Downhole tool actuators and indexing mechanisms

A downhole tool control apparatus comprising:

• an outer sub, the outer sub being tubular, the outer sub having an inner surface defining a control apparatus bore;
• a control assembly having an inner profile that includes first and second control sleeve diameters, the control assembly being longitudinally moveable relative to the outer sub;
• a control pin positioned within the control apparatus bore and mechanically coupled to the outer sub and having a pin outer profile, wherein the pin outer profile includes first and second pin diameters;
• a stroking assembly, the stroking assembly positioned within the control apparatus bore, the stroking assembly including:
• a spline barrel having a spline projection, the spline barrel being rotatable and axially moveable relative to the outer sub;
• and
• a spline pocket positioned to engage the spline projection of the stroking assembly;
• wherein a flow path is defined between the control pin and the control assembly, the flow path having a total flow area, and wherein the total flow area is can be changed by moving the control assembly relative to the control pin.