <future> header. A task is parameterised with a work package, and consists of the two associated components: a promise and a future. Both are connected via a data channel. The promise executes the work packages and puts the result in the data channel; the associated future picks up the result. Both communication endpoints can run in separate threads. It is special that the future can pick up the result at a later time; therefore, the calculation of the result by the promise is independent of the query of the result by the associated future.

Regard tasks as data channels between communication endpoints

Tasks behave like data channels between communication endpoints. One endpoint of the data channel is called the promise, the other endpoint of the data channel is called the future. These endpoints can exist in the same or different threads. The promise puts its result in the data channel...