Tasking Namespace

Function Documentation

template <typename Handler> Tasking::GroupItem Tasking::onGroupDone(Handler &&handler, Tasking::CallDoneIf callDoneIf = CallDoneIf::SuccessOrError)

Constructs a group's element holding the group done handler. By default, the handler is invoked whenever the group finishes. Pass a non-default value for the callDoneIf argument when you want the handler to be called only on a successful or failed execution. Depending on the group's workflow policy, this handler may also be called when the running group is canceled (e.g. when stopOnError element was used).

The passed handler is of the std::function<DoneResult(DoneWith)> type. Optionally, each of the return DoneResult type or the argument DoneWith type may be omitted (that is, its return type may be void). For more information on a possible handler type, refer to GroupItem::GroupDoneHandler.

When the handler is invoked, all of the group's child tasks are already finished.

If a group contains the Storage elements, the handler is invoked before the storages are destructed, so that the handler may still perform a last read of the active storages' data.

See also GroupItem::GroupDoneHandler and onGroupSetup().

template <typename Handler> Tasking::GroupItem Tasking::onGroupSetup(Handler &&handler)

Constructs a group's element holding the group setup handler. The handler is invoked whenever the group starts.

The passed handler is either of the std::function<SetupResult()> or the std::function<void()> type. For more information on a possible handler type, refer to GroupItem::GroupSetupHandler.

When the handler is invoked, none of the group's child tasks are running yet.

If a group contains the Storage elements, the handler is invoked after the storages are constructed, so that the handler may already perform some initial modifications to the active storages.

See also GroupItem::GroupSetupHandler and onGroupDone().

Tasking::GroupItem Tasking::parallelLimit(int limit)

Constructs a group's element describing the execution mode.

The execution mode element in a Group specifies how the direct child tasks of the Group are started.

For convenience, when appropriate, the sequential or parallel global elements may be used instead.

The limit defines the maximum number of direct child tasks running in parallel:

• When limit equals to 0, there is no limit, and all direct child tasks are started together, in the oder in which they appear in a group. This means the fully parallel execution, and the parallel element may be used instead.
• When limit equals to 1, it means that only one child task may run at the time. This means the sequential execution, and the sequential element may be used instead. In this case, child tasks run in chain, so the next child task starts after the previous child task has finished.
• When other positive number is passed as limit, the group's child tasks run in parallel, but with a limited number of tasks running simultanously. The limit defines the maximum number of tasks running in parallel in a group. When the group is started, the first batch of tasks is started (the number of tasks in a batch equals to the passed limit, at most), while the others are kept waiting. When any running task finishes, the group starts the next remaining one, so that the limit of simultaneously running tasks inside a group isn't exceeded. This repeats on every child task's finish until all child tasks are started. This enables you to limit the maximum number of tasks that run simultaneously, for example if running too many processes might block the machine for a long time.

In all execution modes, a group starts tasks in the oder in which they appear.

If a child of a group is also a group, the child group runs its tasks according to its own execution mode.

See also sequential and parallel.

Tasking::GroupItem Tasking::workflowPolicy(Tasking::WorkflowPolicy policy)

Constructs a group's workflow policy element for a given policy.

For convenience, global elements may be used instead.

See also stopOnError, continueOnError, stopOnSuccess, continueOnSuccess, stopOnSuccessOrError, finishAllAndSuccess, finishAllAndError, and WorkflowPolicy.