InvalidNode is true if the node is nil, down, or drained.

IsGlobalService checks if the service is a global service.

IsReplicatedService checks if a service is a replicated service.

IsTaskDirty determines whether a task matches the given service's spec and if the given node satisfies the placement constraints.

IsTaskDirtyPlacementConstraintsOnly checks if the Placement field alone in the spec has changed.

NewTask creates a new task.

RestartCondition returns the restart condition to apply to this task.

SetServiceTasksRemove sets the desired state of tasks associated with a service to REMOVE, so that they can be properly shut down by the agent and later removed by the task reaper.

SlotTuple identifies a unique slot, in the broad sense described above.

Slot is a list of the running tasks occupying a certain slot.

TasksByTimestamp sorts tasks by applied timestamp if available, otherwise status timestamp.