task Derivation

Class task is an abstract base class. You must override method task::execute. Method execute should perform the necessary actions for running the task, and then return the next task to execute, or NULL if the scheduler should choose the next task to execute. Typically, if non-NULL, the returned task is one of the predecessor tasks of this. Unless one of the recycle/reschedule methods, described in Section Recycling Tasks, is called while method execute() is running, the this object will be implicitly destroyed after method execute returns.

Override the virtual destructor if necessary to release resources allocated by the constructor.

Override note_affinity to improve cache reuse across tasks, as described in Section Affinity.

Processing of execute()

When the scheduler decides that a thread should begin executing a task, it performs the following steps:

  1. Invokes execute() and waits for it to return.
  2. If the task has not been marked by a method recycle_*:
    1. Calls the task's destructor.
    2. If the task's parent is not null, then atomically decrements successor->refcount, and if becomes zero, puts the successor into the ready pool.
    3. Frees the memory of the task for reuse.
  3. If the task has been marked for recycling:
    1. If marked by recycle_to_reexecute(deprecated), puts the task back into the ready pool.
    2. Otherwise it was marked by recycle_as_child or recycle_as_continuation.
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