planner: move getTaskPlanCost to planner core util (#53218)

ref #51664, ref #52714

pkg/planner/core/core_init.go

@@ -27,6 +27,7 @@ import (
 func init() {
 	// For code refactor init.
 	utilfuncp.HasMaxOneRowUtil = HasMaxOneRow
+	utilfuncp.GetTaskPlanCost = getTaskPlanCost
 	utilfuncp.AppendCandidate4PhysicalOptimizeOp = appendCandidate4PhysicalOptimizeOp
 
 	// For mv index init.

pkg/planner/core/find_best_task.go

@@ -344,11 +344,11 @@ func (p *LogicalSequence) iterateChildPlan(
 
 // compareTaskCost compares cost of curTask and bestTask and returns whether curTask's cost is smaller than bestTask's.
 func compareTaskCost(curTask, bestTask base.Task, op *optimizetrace.PhysicalOptimizeOp) (curIsBetter bool, err error) {
-	curCost, curInvalid, err := getTaskPlanCost(curTask, op)
+	curCost, curInvalid, err := utilfuncp.GetTaskPlanCost(curTask, op)
 	if err != nil {
 		return false, err
 	}
-	bestCost, bestInvalid, err := getTaskPlanCost(bestTask, op)
+	bestCost, bestInvalid, err := utilfuncp.GetTaskPlanCost(bestTask, op)
 	if err != nil {
 		return false, err
 	}

pkg/planner/util/utilfuncp/func_pointer_misc.go

@@ -37,3 +37,10 @@ var HasMaxOneRowUtil func(p base.LogicalPlan, childMaxOneRow []bool) bool
 // todo: (2) arenatlx, remove this func pointer when concrete Logical Operators moved out of core.
 var AppendCandidate4PhysicalOptimizeOp func(pop *optimizetrace.PhysicalOptimizeOp, lp base.LogicalPlan,
 	pp base.PhysicalPlan, prop *property.PhysicalProperty)
+
+// GetTaskPlanCost returns the cost of this task.
+// The new cost interface will be used if EnableNewCostInterface is true.
+// The second returned value indicates whether this task is valid.
+// todo: (3) arenatlx, remove this func pointer when Task pkg is moved out of core, and
+// getTaskPlanCost can be some member function usage of its family.
+var GetTaskPlanCost func(t base.Task, pop *optimizetrace.PhysicalOptimizeOp) (float64, bool, error)