My project has a requirement to gather data from a number of sources, then do things in response to the completion of the gathering of that data. Some of the gathering tasks have dependencies on prior gathering tasks. TPL has been a good fit because it naturally continues with tasks from their antecedents, and the "final" tasks that use the results are again dependents. Great. However, we would like to have a "sleep and regather" task that starts upon completion of the "final" tasks; this task's job is logically to be the antecedent of the "final" tasks and kick off the next cycle. In effect, the TPL's DAG becomes cyclic, or, if thought of sequentially, a loop.
Is it possible to express this cyclic requirement completely within the TPL API? If so, how? Our current implementation instead does a WaitAll() on the antecedents, and then a Task.StartNew() given a delegate that does a sleep followed by rebuilding a task graph with the WaitAll(). This works, but seems a bit artificial.
There are a few options here. What you are doing now seems reasonable.
However, you could potentially setup the entire operation as a producer/consumer scenario using BlockingCollection<T>. If your consuming enumerable used a ManualResetEvent that was set after the WaitAll completed, it could allow a single "item" to be consumed at a time, using tasks as you have it written now.
That being said, this seems like a perfect candidate for the TPL Dataflow library (in CTP).