1. You Can Add a Continuation To A Completed Task
And the continuation will be run. Given the code:
Neither assert will fire. Thus the continue block has executed despite
being added to Task
t1 had run.
This does of course prevent a race between
returning a task that is scheduled (and therefore possibly already completed)
with a call to
2. You Can Continue A Task Multiple Times
And the continuations run concurrently. I’m not sure that this would be useful very often (only if multiple tasks need to be started following a single initial task), but nice to know there is not an arbitrary zero or one multiplicity on continuations. Sample code:
Depending on the system this can give different results, but one should see the two “before sleep” messages before either of the two “after sleep” messages: both tasks are executing concurrently.
TaskFactory.FromAsync Starts the Task
No illustration of this, it just doesn’t say so in the documentation.
I discovered this when a
InvalidOperationException was thrown for
starting an already complete task (only two statements later, the intermediate
one adding a continuation). To be fair to the designers, there is really no
reason to want to delay the execution of the task as the creation is a single
statement (and if you really needed to, just use a helper (anonymous) function).